The JI
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
 QUICK SEARCH:   [advanced]


     
 


This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow Request Permissions
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Ha, S. J.
Right arrow Articles by Sung, Y. C.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Ha, S. J.
Right arrow Articles by Sung, Y. C.
The Journal of Immunology, 1999, 163: 2902-2908.
Copyright © 1999 by The American Association of Immunologists

A Novel Function of IL-12p40 as a Chemotactic Molecule for Macrophages1

Sang Jun Ha2,*, Chu Hee Lee2,*, Seong Beom Lee*, Chang Min Kim{dagger}, Kyung Lib Jang{ddagger}, Hee Sup Shin* and Young Chul Sung3,*

* Department of Life Science, Center for Biofunctional Molecules, Pohang University of Science and Technology, Kyungbuk, Korea; {dagger} Laboratory of Molecular Oncology, Korea Cancer Center Hospital, Seoul, Korea; and {ddagger} Department of Microbiology, College of Natural Science, Pusan National University, Pusan, Korea


    Abstract
 Top
 Abstract
 Introduction
 Materials and Methods
 Results
 Discussion
 References
 
IL-12p70 plays a pivotal role in regulating the Th1/Th2 balance in the initial stage of immune responses. In contrast, IL-12p40, which is produced excess over IL-12p70, has been known to down-regulate IL-12p70-mediated responses by acting as an antagonist. To investigate in vivo function of IL-12p40, RH7777 rat hepatoma cells were engineered to inducibly express mouse IL-12p40 under the tight control of doxycycline (dox). In the absence of dox, s.c. injection of these cells into syngeneic rat was shown to generate tumors. However, the induction of IL-12p40 by dox was sufficient for inhibiting tumor formation, as well as for tumor regression. Immunohistochemical analysis showed that macrophages, but not CD4+ T, CD8+ T, and NK cells, were predominantly recruited into tumor sites as early as 3 days after IL-12p40 induction. These results were further supported by the observation that IL-12p40, but not C-terminal deletion mutants by more than 5 amino acids, was able to chemoattract peritoneal macrophages in vitro, suggesting that IL-12p40, when produced in a large excess over IL-12p70 in vivo, can initially amplify the immune responses against tumors by directly recruiting macrophages. Our findings indicate that IL-12p40 may function as an effector molecule as well as an antagonist of IL-12p70.


    Introduction
 Top
 Abstract
 Introduction
 Materials and Methods
 Results
 Discussion
 References
 
Interleukin-12 is a proinflammatory cytokine that is produced by APC, such as macrophages, dendritic cells, and B cells (1, 2, 3, 4). The biologically functional form of IL-12 is a 70-kDa heterodimer (IL-12p70), which consists of disulfide-bonded 40-kDa (p40) and 35-kDa (p35) subunits (5), and plays a key role in the induction of cellular immunity by promoting the proliferation of NK and T cells and the differentiation to Th1 cells, and by stimulating CTL- and NK-mediated cytolytic activity in response to a variety of pathogens (6, 7, 8, 9, 10). IL-12p40 is expressed and secreted as monomer and homodimer in a large excess over IL-12p70 in vitro (11, 12, 13, 14) and in vivo (13, 15). It has been demonstrated that IL-12p40 blocks the activities of IL-12p70 by competitively binding to the IL-12 receptor in vitro, which led to the hypothesis that IL-12p40 serves as a natural antagonist of IL-12p70 (12, 16, 17). Consistent with this hypothesis, IL-12p40 reduces IL-12p70-mediated Th1 responses in vivo (18, 19, 20). However, it has been reported that IL-12p40 enhances alloantigen-specific Th1 development (21), which suggests that IL-12p40 may function similarly to the biologically active IL-12p70 under certain conditions.

The physiological function of IL-12p40 in vivo is still unclear, and, therefore, further investigations are needed to define its role in the immune system. In addition, the fact that mouse IL-12p40 can be produced in a 5- to 90-fold excess over IL-12p70 both in vivo and in vitro has led us to speculate the existence of additional immunological roles of IL-12p40 in a point of the efficiency of the immune system. To investigate the potential roles of IL-12p40 in vivo, we demonstrated that the expression of IL-12p40 induces macrophage recruitment in a tumor model system and serves as a chemoattractant for peritoneal macrophages in vitro.


    Materials and Methods
 Top
 Abstract
 Introduction
 Materials and Methods
 Results
 Discussion
 References
 
Animals

Eight- to ten-week-old female Buffalo (BUF/N) rats and BALB/c mice were purchased from Harlan Sprague-Dawley (Indianapolis, IN). These animals were maintained in a positive pressure facility (one-way flow) and were fed autoclaved food and water.

Cell lines and Abs

RH7777, rat hepatoma cells of BUF/N rat, and COS-7 cells were purchased from the American Type Culture Collection (ATCC; Manassas, VA). These cells were maintained in DMEM that was supplemented with 10% heat-inactivated FBS, 3.7 g/L sodium bicarbonate, and 2.5 g/L HEPES. Mouse anti-rat CD4 (CD134), mouse anti-rat CD8 (CD8b), mouse anti-rat NK (NKR-P1A), and mouse anti-rat macrophage (macrophage subset) mAbs were purchased from PharMingen (San Diego, CA). These reagents specifically react with activated CD4+ T lymphocytes, peripheral T cytotoxic/suppressor cells, NK cells/small subset of T lymphocytes, and macrophages, respectively. Rabbit anti-IL-12Rß1 and rabbit anti-cyclin E polyclonal Abs were purchased from Santa Cruz Biotechnology (Santa Cruz, CA).

Expression plasmids

Mouse IL-12p40 cDNA was inserted into the inducible mammalian expression vector, pUHD10-3, to construct pUHD10-3/p40. The pUHD10-3 plasmid, kindly provided by Dr. H. Bujard (University of California, Berkeley, CA) carries the regulatory region with human CMV minimal promoter and heptamerized upstream tet-operator, as described (22). The IL-12p40 expression plasmid, pCIN/p40-1/313 (wt) was constructed by inserting cDNA of mouse IL-12p40 gene into pCI-neo plasmid (Promega, Madison, WI). Deleted forms of the mouse IL-12p40 gene were created by PCR amplification of the desired nucleotides. To construct expression vectors of IL-12p40 deletion mutants, pCIN/p40-1/263, 1/273, 1/283, 1/293, 1/303, 1/308, 1/310 (the numbers indicate the amino acid residue of the IL-12p40 protein contained in the mutant products), common sense primer, including ATG translation start codon and different antisense primers (for pCIN/p40-1/263: 5'-AAAGGATCCTACTCTGTCTCC-3', 1/273: 5'-AAAGGATCCTAGAGGAACGCA-3', 1/283: 5'-AAAGGATCCTAGCATTGGACT-3',1/293:5'-AAAGGATCCTACTGAGCTTGC-3', 1/303: 5'-AAAGGATCCTACTTGCTGCAT-3', 1/308: 5'-AAAGGATCCTAGGGAACACAT-3',1/310:5'-AAAGGATCCTACCTGCAGGGA-3'), were used to amplify each deleted form of IL-12p40 gene. Amplified genes were directly inserted into the pGEM T Easy vector (Promega), and then each of them was subcloned into the XhoI and EcoRI site of pCI-neo. The resulting plasmids, including pCIN/p40-1/313 (wt) and pCI-neo as a negative control, were transfected into COS-7 cells by calcium phosphate method and cultured in CHO-SFMII medium for 48 h. The quantity of IL-12p40 and mutant IL-12p40 was measured in the supernatants of transfected cells using ELISA kit (Genzyme, Cambridge, MA).

Preparation of engineered RH7777 cells

To prepare a tumor cell line that inducibly expresses IL-12p40, pUHD10-3/p40 was cotransfected with a pUHD172-1 neo at a 4:1 ratio into RH7777 cells using calcium phosphate method. The plasmid, pUHO172-1 neo, provided by Dr. H. Bujard, encodes a neomycin phosphotransferase and carries the regulatory region with human CMV promoter/enhancer and the rtTA-gene (22). RH7777/neo cell, as a negative control, was also prepared by cotransfection with pUHD10-3 and pUHD172-1 neo. These cells were cultured in the media containing G418 (350 µg/ml) (Sigma, St. Louis, MO), and resistant clones were selected. The resistant clones were plated at a density of 105 cells per well in a 6-well plate and were incubated with various concentrations of doxycycline (dox)4 (0–104 ng/ml; Sigma) for 48 h. The supernatants of the transfected clones were quantified for mouse IL-12p40 expression using an ELISA kit.

Tumor challenge

BUF/N rats were s.c. injected into a leg with 5 x 106 engineered RH7777 cells (RH7777/p40 or RH7777/neo) in 0.4 ml of serum-free media. The local tumor growth was determined by measuring the diameter of tumors with calipers every 2 days. Rats were administered with or without dox (200 µg/ml) in drinking water that contained 5% sucrose, as previously described (23, 24). Specific protocols are presented in the legends of individual experiments.

Histological and immunohistochemical analyses

Tumors were removed from rats and fixed in 4% buffered formalin, dehydrated, cleared, and embedded in paraffin wax using standard histological procedures. The paraffin blocks of tissue were sectioned serially at 7 µm, affixed to gelatin-coated slides, and stored at room temperature. The prepared serial sections were stained with hematoxylin and eosin for histological studies. For immunohistochemical analyses, slides were deparaffinized by xylene and rehydrated through a decreasing series of ethanol solutions (100%, 90%, 70%, water). Endogenous peroxidase activity and nonspecific binding were blocked by 3% H2O2 treatment for 10 min and PBS that contained 5% normal horse serum for 60 min. The slides were then incubated for 24 h in a humid chamber with 1:10 diluted mouse mAbs (CD8b, CD134, NKR-P1A, and macrophage subset), respectively. The slides were then washed with PBS and incubated for 2 h with an anti-mouse biotinylated Ab diluted 1:200 in 5% normal horse serum. After washing with PBS, the slides were incubated for 1 h with streptavidin and biotinylated HRP (Novostain super ABC kit; Novocastra, Claremont, Newcastle, U.K.), and washed in PBS. The color reaction was performed in diaminobenzidine solution (Vector stain ABC kit; Vector Laboratories, Burlingame, CA).

Macrophage cultures and chemotaxis assay

Resting peritoneal macrophages (PM) were harvested as previously described (25) by washing the peritoneal cavity of BUF/N rats and BALB/c mice with RPMI 1640 medium containing 10% heat-inactivated FBS and were seeded in a tissue culture dish. After incubation for 9 h at 37°C in a humidified CO2 incubator, nonadherent cells were removed by washing three times with medium, and the remaining adherent cells were used in the following experiment. Chemotaxis was assayed with a modification of the 96-well microchemotaxis assay, as previously described (26). For the assay, recombinant mouse (rm)IL-12p40 homodimer (R&D Systems, Minneapolis, MN), rmIL-12p70 heterodimer (R&D Systems), rmIL-2 (PharMingen), and BSA (Sigma) were diluted in PBS with 0.2% BSA to several concentrations. Wild-type IL-12p40 and its deletion mutants were obtained from supernatants of COS-7 cell transfected with pCIN/p40–1/313 (wt), 1/263, 1/273, 1/283, 1/293, 1/303, 1/308, and 1/310, and diluted to a final concentration of 100 ng/ml with CHO-SFMII medium containing 0.2% BSA. The culture supernatant from pCI-neo transfectant, a negative control, was used without dilution. Specimens were placed in the lower wells of a 24-well culture plate and overlaid on a chamber with an 8-µm pore size polycarbonate membrane (Nalge Nunc International, Roskilde, Denmark). In all chemotaxis assays used in this study, the PM suspension (106 cells/ml) that was diluted in HBSS medium with 0.2% BSA was added to the top wells of the chamber. After incubation for 2 h at 37°C, the cells on the upper surface of the membrane were wiped off, and the cells on the lower surface of the membrane were fixed in 4% buffered formalin and stained with hematoxylin. Chemotactic activity was represented as the number of cells that migrated across the membrane.


    Results
 Top
 Abstract
 Introduction
 Materials and Methods
 Results
 Discussion
 References
 
Production of engineered RH7777 cells, RH7777/p40 and RH7777/neo

To examine the in vivo role of IL-12p40, a rat hepatoma cell line (RH7777) was transfected with a vector that expresses mouse IL-12p40 under inducible conditions and modified RH7777 clone (RH7777/p40), which could express IL-12p40 only after dox treatment was selected. As a negative control, RH7777/neo was also established by transfection of a control vector that does not contain the IL-12p40 gene. The expression of IL-12p40 in RH7777/p40 was efficiently induced and gradually increased in proportion to the dox concentration (Fig. 1Go). In contrast, RH7777/neo did not express IL-12p40 in the presence or absence of dox. Irrespective of dox treatment, the morphology and the growth kinetics between RH7777/p40 and RH7777/neo were indistinguishable from those of parental RH7777 cells in vitro, which indicated that neither expression of IL-12p40 nor dox treatment had any cytotoxic effects on cell growth.



View larger version (17K):
[in this window]
[in a new window]
 
FIGURE 1. The level of IL-12p40 that was expressed from engineered RH7777 cells by dox treatment. RH7777/neo ({square}) cells and RH7777/p40 ({blacksquare}) were plated at a density of 105 cells per 60 mm dish and treated with dox at the indicated concentration for 48 h. The amount of IL-12p40 in each cell supernatant was measured by ELISA. The results are the mean ± SD of four independent experiments.

 
Effect of IL-12p40 expression on tumor formation and regression

Without dox treatment, the injection of RH7777/p40 and RH7777/neo cells into syngeneic BUF/N rats resulted in no difference of tumor formation between two groups of animals. However, when dox was supplied soon after tumor cell injection, only 2 of 18 rats of the RH7777/p40-injected group developed tumors, whereas all RH7777/neo-injected rats, as a control, developed tumors (Fig. 2GoA). In addition, we could observe that there were inflammatory immune responses, such as redness and swelling, at the injection sites of the RH7777/p40 group, but not at those of the RH7777/neo group, between 5 and 15 days postinjection of tumor cells in the presence of dox. It was surprising that IL-12p40 itself appeared to have an antitumor effect, considering the fact that IL-12p40 has been thought to be an antagonist of IL-12. To further investigate the activity of IL-12p40, tumors ~0.5 cm in diameter were established in the absence of dox after injection of RH7777/p40 or RH7777/neo. When dox was supplied to the RH7777/p40 group, the growth of established tumors was retarded for 8–12 days after dox treatment (Fig. 2GoB). The tumors then regressed and eventually disappeared. In addition, the redness and swelling was observed at the tumor sites of the rats for ~10 days after dox treatment, suggesting that IL-12p40 expression may induce an inflammatory reaction in tumor sites. As expected, the tumors of the RH7777/neo group still continued to grow after dox treatment. When the tumor-regressed rats were challenged with parental RH7777 cells at 1 mo after tumor regression, ~75% of them were also protected from tumor development, whereas all naive rats formed tumors (Fig. 2GoC). These results suggest that a memory immune response against the parental tumor cells is also generated in the tumor-regressed rats.



View larger version (19K):
[in this window]
[in a new window]
 
FIGURE 2. IL-12p40-induced protective immunity against hepatoma cells. A, The effect of IL-12p40 induction in rats that were injected with engineered RH7777 cells. After s.c. injection of 5x106 RH7777/neo ({square}) or RH7777/p40 ({blacksquare}) cells into BUF/N rats, drinking water with (right) or without (left) 200 µg/ml dox was supplied to these animals for 30 days, and the number of tumor-bearing subjects was counted at 36 days postinjection. B, The kinetics of tumor regression after the induction of IL-12p40. Dox (200 µg/ml) was given to rats with tumors that were ~0.5 cm in diameter by injection of either RH7777/neo ({square}) or RH7777/p40 ({blacksquare}) cells. Tumor growth was monitored every 2 days for 20 days. C, The protection of cured rats against challenge with parental tumor cells. Tumor-regressed rats ({blacksquare}) were challenged with parental RH7777 cells at 1 mo after tumor regression. As a negative control, naive rats ({square}) of the same age were used. The number of rats with tumor was counted at day 20 after challenge. The marks above bars indicate no. of rats with tumors/no. of rats injected.

 
Rapid recruitment of macrophages into tumor sites in IL-12p40-mediated tumor regression

To identify the immune cells involved in IL-12p40-mediated tumor regression, both histological and immunohistochemical analyses were conducted at 1, 3, 7, and 14 days after the initiation of dox treatment on rats bearing tumors that were up to 0.5 cm in diameter. Histological analyses revealed that in RH7777/p40-injected rats, a few inflammatory cells were located in the margin of the tumor injection site at day 1, and that tumor-infiltrating cells began to appear around tumor mass at day 3 (Fig. 3GoA, a and b). At day 14, necrosis as well as numerous infiltrating inflammatory cells were observed at the tumor site (Fig. 3GoAc). In contrast, the RH7777/neo group exhibited the typical features of active hepatoma and few infiltrating inflammatory cells, even at day 14 (Fig. 3GoAd). To examine the kinetic profile of infiltrating inflammatory cells that are associated with tumor regression, immunohistochemical analyses were performed using mouse mAbs to CD8+ T, CD4+ T, NK cell, and macrophage-specific surface markers. At day 3, mouse macrophages, but not other immune cells, were recruited into the margin of the tumors (Fig. 3GoB, a, e, i, and m). At day 7, macrophages were the predominant cell type infiltrated into the tumors, although low levels of additional cell types, such as CD8+, CD4+ T cells, and NK cells, were observed (Fig. 3GoB, b, f, j, and n). These results, together with the growth retardation of the established tumors of RH7777/p40 group up to 8–12 days after dox treatment, suggest that infiltrating macrophages are predominantly involved in the initial stages of tumor regression. At day 14, CD8+, CD4+ T cells, and NK cells, as well as macrophages, had infiltrated into the necrotic tumor sites (Fig. 3GoB, c, g, k, and o). It is likely that these cells are associated with the tumor regression that was observed 12–18 days after dox treatment. In RH7777/neo group, inflammatory cells, such as T, NK cells, and macrophages, were not observed at any time point up to day 14 (Fig. 3GoB, d, h, l, and p).



View larger version (135K):
[in this window]
[in a new window]
 
FIGURE 3. Histological and immunohistochemical analyses of the regressing tumors after IL-12p40 induction with dox. Tumors that were ~0.5 cm in diameter were generated by injection of 5 x 106 RH7777/p40 or RH7777/neo cells and excised at different time points after dox treatment (200 µg/ml). A, Tumor sections were stained with hematoxylin and eosin for histopathological analyses of RH7777/p40 group (a--c) and RH7777/neo group (d). B, Paraffin-blocked tissue sections were stained with mouse mAbs against rat CD8 (CD8b) (a–d), CD4 (CD134) (e–h) (B), NK (NKR-P1A) (i–l), and macrophage (macrophage subset) (m–p) for immunohistochemical analyses. Day(s) 3, 7, and 14 indicate the time point of tumor excision after dox treatment following injection of RH7777/p40 (a–c, e–g, i–k, and m–o) or RH7777/neo (d, h, l, and p) cells. Original magnification, x100.

 
Macrophage chemotactic activity of IL-12p40

To examine whether the macrophage recruitment into tumors is directly caused by IL-12p40, an in vitro chemotaxis assay for PM from BUF/N rat, as described in Materials and Methods, was performed using a rmIL-12p40 homodimer. BSA and rmIL-2, which has been known as a macrophage activator, were used as controls in these experiments. As the concentration of rmIL-12p40 in the lower chemotaxis chamber was increased from 1 ng/ml to 1000 ng/ml, PM began to migrate across the polycarbonate membrane in a concentration-dependent manner (Fig. 4GoA). However, neither rmIL-2 nor BSA had measurable chemotactic activity for PM. The heat treatment of rmIL-12p40 dramatically decreased its chemotactic activity for rat PM, indicating that the activity of IL-12p40 is dependent on its conformation (Fig. 4GoB). The similar chemotactic effect of IL-12p40, at a concentration of 1–1000 ng/ml, was also observed with primary PM from BALB/c mouse and RAW264.7 cells, mouse macrophage cell line (data not shown). To exclude the possibility that the chemotactic function of IL-12p40 is an indirect effect mediated by other cytokines or chemokines released from IL-12p40-treated macrophages, we examined the chemotactic activity of IL-12p40 in the presence of Ab against IL-12Rß1 subunit (anti-IL-12R). This Ab, but not anti-cyclin E, was able to reduce the IFN-{gamma} production from mouse PM treated with 150 pg/ml of IL-12p70 at the concentration of 20 µg/ml (data not shown). The anti-cyclin E is an isotype-matched Ab obtained from the same species. Anti-IL-12R, but not anti-cyclin E, appeared to inhibit the chemotactic activity of IL-12p40 (Fig. 4GoC). As controls, the PM chemotaxis by both fMLP, known as a strong chemoattractant, and BSA was not affected in the presence or absence of anti-IL-12R and anti-cyclin E. These data indicate that macrophage chemotactic activity is a direct effect of IL-12p40.



View larger version (29K):
[in this window]
[in a new window]
 
FIGURE 4. The chemotactic effect of IL-12p40 on PM. The dose response of rmIL-12p40 ({diamondsuit}), rmIL-2 ({triangleup}), or BSA ({circ}) in rat (BUF/N) PM chemoattraction was assessed (A). The chemotactic activity of each protein boiled for 15 min for rat PM was compared with the intact form at a concentration of 100 ng/ml (B). Mouse PM were incubated with 20 µg/ml of anti-IL-12Rß1 ({blacksquare}) or anti-cyclin E () for 20 min at 37°C, and the PM suspension was used for the examination of chemotactic activity by 1 µg/ml of rmIL-12p40. A total of 5 nM fMLP and 0.2% BSA were used as positive and negative reference chemoattractants, respectively (C). To examine the effect of IL-12p40 on PM chemoattraction by IL-12p70, mouse PM chemoattraction by rmIL-12p40 at the indicated concentrations was assessed in either presence ({blacksquare}) or absence ({square}) of rmIL-12p70 (1 ng/ml). The PM migration in response to rmIL-12p70 alone was presented as dotted lines (D). The results were expressed as the average number of cells that migrated into the 8-mm2 lower surface of the filter in at least three independent experiments.

 
Recently, we reported that IL-12p70 has a direct chemotactic activity for macrophages at low concentrations (28). Since IL-12p40 has been known to be a potent IL-12p70 antagonist by inhibiting proliferation of phorbol ester-activated splenocytes and synthesis of IFN-{gamma} from splenocytes treated with IL-12p70 (12), it was of interest to characterize whether IL-12p40 also has an agonistic or antagonistic activity on IL-12p70-mediated PM chemoattraction. In the presence of 1 ng/ml of rmIL-12p70, the effect of rmIL-12p40 at various concentrations was observed in terms of macrophage chemoattraction (Fig. 4GoD). The rmIL-12p40 at relatively low concentrations (0.1–10 ng/ml) does not appear to inhibit the chemotactic activity of IL-12p70. Interestingly, at higher concentrations of rmIL-12p40 (10–1000 ng/ml), the similar chemotactic pattern was shown, regardless of the presence or absence of rmIL-12p70. As expected, when mouse PM were cotreated with 150 pg/ml of rmIL-12p70 and various concentrations of rmIL-12p40 (0–600 ng/ml), the increase in the concentration of rmIL-12p40 gradually decreased the IFN-{gamma} secretion from rmIL-12p70-treated PM (data not shown), which is consistent with a previous result observed in splenocytes (12). Taken together, our data indicated that IL-12p40 appears to, by itself, have a PM chemotactic activity, but acts as an antagonist in the IFN-{gamma} release from IL-12p70-treated PM.

C-terminal portion of IL-12p40 is responsible for PM chemotaxis and IL-12 receptor binding

To further confirm the macrophage chemotactic activity of IL-12p40, seven different C-terminal deleted forms of the IL-12p40 gene were generated. The C-terminal deletion mutants of IL-12p40 (amino acid 1–310, 1–308, 1–303, 1–293, 1–283, 1–273, and 1–263) were obtained by transient transfection of these deleted forms into COS-7 cells, quantified by using IL-12p40 ELISA kit, and used for chemotaxis assay. The p40-1/310, 3 amino acids-deleted mutant, still retained the chemotactic activity similar to that of p40-1/313, wild type of IL-12p40. In contrast, deletion of more than only 5 amino acids from C-terminal of IL-12p40 significantly reduced chemotactic activity for mouse PM (Fig. 5GoA). A similar result was also observed when primary rat PM were used (data not shown). As shown in Fig. 4GoC, PM chemotaxis by IL-12p40 appeared to be mediated by the binding to its receptor. Therefore, it was necessary to determine whether C-terminal portion of IL-12p40 affected the receptor binding. Because IL-12p40 was known to reduce the IL-12p70-induced IFN-{gamma} production by competitive binding to the IL-12 receptor, we examined whether C-terminal deletion mutants of IL-12p40 inhibit the IFN-{gamma} production from mouse PM in the presence of IL-12p70. Only p40-1/310 mutant appeared to reduce the IFN-{gamma} production as much as wild-type IL-12p40, while the other mutants did not inhibit the IFN-{gamma} production by IL-12p70 (Fig. 5GoB). Taken together, these results suggest that C-terminal portion of IL-12p40 is associated with its receptor binding and consequently plays a role in mediating the PM chemotaxis.



View larger version (25K):
[in this window]
[in a new window]
 
FIGURE 5. The role of IL-12p40 C-terminal portion on chemotaxis and receptor binding. COS7 cells were transfected with pCI-neo, pCIN/p40–1/313 (wt), and IL-12p40 mutant expression vectors (pCIN/p40-1/310, 1/308, 1/303, 1/293, 1/283, 1/273, and 1/263). Wild-type IL-12p40 and its mutants obtained from culture supernatants were diluted to 100 ng/ml and used for chemotaxis assay on mouse PM. The results were expressed as the average number of cells that migrated into the 8-mm2 lower surface of the filter in one representative from at least three independent experiments (A). Mouse PM were plated with 2 x 105 cells into 96-well and treated for 1 h with 100 ng/ml of wild type IL-12p40 or its C-terminal deletion mutants used in A. Then, rmIL-12p70 was added to each well at the final concentration of 150 pg/ml. After 48 h, the culture supernatants were harvested and used for IFN-{gamma} ELISA assay (B). The results are the mean ± SD of three independent experiments.

 

    Discussion
 Top
 Abstract
 Introduction
 Materials and Methods
 Results
 Discussion
 References
 
In this paper, we demonstrated that IL-12p40 has macrophage-attracting activity in vivo and in vitro as a novel function, in addition to an antagonistic activity against IL-12p70. These observations indicate that macrophage is another type of cell responsive to IL-12p40, as well as the source of IL-12 production. Furthermore, our data suggest that in the infection of foreign pathogens, IL-12p40 may play a positive regulatory role by recruiting macrophages as well as a negative regulatory role, such as the inhibition of overactivated Th1 immune responses by IL-12p70. Therefore, it is speculated that IL-12p40 may be able to generate a rapid but modulatory IL-12-mediated immune response.

It has been demonstrated that IL-12p40 is produced as monomer and homodimer in large excess over IL-12p70 (11, 12, 13, 14, 15). The mouse IL-12p40 has been reported to inhibit IL-12-mediated responses by competitive binding to IL-12 receptor with an affinity similar to that of IL-12p70 (12, 16). Also, there is an in vivo role of IL-12p40 as a IL-12p70 antagonist, in which IL-12p40 delayed the allograft rejection of cardiac myoblast (18), and IL-12p40 transgenic mice showed the increased susceptibility to the malaria infection (20). However, it was recently reported that IL-12p40 may have additional in vivo roles that are not related to the biological antagonist of IL-12p70 (21, 27). Piccotti et al. (21) showed that IL-12p40 homodimer exacerbated, rather than delayed, cardiac allograft rejection , which partially agreed with our results. These unexpected results were explained in the sequential report that CD4+ T cells are likely to provide requisite help for the environment for signaling by IL-12p40 and then, CD8+ T cells differentiated by CD4+ T cells are developed by the IL-12p40 (27). In our immunohistochemical analyses, CD4+ and CD8+ T cells were not detected in the tumors generated by the injection of IL-12p40-expressing tumor cells until these tumors began to regress, indicating that IL-12p40 does not respond to CD4+ and CD8+ T cells but chemoattracts macrophages to induce inflammation in the initial stage. Therefore, it is suggested that IL-12p40 may be initially involved in enhancing nonclassical immune responses, leading to the induction of tumor regression.

Recently, we reported that IL-12p70 has chemotactic activity for macrophages in vitro (28). This activity was maximum at the concentration of 0.1 ng/ml IL-12p70 and gradually decreased at higher concentrations. In contrast, it is of interest to note that IL-12p40 showed the enhanced chemotactic activity as the concentration of IL-12p40 was increased to 1000 ng/ml, which is maximum concentration used in this assay condition, indicating that the chemotactic activity of IL-12p40 for macrophages is concentration-dependent. In the infection of foreign pathogens, the amount of IL-12p40 was known to be produced up to 90 times more than that of IL-12p70 (13, 14, 15). Although IL-12p40 was shown to have an antagonistic effect of IL-12p70-mediated biological activity (12), it is unlikely that the presence of IL-12p40 inhibits the chemotactic activity of IL-12p70. It may be impossible to directly demonstrate the potential antagonistic activity of IL-12p40, since both of them appear to have similar chemotactic activity. In summary, it is suggested that IL-12p40 appears to be an antagonist of IL-12p70 in terms of IFN-{gamma} induction, but acts as a macrophage chemoattractant together with IL-12p70 to induce the initial immune responses.

There are several reports that nonlymphoid immune cells migrated by cytokine or chemokine augmented tumor immunogenicity (29, 30, 31, 32, 33), which is similar to the observation of our study. TCA3, one of ß chemokines, was shown to recruit neutrophils and macrophages into tumors accompanied by tumor necrosis, suggesting that the chemotactic activity of TCA3 appeared to induce the tumor regression in the end (29). Based on these reports, it can be speculated that chemotactic activity of IL-12p40 may be closely associated with IL-12p40-mediated tumor regression.

Taken together, it would be carefully reevaluated that IL-12p40 may be a therapeutically useful antiinflammatory agent in the therapy of autoimmune disease and the induction of tolerance in transplantation procedures, since IL-12p40 has a potential to initiate inflammatory immune response via macrophage chemoattraction.


    Acknowledgments
 
We thank Dr. Hermann Bujard for the plasmids, pUHD10-3, and pUHD172-1 neo. We also thank Sang Chun Lee for devoted animal care.


    Footnotes
 
1 This work was supported by Korea Cancer Center Hospital Grants NI97209 and NI9808901 and by the Genetic Engineering Program, the Ministry of Education Grants N96102 and N97072. Back

2 S.J.H. and C.H.L. contributed equally to this work. Back

3 Address correspondence and reprint requests to Dr. Young Chul Sung, Department of Life Science, Pohang University of Science and Technology, San 31, Hyoja-Dong, Pohang, Kyungbuk, 790-784, Korea. E-mail address: Back

4 Abbreviations used in this paper: dox, doxycycline; PM, peritoneal macrophages; rm, recombinant mouse. Back

Received for publication August 21, 1998. Accepted for publication June 25, 1999.


    References
 Top
 Abstract
 Introduction
 Materials and Methods
 Results
 Discussion
 References
 

  1. Kobayashi, M., L. Fitz, M. Ryan, R. M. Hewick, S. C. Clark, S. Chan, R. Loudon, F. Sherman, B. Perussia, G. Trinchieri. 1989. Identification and purification of natural killer cell stimulatory factor (NKSF), a cytokine with multiple biologic effects on human lymphocytes. J. Exp. Med. 170:827.[Abstract/Free Full Text]
  2. Stern, A. S., F. J. Podlaski, J. D. Hulmes, Y. C. Pan, P. M. Quinn, A. G. Wolitzky, P. C. Familletti, D. L. Stremlo, T. Truitt, R. Chizzonite, M. K. Gately. 1990. Purification to homogeneity and partial characterization of cytotoxic lymphocyte maturation factor from human B-lymphoblastoid cells. Proc. Natl. Acad. Sci. USA 87:6808.[Abstract/Free Full Text]
  3. D’Andrea, A., M. Rengaraju, N. M. Valiante, J. Chehimi, M. Kubin, M. Aste, S. H. Chan, M. Kobayashi, D. Young, E. Nickbarg, et al 1992. Production of natural killer cell stimulatory factor (interleukin 12) by peripheral blood mononuclear cells. J. Exp. Med. 176:1387.[Abstract/Free Full Text]
  4. Macatonia, S. E., N. A. Hosken, M. Litton, P. Vieira, C. S. Hsieh, J. A. Culpepper, M. Wysocka, G. Trinchieri, K. M. Murphy, A. O’Garra. 1995. Dendritic cells produce IL-12 and direct the development of Th1 cells from naïve CD4+ T cells. J. Immunol. 154:5071.[Abstract]
  5. Gubler, U., A. O. Chua, D. S. Schoenhaut, C. M. Dwyer, W. McComas, R. Motyka, N. Nabavi, A. G. Wolitzky, P. M. Quinn, P. C. Familletti, M. K. Gately. 1991. Coexpression of two distinct genes is required to generate secreted bioactive cytotoxic lymphocyte maturation factor. Proc. Natl. Acad. Sci. USA 88:4143.[Abstract/Free Full Text]
  6. Gately, M. K., B. B. Desai, A. G. Wolitzky, P. M. Quinn, C. M. Dwyer, F. J. Podlaski, P. C. Familletti, F. Sinigaglia, R. Chizonnite, U. Gubler, A. S. Stern. 1991. Regulation of human lymphocyte proliferation by a heterodimeric cytokine, IL-12 (cytotoxic lymphocyte maturation factor). J. Immunol. 147:874.[Abstract]
  7. Chan, S. H., B. Perussia, J. W. Gupta, M. Kobayashi, M. Pospisil, H. A. Young, S. F. Wolf, D. Young, S. C. Clark, G. Trinchieri. 1991. Induction of interferon {gamma} production by natural killer cell stimulatory factor: characterization of the responder cells and synergy with other inducers. J. Exp. Med. 173:869.[Abstract/Free Full Text]
  8. Hsieh, C. S., S. E. Macatonia, C. S. Tripp, S. F. Wolf, A. O’Garra, K. M. Murphy. 1993. Development of TH1 CD4+ T cells through IL-12 produced by Listeria-induced macrophages. Science 260:547.[Abstract/Free Full Text]
  9. Manetti, R., P. Parronchi, M. G. Giudizi, M. P. Piccinni, E. Maggi, G. Trinchieri, S. Romagnani. 1993. Natural killer cell stimulatory factor (interleukin 12 [IL-12]) induces T helper type 1 (Th1)-specific immune responses and inhibits the development of IL-4-producing Th cells. J. Exp. Med. 177:1199.[Abstract/Free Full Text]
  10. Gately, M. K., R. R. Warrier, S. Honasoge, D. M. Carvajal, D. A. Faherty, S. E. Connaughton, T. D. Anderson, U. Sarmiento, B. R. Hubbard, M. Murphy. 1994. Administration of recombinant IL-12 to normal mice enhances cytolytic lymphocyte activity and induces production of IFN-{gamma} in vivo. Int. Immunol. 6:157.[Abstract/Free Full Text]
  11. Podlaski, F. J., V. B. Nanduri, J. D. Hulmes, Y. C. Pan, W. Levin, W. Danho, R. Chizzonite, M. K. Gately, A. S. Stern. 1992. Molecular characterization of interleukin 12. Arch. Biochem. Biophys. 294:230.[Medline]
  12. Gillessen, S., D. Carvajal, P. Ling, F. J. Podlaski, D. L. Stremlo, P. C. Familletti, U. Gubler, D. H. Presky, A. S. Stern, M. K. Gately. 1995. Mouse interleukin-12 (IL-12) p40 homodimer: a potent IL-12 antagonist. Eur. J. Immunol. 25:200.[Medline]
  13. Heinzel, F. P., R. M. Rerko, P. Ling, J. Hakimi, D. S. Schoenhaut. 1994. Interleukin 12 is produced in vivo during endotoxemia and stimulates synthesis of {gamma} interferon. Infect. Immun. 62:4244.[Abstract/Free Full Text]
  14. Zhang, M., M. K. Gately, E. Wang, J. Gong, S. F. Wolf, S. Lu, R. L. Modlin, P. F. Barnes. 1994. Interleukin 12 at the site of disease in tuberculosis. J. Clin. Invest. 93:1733.
  15. Wysocka, M., M. Kubin, L. Q. Vieira, L. Ozmen, G. Garotta, P. Scott, G. Trinchieri. 1995. Interleukin-12 is required for interferon-{gamma} production and lethality in lipopolysaccharide-induced shock in mice. Eur. J. Immunol. 25:672.[Medline]
  16. Mattner, F., S. Fischer, S. Guckes, S. Jin, H. Kaulen, E. Schmitt, E. Rude, T. Germann. 1993. The interleukin-12 subunit p40 specifically inhibits effects of the interleukin-12 heterodimer. Eur. J. Immunol. 23:2202.[Medline]
  17. Ling, P., M. K. Gately, U. Gubler, A. S. Stern, P. Lin, K. Hollfelder, C. Su, Y. C. Pan, J. Hakimi. 1995. Human IL-12 p40 homodimer binds to the IL-12 receptor but does not mediate biologic activity. J. Immunol. 154:116.[Abstract]
  18. Kato, K., O. Shimozato, K. Hoshi, H. Wakimoto, H. Hamada, H. Yagita, K. Okumura. 1996. Local production of the p40 subunit of interleukin 12 suppresses T-helper 1-mediated immune responses and prevents allogeneic myoblast rejection. Proc. Natl. Acad. Sci. USA 93:9085.[Abstract/Free Full Text]
  19. Abdi, K., S. H. Herrmann. 1997. CTL generation in the presence of IL-4 is inhibited by free p40. J. Immunol. 159:3148.[Abstract]
  20. Yoshimoto, T., C. Wang, T. Yoneto, S. Waki, S. Sunaga, Y. Komagata, M. Mitsuyama, J. Miyazaki, H. Nariuchi. 1998. Reduced T helper 1 responses in IL-12 p40 transgenic mice. J. Immunol. 160:588.[Abstract/Free Full Text]
  21. Piccotti, J. R., S. Y. Chan, R. E. Goodman, J. Magram, E. J. Eichwald, D. K. Bishop. 1996. IL-12 antagonism induces T helper 2 responses, yet exacerbates cardiac allograft rejection. J. Immunol. 157:1951.[Abstract]
  22. Gossen, M., H. Bujard. 1995. Transcriptional activation by tetracyclines in mammalian cells. Science 268:1766.[Abstract/Free Full Text]
  23. Kistner, A., M. Gossen, F. Zimmermann, J. Jerecic, C. Ullmer, H. Lubbert, H. Bujard. 1996. Doxycycline-mediated quantitative and tissue-specific control of gene expression in transgenic mice. Proc. Natl. Acad. Sci. USA 93:10933.[Abstract/Free Full Text]
  24. Bohl, D., N. Naffakh, J. M. Heard. 1997. Long-term control of erythropoietin secretion by doxycycline in mice transplanted with engineered primary myoblasts. Nat. Med. 3:299.[Medline]
  25. Puddu, P., L. Fantuzzi, P. Borghi, B. Varano, G. Rainaldi, E. Guillemard, W. Malorni, P. Nicaise, S. F. Wolf, F. Belardelli, S. Gessani. 1997. IL-12 induces IFN-{gamma} expression and secretion in mouse peritoneal macrophages. J. Immunol. 159:3490.[Abstract]
  26. Bacon, K., R. D. Camp, F. M. Cunningham, P. M. Woollard. 1988. Contrasting in vitro lymphocyte chemotactic activity of the hydroxyl enantiomers of 12-hydroxy-5,8,10,14-eicosatetraenoic acid. Br. J. Pharmacol. 95:966.[Medline]
  27. Piccotti, J. R., S. Y. Chan, K. Li, E. J. Eichwald, D. K. Bishop. 1997. Differential effects of IL-12 receptor blockade with IL-12 p40 homodimer on the induction of CD4+ and CD8+ IFN-{gamma}-producing cells. J. Immunol. 158:643.[Abstract]
  28. Ha, S. J., S. B. Lee, C. M. Kim, H. S. Shin, Y. C. Sung. 1998. Rapid recruitment of macrophages in IL-12-mediated tumor regression. Immunology 95:156.[Medline]
  29. Laning, J., H. Kawasaki, E. Tanaka, Y. Luo, M. E. Dorf. 1994. Inhibition of in vivo tumor growth by the ß chemokine, TCA3. J. Immunol. 153:4625.[Abstract]
  30. Tepper, R. I., P. K. Pattengale, P. Leder. 1989. Murine interleukin-4 displays potent anti-tumor activity in vivo. Cell 57:503.[Medline]
  31. Tepper, R. I., R. L. Coffman, P. Leder. 1992. An eosinophil-dependent mechanism for the antitumor effect of interleukin-4. Science 257:548.[Abstract/Free Full Text]
  32. Bottazzi, B., S. Walter, D. Govoni, F. Colotta, A. Mantovani. 1992. Monocyte chemotactic cytokine gene transfer modulates macrophage infiltration, growth, and susceptibility to IL-2 therapy of a murine melanoma. J. Immunol. 148:1280.[Abstract]
  33. Tannenbaum, C. S., R. Tubbs, D. Armstrong, J. H. Finke, R. M. Bukowski, T. A. Hamilton. 1998. The CXC chemokines IP-10 and Mig are necessary for IL-12-mediated regression of the mouse RENCA tumor. J. Immunol. 161:927.[Abstract/Free Full Text]



This article has been cited by other articles:


Home page
J. Virol.Home page
R. Feuer, C. M. Ruller, N. An, J. M. Tabor-Godwin, R. E. Rhoades, S. Maciejewski, R. R. Pagarigan, C. T. Cornell, S. J. Crocker, W. B. Kiosses, et al.
Viral Persistence and Chronic Immunopathology in the Adult Central Nervous System following Coxsackievirus Infection during the Neonatal Period
J. Virol., September 15, 2009; 83(18): 9356 - 9369.
[Abstract] [Full Text] [PDF]


Home page
J. Immunol.Home page
D.-J. Kim, J.-I. Youn, S.-H. Seo, H.-T. Jin, and Y.-C. Sung
Differential Regulation of Antigen-Specific CD8+ T Cell Responses by IL-12p40 in a Dose-Dependent Manner
J. Immunol., June 1, 2008; 180(11): 7167 - 7174.
[Abstract] [Full Text] [PDF]


Home page
Am. J. Respir. Crit. Care Med.Home page
C. L. Mikols, L. Yan, J. Y. Norris, T. D. Russell, A. P. Khalifah, R. R. Hachem, M. M. Chakinala, R. D. Yusen, M. Castro, E. Kuo, et al.
IL-12 p80 Is an Innate Epithelial Cell Effector That Mediates Chronic Allograft Dysfunction
Am. J. Respir. Crit. Care Med., August 15, 2006; 174(4): 461 - 470.
[Abstract] [Full Text] [PDF]


Home page
Mol. Pharmacol.Home page
I. Alloza, A. Baxter, Q. Chen, R. Matthiesen, and K. Vandenbroeck
Celecoxib Inhibits Interleukin-12 {alpha}beta and beta2 Folding and Secretion by a Novel COX2-Independent Mechanism Involving Chaperones of the Endoplasmic Reticulum
Mol. Pharmacol., May 1, 2006; 69(5): 1579 - 1587.
[Abstract] [Full Text] [PDF]


Home page
Cancer Res.Home page
M. Torroella-Kouri, X. Ma, G. Perry, M. Ivanova, P. J. Cejas, J. L. Owen, V. Iragavarapu-Charyulu, and D. M. Lopez
Diminished Expression of Transcription Factors Nuclear Factor {kappa}B and CCAAT/Enhancer Binding Protein Underlies a Novel Tumor Evasion Mechanism Affecting Macrophages of Mammary Tumor-Bearing Mice
Cancer Res., November 15, 2005; 65(22): 10578 - 10584.
[Abstract] [Full Text] [PDF]


Home page
J. Immunol.Home page
S. Klebe, D. J. Coster, P. J. Sykes, S. Swinburne, P. Hallsworth, J.-P. Y. Scheerlinck, R. Krishnan, and K. A. Williams
Prolongation of Sheep Corneal Allograft Survival by Transfer of the Gene Encoding Ovine IL-12-p40 but Not IL-4 to Donor Corneal Endothelium
J. Immunol., August 15, 2005; 175(4): 2219 - 2226.
[Abstract] [Full Text] [PDF]


Home page
J. Biol. Chem.Home page
H. Xu, H. Kurihara, T. Ito, H. Kikuchi, K. Yoshida, H. Yamanokuchi, and A. Asari
The Keratan Sulfate Disaccharide Gal(6S03) {beta}1,4-GlcNAc(6S03) Modulates Interleukin 12 Production by Macrophages in Murine Thy-1 Type Autoimmune Disease
J. Biol. Chem., May 27, 2005; 280(21): 20879 - 20886.
[Abstract] [Full Text] [PDF]


Home page
GutHome page
A Stallmach, T Marth, B Weiss, B M Wittig, A Hombach, C Schmidt, M Neurath, M Zeitz, S Zeuzem, and H Abken
An interleukin 12 p40-IgG2b fusion protein abrogates T cell mediated inflammation: anti-inflammatory activity in Crohn's disease and experimental colitis in vivo
Gut, March 1, 2004; 53(3): 339 - 345.
[Abstract] [Full Text] [PDF]


Home page
J. Immunol.Home page
T. D. Russell, Q. Yan, G. Fan, A. P. Khalifah, D. K. Bishop, S. L. Brody, and M. J. Walter
IL-12 p40 Homodimer-Dependent Macrophage Chemotaxis and Respiratory Viral Inflammation Are Mediated through IL-12 Receptor {beta}1
J. Immunol., December 15, 2003; 171(12): 6866 - 6874.
[Abstract] [Full Text] [PDF]


Home page
JEMHome page
G. Rotta, E. W. Edwards, S. Sangaletti, C. Bennett, S. Ronzoni, M. P. Colombo, R. M. Steinman, G. J. Randolph, and M. Rescigno
Lipopolysaccharide or Whole Bacteria Block the Conversion of Inflammatory Monocytes into Dendritic Cells In Vivo
J. Exp. Med., October 20, 2003; 198(8): 1253 - 1263.
[Abstract] [Full Text] [PDF]


Home page
J. Immunol.Home page
F. Huaux, M. Arras, D. Tomasi, V. Barbarin, M. Delos, J.-P. Coutelier, A. Vink, S. H. Phan, J.-C. Renauld, and D. Lison
A Profibrotic Function of IL-12p40 in Experimental Pulmonary Fibrosis
J. Immunol., September 1, 2002; 169(5): 2653 - 2661.
[Abstract] [Full Text] [PDF]


Home page
LupusHome page
B R Lauwerys, J Van Snick, and F A Houssiau
Serum IL-12 in systemic lupus erythematosus: absence of p70 heterodimers but presence of p40 monomers correlating with disease activity
Lupus, June 1, 2002; 11(6): 384 - 387.
[Abstract] [PDF]


Home page
J. Immunol.Home page
C. Parham, M. Chirica, J. Timans, E. Vaisberg, M. Travis, J. Cheung, S. Pflanz, R. Zhang, K. P. Singh, F. Vega, et al.
A Receptor for the Heterodimeric Cytokine IL-23 Is Composed of IL-12R{beta}1 and a Novel Cytokine Receptor Subunit, IL-23R
J. Immunol., June 1, 2002; 168(11): 5699 - 5708.
[Abstract] [Full Text] [PDF]


Home page
J. Immunol.Home page
C. Holscher, R. A. Atkinson, B. Arendse, N. Brown, E. Myburgh, G. Alber, and F. Brombacher
A Protective and Agonistic Function of IL-12p40 in Mycobacterial Infection
J. Immunol., December 15, 2001; 167(12): 6957 - 6966.
[Abstract] [Full Text] [PDF]


Home page
J. Immunol.Home page
J. Lehmann, S. Bellmann, C. Werner, R. Schroder, N. Schutze, and G. Alber
IL-12p40-Dependent Agonistic Effects on the Development of Protective Innate and Adaptive Immunity Against Salmonella Enteritidis
J. Immunol., November 1, 2001; 167(9): 5304 - 5315.
[Abstract] [Full Text] [PDF]


Home page
J. Leukoc. Biol.Home page
F. Ethuin, C. Delarche, S. Benslama, M.-A. Gougerot-Pocidalo, L. Jacob, and S. Chollet-Martin
Interleukin-12 increases interleukin 8 production and release by human polymorphonuclear neutrophils
J. Leukoc. Biol., September 1, 2001; 70(3): 439 - 446.
[Abstract] [Full Text] [PDF]


Home page
J. Immunol.Home page
K. H. Baek, S. J. Ha, and Y. C. Sung
A Novel Function of Phosphorothioate Oligodeoxynucleotides as Chemoattractants for Primary Macrophages
J. Immunol., September 1, 2001; 167(5): 2847 - 2854.
[Abstract] [Full Text] [PDF]


Home page
Infect. Immun.Home page
L. Del Rio, A. J. Buendia, J. Sanchez, M. C. Gallego, M. R. Caro, N. Ortega, J. Seva, F. J. Pallares, F. Cuello, and J. Salinas
Endogenous Interleukin-12 Is Not Required for Resolution of Chlamydophila abortus (Chlamydia psittaci Serotype 1) Infection in Mice
Infect. Immun., August 1, 2001; 69(8): 4808 - 4815.
[Abstract] [Full Text] [PDF]


Home page
J. Immunol.Home page
U. Grohmann, M. L. Belladonna, C. Vacca, R. Bianchi, F. Fallarino, C. Orabona, M. C. Fioretti, and P. Puccetti
Positive Regulatory Role of IL-12 in Macrophages and Modulation by IFN-{{gamma}}
J. Immunol., July 1, 2001; 167(1): 221 - 227.
[Abstract] [Full Text] [PDF]


Home page
JEMHome page
M. J. Walter, N. Kajiwara, P. Karanja, M. Castro, and M. J. Holtzman
Interleukin 12 P40 Production by Barrier Epithelial Cells during Airway Inflammation
J. Exp. Med., February 5, 2001; 193(3): 339 - 352.
[Abstract] [Full Text] [PDF]


Home page
J. Immunol.Home page
S. W. Lee, M. K. Song, K. H. Baek, Y. Park, J. K. Kim, C. H. Lee, H.-K. Cheong, C. Cheong, and Y. C. Sung
Effects of a Hexameric Deoxyriboguanosine Run Conjugation into CpG Oligodeoxynucleotides on Their Immunostimulatory Potentials
J. Immunol., October 1, 2000; 165(7): 3631 - 3639.
[Abstract] [Full Text] [PDF]


Home page
J. Immunol.Home page
H. Kahlert, E. Grage-Griebenow, H.-T. Stuwe, O. Cromwell, and H. Fiebig
T Cell Reactivity with Allergoids: Influence of the Type of APC
J. Immunol., August 15, 2000; 165(4): 1807 - 1815.
[Abstract] [Full Text] [PDF]


Home page
Infect. Immun.Home page
S. Epelman, T. F. Bruno, G. G. Neely, D. E. Woods, and C. H. Mody
Pseudomonas aeruginosa Exoenzyme S Induces Transcriptional Expression of Proinflammatory Cytokines and Chemokines
Infect. Immun., August 1, 2000; 68(8): 4811 - 4814.
[Abstract] [Full Text] [PDF]


Home page
J. Immunol.Home page
A. Pagenstecher, S. Lassmann, M. J. Carson, C. L. Kincaid, A. K. Stalder, and I. L. Campbell
Astrocyte-Targeted Expression of IL-12 Induces Active Cellular Immune Responses in the Central Nervous System and Modulates Experimental Allergic Encephalomyelitis
J. Immunol., May 1, 2000; 164(9): 4481 - 4492.
[Abstract] [Full Text] [PDF]


This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow Request Permissions
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Ha, S. J.
Right arrow Articles by Sung, Y. C.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Ha, S. J.
Right arrow Articles by Sung, Y. C.


HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS