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Department of Experimental Medicine, University of Perugia, Perugia, Italy
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Abstract |
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 Top Abstract IntroductionMaterials and MethodsResultsDiscussionReferences |
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Introduction |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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-galactosidase from Escherichia coli
(8). These studies have demonstrated that
CD4+ T cells control CD8+ T
cell reactivity to such Ag (7, 8), emphasizing distinct
roles for Th1 and Th2 cells in tumor eradication (7). Cell-mediated immunity involving CD8+ lymphocytes is effective in mediating rejection of murine mastocytoma cells bearing P815AB, a tumor-associated and self Ag showing similarity to tumor-specific shared Ag in humans (9, 10, 11). Although this Ag may act as an efficient target for class I-restricted responses in immunized mice, neither P815AB expressed on tumor cells nor a related synthetic nonapeptide will activate unprimed CD8+ cells for in vivo reactivity, presumably as a result of poor ability of P815AB to recruit CD4+ T cells to the afferent response (12, 13). However, effective priming to P815AB is achieved by immunizing mice with dendritic cells exposed in vitro to recombinant IL-12 and P815AB-related peptides (14, 15, 16, 17). Under such conditions, an immune response is initiated in vivo that involves both class II-restricted (helper) and class I-restricted epitopes of P815AB, and can be detected in vivo to nonameric P815AB (12, 13), the minimal core peptide for CTL recognition (10).
In the present study, we have used this immunizing strategy to induce
CD4+ T cell clones recognizing the helper
epitopes of P815AB. Two representative clones, one releasing high
levels of IFN-
(Th1 type) and the other high levels of IL-4 (Th2
type), were assayed for antitumor activity when transferred into
recipient hosts challenged with P815AB-expressing tumor cells. The
prophylactic or postchallenge administration of either clone was found
to result in a tumor eradication that was dependent on the de novo
generation of P815AB-specific CD8+ T cells
in vivo.
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Materials and Methods |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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DBA/2J (H-2d) mice were obtained from Charles River Laboratories (Calco, Milan, Italy). Male mice were used at the age of 2–4 mo. Mastocytoma P815 was cultured in DMEM supplemented with 10% FCS and incubated at 37°C in an 8% CO2 atmosphere. Various clones of P815 were used in this study: P1, a tumorigenic clone of P815; P1.204, a P815AB-negative variant obtained from an in vivo escaping tumor population and carrying a deletion of gene P1A; and P1.HTR, the highly transfectable variant of P1 (18, 19).
Peptides, cytokines, and Abs
Peptides were synthesized as previously described (12, 17), purified by means of reversed-phase HPLC, and characterized
by amino acid analysis. The single letter code sequence of the peptides
used in this study is as follows: P815AB.9, LPYLGWLVF; P815AB.12,
EILPYLGWLVFA; and OVA-(323-339), ISQAVHAAHAEINEAGR. Murine
rIL-12 was a generous gift from B.
Hubbard (Genetics Institute, Cambridge, MA). IL-12 was 98.8% pure, as
assessed by SDS-PAGE, and endotoxin contamination was <0.9 endotoxin
units/mg on Limulus amebocyte assay. The specific activity
of the purified rIL-12 preparation, measured as the ability to
stimulate proliferation in human PHA-activated blasts, was 3.1 x
106 U/mg. Human rIL-2 was obtained from Chiron
(Emeryville, CA). Murine rIFN- and rIL-4 were purchased from
PharMingen (San Diego, CA). PE-labeled antimouse CD8
and IFN-,
and FITC-labeled antimouse CD4 and IL-4 were obtained from PharMingen.
Isotype-matched irrelevant mAbs were used as controls in the analysis
of CD4/CD8 Ag expression. Antimouse IL-4 mAbs 11B11 and biotinylated
BVD6-24G2 and antimouse IFN- mAbs R4-6A2 and biotinylated XMG1.2
were purchased from PharMingen. The anti-I-Ad
(MK-D6, mouse IgG2a) mAb was purified from hybridoma culture
supernatant (17). Source and characteristics of the
monoclonal rat-mouse hybrid cell line producing 53.6.72 (IgG2a
anti-CD8) mAb were as described previously (14), and
Abs were purified by means of affinity chromatography.
Generation of helper T cell clones
Five x 106 highly purified splenic
dendritic cells (16), >96% CD11c+,
were incubated overnight with 100 ng/ml rIL-12 (14, 15, 16)
and pulsed with 5 µM P815AB.12 peptide at 37°C for 2 h. Cells
were then irradiated (30 Gy) and washed, and each mouse received an
intrafootpad injection of 5 x 105
peptide-pulsed dendritic cells. After 7 days, popliteal lymph nodes
were harvested and T cells were plated at 1 x
106 cells/well in 24-well plates in complete
media (20) containing 50% of supernatant from secondary
mixed leukocyte culture as a source of T cell growth factors.
Irradiated syngeneic splenocytes pulsed with 5 µM P815AB.12 peptide
were added at 6 x 106 cells/well every
week. After 2 wk, contaminating CD8+ T cells were
removed using a positive selection column and CD8 MicroBeads
(Miltenyi Biotec, Bergish Gladbach, Germany). The recovered
CD4+ T cells, >99% pure, were cloned by
limiting dilution. The resulting clones were maintained by weekly
restimulation of 1 x 105 cells with 5 µM
P815AB.12 peptide and 6 x 106 irradiated
spleen cells, in complete medium containing 40 U/ml human rIL-2.
Cytokine activity and intracellular cytokine expression
CD4+ T cells (105)
were cultured with peptide-pulsed syngeneic irradiated spleen cells
(106) in 96-well plates. After 48 h,
supernatants were harvested and cytokine contents were evaluated by
sandwich ELISA. The IFN- activity was determined using R4-6A2 and
biotinylated XMG1.2, whereas IL-4 measurements involved the use of mAb
11B11 and biotinylated BVD6-24G2. The sensitivity limit was 
20 pg/ml
for both cytokines assayed by ELISA. To evaluate the cytoplasmic
IFN- and IL-4 contents of T cell clones, cells stimulated with
immobilized anti-CD3 mAb for 5 h in the presence of brefeldin
A (1 µg/ml, during the final 1.5 h) were stained by the
paraformaldehyde-saponin procedure, as described previously
(21). After extensive washing in immunofluorescence buffer
(PBS with 3% FCS and 0.02% NaN3), cells were
fixed in 2% paraformaldehyde for 10 min at room temperature, washed
again, and incubated with PE-labeled anti-IFN- and FITC-labeled
anti-IL-4 Abs in immunofluorescence buffer containing 0.3% saponin
for 30 min on ice. Isotype-matched irrelevant mAbs were used as
controls in the analysis of intracellular IFN-/IL-4 expression.
Delayed-type hypersensitivity assay
An assay system for measuring the delayed-type hypersensitivity (DTH)3 response to tumor Ag was employed (22) in which 106 irradiated P1 cells and 105 CD4+ T cells were inoculated into the left footpads of naive mice, whereas the right footpads received 106 irradiated P1-204 control cells and 105 CD4+ T cells. The DTH reaction was recorded at different times after challenge by measuring the footpad thickness using a digital micrometer (Mitutoyo, Tokyo, Japan). The results were expressed as the increase in footpad thickness (left hind) over that of the control (right hind) counterpart. Data are the means ± SD of six to eight mice per group.
In vivo tumor experiments
Cultured tumor cells were washed three times with PBS and resuspended in PBS for implantation into mice. Living cells (106) were injected in 100 µl via a 27-gauge needle on the left flank. Tumor size was assessed twice per week using calipers, the longest and the shortest diameters were measured, and a mean was calculated. Data from groups of eight mice were analyzed at each time point, and a mean and a SE were determined. Measurements were continued for 4 wk. F2 or F76 T cells (5 x 106/injection) were i.v. transferred into mice either 3 days before tumor challenge (prophylactic administration) or on days 7, a time when the tumor mass became palpable (4–6 mm), 14, and 21 after tumor challenge (postchallenge administration). In selected experiments, mice also received IL-12-treated, P815AB.9-pulsed dendritic cells (5 x 105) on day 6 after tumor challenge. For CD8+ T cell depletion, mice received multiple i.p. injections of purified anti-CD8 mAb: once before tumor challenge (1 mg on day -1) and twice a week for 3 wk after tumor challenge (0.25 mg/injection). Control groups for mAb treatment received equal amounts of affinity-purified rat IgG (Zymed, San Francisco, CA).
CTL generation
Cytolytic assays were performed as described elsewhere (23). Briefly, splenocytes (5 x 106) were harvested 20 days after in vivo tumor challenge and stimulated with irradiated (10,000 Gy) P1 cells (2.5 x 105) in a volume of 2 ml. After 5 days, responder cells were recovered and tested for lytic activity against 2 x 103 51Cr-labeled tumor target cells according to standard conditions. Results were expressed as the mean of quadruplicate samples at different E:T ratios.
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Results |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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To study the effect of Ag-specific CD4+ T
cells on the function of endogenous CD8+ T cells
recognizing the same tumor Ag, we generated CD4+
T cell populations from mice immunized with dendritic cells treated in
vitro with IL-12 and pulsed with a P815AB-related dodecameric peptide
(P815AB.12). Lymph node cells were restimulated in vitro with the
eliciting peptide and then enriched for CD4+ T
cells. The resulting T cell line was cloned by limiting dilution,
yielding several types of specific clones, including those that
secreted predominantly IFN- and those that secreted predominantly
IL-4 (Fig. 1
A). Of >30
clones characterized in detail, F76, which appeared to be
CD4+ and expressed intracellular IFN- by FACS
analysis, and F2, also CD4+ but expressing IL-4
(Fig. 1, B and C), grew continuously for over 12
mo, allowing for further study. Functional characterization confirmed
that F76 was Th1-type and mediated Th1-associated effector responses in
vivo, in contrast to Th2-type F2. When admixed with P815AB-expressing
tumor cells before intrafootpad injection, F76 elicited a classical DTH
response that peaked at about 12 h postchallenge. No such response
was observed in mice injected with F2 cells (Fig. 1D). In
the latter animals, a negligible nonspecific DTH was detected that did
not increase in the presence of specific Ag.
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and IL-4 were also
exhibited by F76 and F2 clones when cocultured in vitro with class
II-negative, P815AB-expressing P1.HTR cells in the presence of
splenocytes as APC (Fig. 1
E), thus confirming that P815AB is
efficiently processed and presented by professional APC
(24). In addition, Fig. 1E shows that cytokine
production by the two clones was specific, being negligible in response
to an OVA peptide; furthermore, the helper epitopes recognized by the
CD4+ cells induced by vaccination with P815AB.12
were also present in P815AB.9, the minimal core peptide for CTL
recognition. We have previously shown that P815AB.9 does possess class
II-restricted epitopes that appear nevertheless to be suboptimal for
priming in vivo in the absence of immunoadjuvants (15, 17). Finally, cytokine secretion in response to specific Ag in
vitro was restricted by I-Ad class II molecules.
In experiments not reported here, we also found that neither clone was
cytotoxic in vitro to radiolabeled P815AB-expressing (P1) tumor
cells. Antitumor effects of P815AB-specific CD4+ T cell clones administered before challenge with P815AB-expressing tumor cells
To evaluate whether the prophylactic injection of F76 and F2
CD4+ T cell clones could mediate tumor
regression, prospective recipients of a s.c. challenge with
P815AB-expressing (P1.HTR) cells or an Ag-loss variant (P1.204) were
administered an i.v. injection of either clone. Control mice received
PBS. Tumor growth was monitored in terms of mean tumor diameter
assessed at different times postchallenge. All recipients of F76 cells
rejected P1.HTR but not P1.204 tumor cells. Complete rejection of
P1.HTR but not P1.204 cells was observed in 60–80% of mice receiving
F2 clone cells (representative experiment shown in Fig. 2, out of five performed with analogous
results). Histochemical analysis showed that no significant lymphocyte
infiltration was observed over time in control P1.HTR tumor tissue
preparations in the absence of cell transfer; in contrast, at 10–14
days after tumor challenge, marked and qualitatively comparable
lymphocyte infiltrations were present in tumor tissue of mice that had
been treated with F76 or F2 cells (data not shown).
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In our immunization model system, dendritic cells likely present
P815AB.12 in the context of class II molecules. However, the
interaction of host APC with Ag-specific CD4+ T
cells could make APC capable of stimulating naive, endogenous
CD8+ cytotoxic T cells, which might then function
as specific effectors capable of lysing tumor. Such a mechanism has
previously been shown to be at work in a system with a model tumor Ag
(8). To directly assess the induction of P815AB-specific
host CD8+ T cells, fresh splenocytes from
tumor-bearing mice that had been treated with the F76 or F2 clones were
harvested 20 days after tumor implantation and were cocultured with P1
cells. The recovered cells were assayed for cytotoxic activity to
P815AB-positive (P1) or -negative (P1.204) cells. Fig. 3 shows that potent
CD8+ T cell responses were induced to P1 cells by
the immunotherapy regimen that would result in a 100% cure rate,
namely, the adoptive transfer of F76 cells. Although less remarkable, a
cytotoxic response was also induced by transfer of the F2 clone, a
procedure that would result in cure of 60–80% mice, as illustrated
above. No cytotoxic activity was displayed to P815AB-negative variant
cells as target cells in the cytotoxicity assay. Control cultures not
reported in Fig. 3 showed that no cytotoxic activity was generated by
coculturing tumor cells with splenocytes from tumor-bearing mice
unexposed to F76 or F2 cells.
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30%
tumor-challenged mice gave negligible responses (data not shown).
Interestingly, these mice had the largest tumor diameters.
To directly assess the possible requirement of
CD8+ T cells in the protective effect induced by
transfer of F76 or F2 cells, we resorted to serologic ablation of
CD8+ cells by means of specific Ab. Fig. 4 shows that the depletion of
CD8+ lymphocytes concurrent with adoptive
transfer followed by tumor challenge completely ablated the protective
effect of T cell clone transfer.
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To evaluate whether the CD4+ T cell clones
could mediate tumor eradication when injected after challenge, the
P1.HTR tumor was injected s.c. and allowed to establish for 7 days, a
time when it became palpable. The tumor-bearing mice were then treated
with an i.v. injection of 5 x 106 F76 or F2
cells. Fig. 5A shows that cure
of mice was only achieved by transfer of F76 cells, whereas, under
these conditions of treatment, immunotherapy with F2 cells resulted in
no significant beneficial effect in terms of tumor growth and survival
rate of the tumor-challenged mice. This suggested that the F2 cells by
themselves might not be enough to induce a sufficient and/or
appropriate immune response when administered postchallenge. We thus
examined the effect of multiple injections of F76 or F2 cells, either
alone or in combination with transfer of dendritic cells preexposed to
IL-12 and P815AB.9 (Fig. 5B). When mice were treated on days
7, 14, and 21 with F76 or F2 cells, the recipients of the former cells
exhibited accelerated rejection of the implanted tumor; among
recipients of three injections of F2 cells, <40% survived challenge.
However, on combining lymphocyte transfer with dendritic cells
administered on day 6, the vast majority of F2 cell recipients resisted
challenge, according to a growth and rejection pattern of the P1.HTR
tumor similar to that observed in the recipients of a single injection
of F76 cells. Interestingly, no effect was displayed by peptide-pulsed
dendritic cells administered 6 days after challenge, as opposed to the
complete protection observed when transfer precedes tumor challenge
(13). Most strikingly, all mice cured by immunotherapy
with the F76 clone or a combination of F2 plus dendritic cells were
later (i.e., at 4–6 wk) found to resist challenge with large inocula
of P1.HTR cells. Under the latter conditions of testing, a peculiar
growth and rejection pattern of the implanted tumor was observed in
that no initial tumor development was observed as in the primary
challenge.
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Discussion |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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Tumor-specific shared Ag in humans, such as members of the MAGE, BAGE,
and GAGE families found in melanoma and other cell types, derive from
nonmutated self proteins and have an expression pattern similar to
P815AB, a poorly immunogenic tumor-associated Ag of murine mastocytoma
cells (26). We have generated Th cell clones specific for
P815AB by immunizing mice with syngeneic dendritic cells activated with
IL-12 in vitro and pulsed with a synthetic P815AB-related peptide
(13). We have previously shown that under these conditions
of priming, an immune response is initiated in the host which is
directed to both class II-restricted and class I-restricted epitopes of
P815AB (15). One of the resulting
CD4+ cell clones, F76, produced high levels of
IFN- but not IL-4 in vitro and mediated a classical DTH response in
vivo when admixed with antigenically relevant tumor cells (Fig. 1). It
could thus be defined functionally as a Th1-type clone. In contrast,
F2, which secreted high levels of IL-4 but not of IFN- in vitro in
response to specific Ag, failed to mediate DTH in vivo (Fig. 1) and
could thus be defined as a Th2-type clone (27). Both
clones secreted the respective cytokine pattern when stimulated in
vitro with class II-negative, P815AB-bearing cells in the presence of
APC, presumably recognizing helper epitopes also present in P815AB.9
(Fig. 1E), the minimal core peptide for CTL recognition
(10, 28).
When administered i.v. to prospective recipients of a s.c. challenge
with P815AB-positive cells, both Th1 and Th2 cells prevented tumor
growth and lethality in the totality (F76) or the majority (F2) of the
tumor-challenged mice (Fig. 2). In a recent report using Th1 and Th2
cell lines from OVA-specific TCR-transgenic mice in combination with
OVA gene-transfected tumor cells, Th1 and Th2 cells were found to
mediate tumor regression. However, the CD4+ T
cells in that system appeared to act through distinct mechanisms,
namely, induction of cellular immunity for Th1 cells and tumor necrosis
for Th2 cells. Another important difference between Th1 and Th2 cell
therapy in that model is that Th1 therapy was able to induce a strong
immunological memory which was suitable for CTL generation and was
associated with resistance against rechallenge with parental tumor
cells (7). In our model system with P815AB, histochemical
analysis of tumor tissues from the recipients of Th1 or Th2 cells did
not suggest the involvement of distinct mechanisms in tumor eradication
by either type of T cell clone (data not shown). In addition, the
rejection of P815AB-expressing tumor cells initiated by postchallenge
transfer of either clone was associated with strong immunological
memory, as evidenced by the growth and rejection pattern of the
P815AB-expressing tumor used for rechallenge. It has been suggested
that the distinct antitumor activities mediated by OVA-specific Th1 and
Th2 cells can be traced to different cell adhesion interactions
involved in the migration of these cells into tumor tissues across
endothelia. Yet, unknown mechanisms appear to be involved in
Th2-induced tumor necrosis, although recruitment of eosinophils and
macrophages could be a likely possibility (29). Shen and
Fujimoto (25) also described regression of a
methylcholanthrene-induced sarcoma mediated by a Th2-type clone. No
evidence was obtained in that model for either a direct cytotoxic
activity of the CD4+ T cells or recruitment of
host eosinophils to the antitumor effector response. It was rather
hypothesized that the transferred CD4+ T cells
would migrate into tumor sites to be restimulated by APC in tumor
tissue. This would lead locally to the secretion of cytokines necessary
for CTL priming.
Although the mechanisms underlying the therapeutic activity of Th1 and
Th2 cells in our model system are unclear, the antitumor effect
initiated by transfer of either clone was associated with the detection
of CTL activity in vitro (Fig. 3) and required the presence of
CD8+ T cells in vivo (Fig. 4). An absolute
requirement for host CD8+ T cells has been found
not only in the model system with the Th2 cell clone mentioned above
(25) but also in the immunotherapy with model tumor Ag. In
particular, the therapeutic efficacy of Th2 cells in conjunction with
tumor cells expressing OVA Ag has been suggested to be mediated by the
recruitment of Ag-nonspecific CD8+ killer T cells
as the final effectors of the response (7). In the case of
the Th1 clone recognizing Ag on a -galactosidase-transduced tumor
(8), it has been suggested that the antitumor effect of
CD4+ T cells occurs through an indirect mechanism
involving the recruitment of host Ag-specific
CD8+ T cells. It has been proposed that the
interaction of host APC with Ag-specific CD4+ T
cells can make the former cells capable of stimulating naive,
endogenous CD8+ cytotoxic T cells, which may then
function as specific effectors capable of destroying tumor. It is
likely that CD8+ T cells are important effector
cells in our model of Th1 and Th2 cell therapy, because Ag-specific CTL
activity could be detected in vitro, and depletion of
CD8+ T cells abrogated the therapeutic effect of
cell transfer. Interestingly, the higher efficacy of F76 cell transfer
was associated with higher levels of cytotoxic activity generated in
vitro. In experiments not reported here, we also found that
CD8+ T cell responses were not induced in
nontumor-bearing mice receiving F76 or F2 cells when their splenocytes
were stimulated in vitro with P815AB-expressing tumor cells.
CD4+ T cells are known to interact with class II-expressing host cells, especially dendritic cells, affecting their ability to modulate different components of the immune system. Presentation of P815AB by dendritic cells and host production of IL-12 are required for the initiation of a class I-restricted response to P815AB that is dependent on the presence of an intact CD4+ cell compartment (12, 14). In our adoptive transfer model with CD4+ cells, it is possible that the transferred cells specifically interact with dendritic cells at the tumor site, resulting in CD40-CD40 ligand interactions and production of IL-12. The cytokine may further activate the dendritic cell in an autocrine fashion (16, 30) and contribute to the activation of proximate CD8+ T cells recognizing class I-restricted epitopes of P815AB on the dendritic cell. This would be consistent with our finding that preactivation in vitro of P815AB-pulsed myeloid dendritic cells with IL-12 results in the development of strong class I-restricted responses when the dendritic cells are transferred into recipient hosts (31).
The adoptive transfer of CD4+ T cells was also
found to treat established tumor in our model system (Fig. 5). However,
whereas the Th1 clone was fully capable of eradicating tumor, the Th2
clone required repeated injections and optimal protection was only
achieved by combining Th2 cell transfer with the injection of
peptide-pulsed dendritic cells. The combined effects of T cell transfer
and dendritic cell transfer under conditions in which neither treatment
alone would be effective further substantiate the hypothesis of an
interaction taking place in vivo between the transferred T cells and
dendritic cells, resulting in effective host production of endogenous
IL-12. The hypothesis of a primary role of dendritic cell
"conditioning" (8, 32, 33, 34), as mediated by a CD40
engagement that results in up-regulation of CD80/CD86, class I/class
II, and IL-12 expression, would be consistent with the finding of
therapeutic efficacy of both Th1 and Th2 cells, largely independent of
their cytokine secretion profile. This would imply that quantitative
rather than qualitative differences may characterize the antitumor
immunity mediated by Th1 and Th2 cell clones. From the data in Fig. 2, it would appear that there is a quantitative inferiority of the Th2
clone relative to Th1 cells in promoting tumor rejection. Preliminary
experiments based on transfer of graded numbers of either clone cells
seem to suggest that the difference is indeed quantitative.
Independent of the cytokine secretion profiles, the adoptive transfer of CD4+ cells has also been reported to eradicate established tumors in a variety of experimental models (35, 36, 37). In most of these systems, the therapeutic activity of CD4+ T cells was traced to activation of NK or macrophage effector cells or to direct lysis of class II-expressing tumor cells. In addition, specific Th cell requirement for optimal CTL induction was also found when the tumor cells were class II negative (38). Although our Th cell clones lacked direct cytotoxic activity in vitro to antigenically relevant target cells, it is possible that one or more of these mechanisms may contribute to the therapeutic efficacy of Th cell clones. However, our present data suggest that activation of endogenous CD8+ effector cells is a major therapeutic effect initiated by CD4+ T cell transfer. Although CD8+ T cells have been used successfully to transfer antitumor resistance in adoptive immunotherapy models (39, 40), it has been recently found that transgenic mice that express the TCR from a CTL clone recognizing P815AB are no more resistant to a P815AB-bearing plasmacytoma than nontransgenic littermates (41). Our data suggest that the activation of specific CD8+ T cells by CD4+ T cells may be most efficient when cells recognize the same Ag presented by dendritic cells in the context of both class I and class II molecules. The effect would require an action on dendritic cells, perhaps largely mediated by CD40-CD40 ligand interactions, leading to enhanced ability of the dendritic cell to stimulate responder CD8+ T cells. Finally, the production of IL-12 by dendritic cells at the tumor site may be a critical step with the cytokine acting at both the dendritic cell (16) and T cell (42) levels. Lack or suppression (43) of inflammatory signals in a growing tumor could explain the failure of the host to locally recruit helper and cytotoxic cells to the antitumor response. However, provision of specific CD4+ T cells by adoptive transfer or by activation in vivo after vaccination might lead to the de novo induction of CD8+ T cell reactivity.
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Acknowledgments |
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Footnotes |
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2 Address correspondence and reprint requests to Dr. Paolo Puccetti, Department of Experimental Medicine, Pharmacology Section, University of Perugia, Via del Giochetto, I-06122 Perugia, Italy.
3 Abbreviation used in this paper: DTH, delayed-type hypersensitivity.
Received for publication June 22, 2000. Accepted for publication August 15, 2000.
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References |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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B and primes DC for IL-12 production. Immunity 9:315.[Medline]
- dendritic cells to enhance presentation of a tumor peptide in vivo. J. Immunol. 163:3100. inhibits presentation of a tumor/self peptide by CD8- dendritic cells via potentiation of the CD8+ subset. J. Immunol. 165:1357.This article has been cited by other articles:
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S.-i. Hiraoka, N. Takeuchi, Y. Bian, H. Nakahara, M. Kogo, K. Dunussi-Joannopoulos, S. Wolf, S. Ono, and H. Fujiwara B7.2-Ig fusion proteins enhance IL-4-dependent differentiation of tumor-sensitized CD8+ cytotoxic T lymphocyte precursors Int. Immunol., August 1, 2005; 17(8): 1071 - 1079. [Abstract] [Full Text] [PDF]
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T. Tsuji, M. Yasukawa, J. Matsuzaki, T. Ohkuri, K. Chamoto, D. Wakita, T. Azuma, H. Niiya, H. Miyoshi, K. Kuzushima, et al. Generation of tumor-specific, HLA class I-restricted human Th1 and Tc1 cells by cell engineering with tumor peptide-specific T-cell receptor genes Blood, July 15, 2005; 106(2): 470 - 476. [Abstract] [Full Text] [PDF]
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C. Orabona, M. L. Belladonna, C. Vacca, R. Bianchi, F. Fallarino, C. Volpi, S. Gizzi, M. C. Fioretti, U. Grohmann, and P. Puccetti Cutting Edge: Silencing Suppressor of Cytokine Signaling 3 Expression in Dendritic Cells Turns CD28-Ig from Immune Adjuvant to Suppressant J. Immunol., June 1, 2005; 174(11): 6582 - 6586. [Abstract] [Full Text] [PDF]
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G. S. D. Reid, K. She, L. Terrett, M. R. Food, J. D. Trudeau, and K. R. Schultz CpG stimulation of precursor B-lineage acute lymphoblastic leukemia induces a distinct change in costimulatory molecule expression and shifts allogeneic T cells toward a Th1 response Blood, May 1, 2005; 105(9): 3641 - 3647. [Abstract] [Full Text] [PDF]
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N. Yamaguchi, S.-i. Hiraoka, T. Mukai, N. Takeuchi, X.-Y. Zhou, S. Ono, M. Kogo, K. Dunussi-Joannopoulos, V. Ling, S. Wolf, et al. Induction of Tumor Regression by Administration of B7-Ig Fusion Proteins: Mediation by Type 2 CD8+ T Cells and Dependence on IL-4 Production J. Immunol., February 1, 2004; 172(3): 1347 - 1354. [Abstract] [Full Text] [PDF]
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E. H. Slager, M. Borghi, C. E. van der Minne, C. A. Aarnoudse, M. J. E. Havenga, P. I. Schrier, S. Osanto, and M. Griffioen CD4+ Th2 Cell Recognition of HLA-DR-Restricted Epitopes Derived from CAMEL: A Tumor Antigen Translated in an Alternative Open Reading Frame J. Immunol., February 1, 2003; 170(3): 1490 - 1497. [Abstract] [Full Text] [PDF]
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V. Bronte, P. Serafini, C. De Santo, I. Marigo, V. Tosello, A. Mazzoni, D. M. Segal, C. Staib, M. Lowel, G. Sutter, et al. IL-4-Induced Arginase 1 Suppresses Alloreactive T Cells in Tumor-Bearing Mice J. Immunol., January 1, 2003; 170(1): 270 - 278. [Abstract] [Full Text] [PDF]
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 T. Tatsumi, L. S. Kierstead, E. Ranieri, L. Gesualdo, F. P. Schena, J. H. Finke, R. M. Bukowski, J. Mueller-Berghaus, J. M. Kirkwood, W. W. Kwok, et al. Disease-associated Bias in T Helper Type 1 (Th1)/Th2 CD4+ T Cell Responses Against MAGE-6 in HLA-DRB10401+ Patients With Renal Cell Carcinoma or Melanoma J. Exp. Med., September 2, 2002; 196(5): 619 - 628. [Abstract] [Full Text] [PDF]
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F. Fallarino, U. Grohmann, C. Vacca, R. Bianchi, M. C. Fioretti, and P. Puccetti CD40 Ligand and CTLA-4 Are Reciprocally Regulated in the Th1 Cell Proliferative Response Sustained by CD8+ Dendritic Cells J. Immunol., August 1, 2002; 169(3): 1182 - 1188. [Abstract] [Full Text] [PDF]
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H. Huang, F. Li, J. R. Gordon, and J. Xiang Synergistic Enhancement of Antitumor Immunity with Adoptively Transferred Tumor-specific CD4+ and CD8+ T Cells and Intratumoral Lymphotactin Transgene Expression Cancer Res., April 1, 2002; 62(7): 2043 - 2051. [Abstract] [Full Text] [PDF]
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F. Fallarino, C. Vacca, C. Orabona, M. L. Belladonna, R. Bianchi, B. Marshall, D. B. Keskin, A. L. Mellor, M. C. Fioretti, U. Grohmann, et al. Functional expression of indoleamine 2,3-dioxygenase by murine CD8{alpha}+ dendritic cells Int. Immunol., January 1, 2002; 14(1): 65 - 68. [Abstract] [Full Text] [PDF]
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H. M. Zarour, B. Maillere, V. Brusic, K. Coval, E. Williams, S. Pouvelle-Moratille, F. Castelli, S. Land, J. Bennouna, T. Logan, et al. NY-ESO-1 119-143 Is a Promiscuous Major Histocompatibility Complex Class II T-Helper Epitope Recognized by Th1- and Th2-Type Tumor-reactive CD4+ T Cells Cancer Res., January 1, 2002; 62(1): 213 - 218. [Abstract] [Full Text] [PDF]
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C. Meyer zum Buschenfelde, J. Metzger, C. Hermann, N. Nicklisch, C. Peschel, and H. Bernhard The Generation of Both T Killer and Th Cell Clones Specific for the Tumor-Associated Antigen HER2 Using Retrovirally Transduced Dendritic Cells J. Immunol., August 1, 2001; 167(3): 1712 - 1719. [Abstract] [Full Text] [PDF]
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U. Grohmann, F. Fallarino, R. Bianchi, M. L. Belladonna, C. Vacca, C. Orabona, C. Uyttenhove, M. C. Fioretti, and P. Puccetti IL-6 Inhibits the Tolerogenic Function of CD8{{alpha}}+ Dendritic Cells Expressing Indoleamine 2,3-Dioxygenase J. Immunol., July 15, 2001; 167(2): 708 - 714. [Abstract] [Full Text] [PDF]
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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]
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U. Grohmann, F. Fallarino, S. Silla, R. Bianchi, M. L. Belladonna, C. Vacca, A. Micheletti, M. C. Fioretti, and P. Puccetti CD40 Ligation Ablates the Tolerogenic Potential of Lymphoid Dendritic Cells J. Immunol., January 1, 2001; 166(1): 277 - 283. [Abstract] [Full Text] [PDF]
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