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* Institute of Immunology, University of Vienna Medical School, Vienna, Austria;
Department of Pathology, Karl Franzens University, Graz, Austria; and
Novartis Research Institute, Vienna, Austria
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Abstract |
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, IL-10, and IL-12. Moreover, the well-established inhibitory function of IL-10-treated DC could be reverted with mAb DF272. Even T cells, anergized because of stimulation with IL-10-treated DC, could be reactivated and induced to proliferate upon stimulation with mAb DF272-treated DC. Furthermore, mAb DF272-treated DC favored the induction of a type-1 cytokine response in T cells and inhibited IL-10 production. By using a retrovirus-based cDNA expression library generated from DC, we cloned and sequenced the mAb DF272-defined cell surface receptor and could demonstrate that it is identical with B7-H1 (programmed death-1 ligand), a recently identified new member of the B7 family of costimulatory molecules. Our results thus demonstrate that the mAb DF272-defined surface molecule B7-H1 represents a unique receptor structure on DC that might play a role in the induction and maintenance of T cell anergy. |
Introduction |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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Dendritic cells (DC) 3 are professional APC that are specialized for the initiation and regulation of T cell immunity (3, 4, 5). The efficacy of DC in activating T cells appears to correlate with quantitative aspects. For example, MHC products and MHC-peptide complexes are expressed 10- to 100-fold higher on DC than on other APC, like B cells or monocytes (6, 7). DC also express high levels of a plethora of known accessory molecules that interact with receptors on T cells to enhance adhesion and signaling, e.g., B7.1 (CD80), B7.2 (CD86), LFA-3 (CD58), and ICAM-1 (CD54). Although these prominent accessory molecules are important for mediating T cell activation, their ubiquitous expression on multiple APC types suggests that additional molecules contribute to the extraordinary stimulatory and regulatory capacity of DC. The recent identification of additional DC-specific coreceptor structures such as DC-SIGN (8) and B7-DC (9) supports the idea that DC express specific accessory molecules.
For the identification of such structures we combined classical hybridoma technology with a selective functional screening approach and a highly efficient retroviral expression cloning strategy, which we have recently established (10, 11). With this approach, we discovered an accessory receptor on DC that promotes the induction and maintenance of anergy in T cells. It is B7-H1 programmed death-1 ligand (PD-L1), a recently identified new member of the B7 family (12, 13, 14).
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Materials and Methods |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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The cell culture medium RPMI 1640 (Life Technologies, Paisley, Scotland) was supplemented with 2 mM L-glutamine, 100 U/ml penicillin, 100 µg/ml streptomycin, and 10% FCS (Sigma-Aldrich, Vienna, Austria). The ecotropic retroviral packaging cell line Phoenix (a kind gift from G. Nolan (Stanford University, Stanford, CA) and colleagues) was maintained in DMEM containing 2 mM glutamine and 10% FCS. Recombinant human GM-CSF, IL-2, and IL-4 were kindly provided by Novartis Research Institute (Vienna, Austria). IFN-
was a gift from G. R. Adolf (Ernst Boehringer Institut für Arzneimittelforschung, Vienna, Austria). Recombinant human IL-10 was purchased from R&D Systems (Mineapolis, MN). LPS from Eschericha coli (serotype 0127-B8), PHA, ionomycin, and propidium iodide (PI) were obtained from Sigma Chemie (Deisenhofen, Germany). Annexin V was provided by Caltag Laboratories (Burlingame, CA).
Antibodies
mAbs DF272 (IgG1) were generated in our laboratory by immunizing BALB/c mice with monocyte-derived DC from healthy donors. Fab of DF272 were prepared using papain and the recommended protocol from Avidchrom Fab kit (Unisyn, San Diego, CA). All preparations were further purified by affinity chromatography with protein A and size fractionation with fast protein liquid chromatography superdex gel filtration (Pharmacia Biotech, Uppsala, Sweden). Purity of Fab was checked and confirmed with Abs specific for murine Fab (Sigma-Aldrich) or murine IgG1 Abs (Caltag Laboratories), respectively. All reagents and media used in this study contained <10 pg LPS/ml.
The following murine mAbs were also generated in our laboratory: VIAP (calf intestine alkaline phosphatase specific), VIM12 (CD11b), VIM13 (CD14), 4D3 (CD33), 1/47 (MHC class II), and M80 (IgG1) directed against an undefined myeloid cell surface Ag. The CD14 mAb (MEM18) and the CD3 mAb (UCHT-1) were kindly provided by An der Grub (Bio Forschungs, Kaumberg, Austria), and the CD19 mAb (BU12) was a gift from G. Moldenhauer (Department of Molecular Immunology, Heidelberg, Germany). The mAbs CD80 DAL-1 (CD80), BU63 (CD86), and 3G8 (CD16) were purchased from Caltag Laboratories.
Cell preparation
PBMC were isolated from heparinized whole blood of healthy donors by standard density gradient centrifugation with Ficoll-Paque (Pharmacia Biotech). Subsequently, monocytes and T cells were separated by magnetic sorting using the MACS technique (Miltenyi Biotech, Bergisch Gladbach, Germany) as described (15). Monocytes were enriched by using biotinylated CD14 mAbs VIM 13 and MEM 18 (purity >95%). Purified T cells were obtained through negative depletion of CD11b, CD14, CD16, CD19, CD33, and MHC class II positive cells with the respective mAbs. Dendritic cells were generated from CD14+ monocytes cultured in the presence of GM-CSF (50 ng/ml) and IL-4 (100 U/ml) for 7 days. For the generation of "tolerogenic" DC (16), human IL-10 (40 ng/ml) was added to the DC culture on day 3 of differentiation. In some experiments, monocytes were activated with IFN- (100 U/ml), IL-10 (20 ng/ml), or ionomycin (1 µM), and lymphocytes were stimulated with PHA (5 µg/ml) for 24 h at 37°C.
Immunofluorescence analysis
For membrane staining, cells (5 x 105) were incubated for 30 min at 0°C with unlabeled mAbs at a concentration of 20 µg/ml. After washing cells twice with ice-cold PBS containing 1% BSA, binding of the primary mAb was visualized using Oregon Green-conjugated goat anti-mouse Ab from Molecular Probes (Eugene, OR). Cells were then washed three times with PBS/BSA. Membrane fluorescence was analyzed on a FACSCalibur flow cytometer (BD Biosciences, Palo Alto, CA) supported by CellQuest software (BD Biosciences). The exclusion of dead cells was performed by the addition of ethidium bromide (Serva Feinbiochemika, Heidelberg, Germany).
Assessment of apoptosis
DC (1 x 106/ml) were incubated with or without mAb DF272 or with control mAb M80 in 24-well plates (Corning-Costar, Badhoevedorp, The Netherlands) at 37°C for 24 h. Afterward, apoptosis was assessed by staining with FITC-labeled annexin V and PI and performing flow cytometric analysis. Annexin V-positive and PI-negative cells were scored as apoptotic cells.
T cell proliferation assay
For the primary MLR, allogeneic, purified T cells (1 x 105/well) were incubated in 96-well cell culture plates (Corning-Costar) with graded numbers of DC for 4 days. The assay was performed in triplicate, and mAbs were added to the respective cultures at a final concentration of 10 µg/ml. Proliferation of T cells was monitored by measuring [methyl-3H]TdR (ICN Pharmaceuticals, Irvine, CA) incorporation, added on day 5 of culture. Cells were harvested 18 h later, and incorporated [methyl-3H]TdR was detected on a microplate scintillation counter (Packard Instrument, Meriden, CT).
Apoptosis in T cells upon coculture with DC was monitored by staining with annexin V-FITC and PE-labeled CD3 mAb UCHT-1. Apoptosis was calculated as the percentage of annexin V+ cells gated in the CD3+ fraction.
Restimulation of T cells
T cells (1 x 105) were cocultured with allogeneic IL-10-treated DC or untreated DC (1 x 104). After 5 days, T cells were harvested and restimulated with graded numbers of untreated DC from the same donor, as used in the primary MLR. MAbs were added to the respective cultures at a final concentration of 10 µg/ml. Proliferation of T cells was measured 3 days later.
Determination of cytokine production
T cells (106) were cocultured with DC (105) in 24-well plates (Corning-Costar), adding mAbs at a final concentration of 10 µg/ml. After 4 days, the supernatants of primary stimulation cultures were harvested. The cytokines IL-1
, IL-2, IL-4, IL-10, IL-12p40, IL-12p70, and IFN- were measured by sandwich ELISAs using matched-pair Abs (R&D Systems). Abs to human TNF- were from BD PharMingen (San Diego, CA). The lower limit of detection for IL-2 and IL-12p40 was 50 pg/ml; for IL-1, IL-4, IL-10, IL-12p70, TNF-, and IFN-, it was 20 pg/ml. Standards consisted of human recombinant material (R&D Systems). Assays were performed in duplicates according to the recommendations of the manufacturer. Statistical analysis of the measured values was performed by paired Student’s t test.
Retroviral cDNA expression library
A cDNA library from monocyte-derived DCs had been constructed in the retroviral vector CRU5-IRES-GFP (a kind gift from Rigel Pharmaceuticals, San Francisco, CA) featuring CMV promoter-driven expression of the cDNA along with green fluorescence protein (GFP) expression from an internal ribosomal entry site, packaged by Phoenix cells into ecotropic virus particles that were then used to infect target cells. For transfection of the library, ecotropic packaging cells (Phoenix-E) at 50% confluency were harvested by trypsinization, washed, and 6 x 107 were added to a mixture of 100 ml DMEM containing 1% NuSerum culture supplement (Genome Therapeutics, Waltham, MA), 200 µg/ml DEAE-dextran, 25 µM chloroquine diphosphate, and 60 µg of the CRU5 retroviral vector DNA representing the cDNA library. After incubation for 2 h at 37°C, cells were spun down and resuspended in 20 ml DMEM containing 10% FCS and seeded in culture dishes. After 72 h of culture at 32°C, the supernatant was harvested, supplemented with 10 µg/ml hexadimethrine bromide (Sigma-Aldrich), and added to BW5147 target cells (1 x 106/ml) in RPMI 1640 medium containing 10% FCS. Cells were incubated for 24 h (37°C) and then used for the selection procedure.
Isolation of mAb DF272-binding cells from the retrovirus-based cDNA library-transduced cell pool and expression cloning
The retrovirus-infected cell pool (5 x 107) was washed with PBS containing 1% BSA and incubated with mAb DF272 (10 µg/ml) for 30 min on ice. Positive selection was performed by MACS (Miltenyi Biotec) using a RS+ separation column according to the manufacturer’s instructions. The recovered fraction was expanded for further sorting, and single cell cultures were obtained by limiting dilution after >70% of the isolated cells stained positive with mAb DF272. cDNA was recovered from a mAb DF272 reactive single cell clone using Tri-Reagent (Sigma-Aldrich). RT-PCR was performed with Stratascript (Stratagene, La Jolla, CA) and the Advantage-GC polymerase system (Clontech Laboratories, Palo Alto, CA) with primers flanking the multiple cloning site of the retroviral vector CRU5-IRES-GFP. After electrophoresis in Seaplaque Low melting agarose (BioWhittaker, Rockland, ME), the PCR product containing gel fragment was excised, melted, and used directly for ligation into pEF6/V5-HisTOPO T/A cloning vector (Invitrogen, Carlsbad, CA). Plasmid DNA was isolated from transformed DH5 bacteria using a Qiagen Miniprep column according to the manufacturer’s recommendations (Qiagen, Hilden, Germany). Plasmids were then used to transfect 293T cells. The cells were analyzed for mAb DF272 reactivity by indirect immunofluorescence using flow cytometry and fluorescence microscopy 48 h after transfection. Sequencing of cDNA coding for the Ag recognized by mAb DF272 was performed at the VBC-Genomics sequencing facility (Bioscience Research, Vienna, Austria).
Immunohistochemistry staining and tissue preparation
A microtissue array was used to ensure uniform conditions for immunohistochemical staining (17). Representative areas from normal lymph node, spleen, tonsil, thymus, skin, large intestine, skeletal muscle, cardiac muscle, placenta, and lung specimens were marked on H&E stained slides. The corresponding areas were microdissected and embedded in a paraffin block.
Immunohistochemistry
Following deparaffination and rehydration, slides were boiled in a microwave oven in DAKO S 1699 target retrieval solution (DAKO, Glostrup, Denmark). They were rinsed with Tris buffer and incubated with mAb DF272 or isotype-matched control mAb VIAP diluted in DAKO S 2022 Ab diluent for 25 min. Slides were incubated with a secondary Ab (DAKO Chemate Peroxidase/DAB Rabbit/Mouse Kit K5001) for 10 min. Endogenous peroxidase was blocked using 3% H2O2 in methanol. After incubation with the tertiary Ab (DAKO Chemate Peroxidase/DAB Rabbit/Mouse Kit K5001), color development was controlled microscopically, and slides were counterstained using Mayer’s hemalaun.
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Results |
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The aim of this study was to identify cell surface structures on DC with immunoregulatory capacity. For this purpose we immunized mice with human DC to obtain mAbs, which showed reactivity with DC and were capable of modulating the function of DC. mAb DF272 fulfilled these criteria.
Results presented in Fig. 1 demonstrate that mAb DF272 recognizes an Ag expressed on DC but not on resting peripheral blood monocytes or lymphocytes. Expression of the DF272-defined cell surface molecule on DC was further up-regulated upon stimulation of DC. Surprisingly, this effect was not only seen with the maturation-inducing agent LPS (Fig. 1a), but the effect was also observed with the immunosuppressive cytokine IL-10 (Fig. 1b), which usually prevents the induction or up-regulation of typical DC activation markers such as CD83 (16).
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, IL-12, IL-10) in DC nor affected the viability of DC (data not shown). Most importantly, treatment of DC with Fab of mAb DF272 enhanced their stimulatory capability as well as intact Ab (Fig. 3B). Thus, blocking of the DF272-defined Ag on DC with our mAb significantly enhances T cell stimulation of these cells without detectable signs of DC activation.
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The finding that binding of mAb DF272 to DC enhances their stimulatory capacity suggested that DF272 blocks the function of a potentially inhibitory cell surface structure expressed on DC. This idea was further supported by the observation that the immunosuppressive cytokine IL-10 induced expression of the DF272-defined receptor. Treatment with IL-10 has been shown to reduce the stimulatory capacity of DC (5, 16, 18). Thus, we wondered whether the DF272-defined, putative inhibitory receptor might contribute to the anergizing quality of IL-10-treated DC. To test this possibility, we stimulated allogeneic T cells with IL-10-treated DC in the presence of mAb DF272. We found that IL-10-treated DC are poor stimulators of primary, allogeneic T cells (Fig. 4). Under our test conditions, 10 times more IL-10-treated DC were required to achieve a similar level of T cell proliferation compared with untreated DC. However, upon addition of mAb DF272, the poor stimulatory capacity of IL-10-treated DC was reverted, leading to results similar to untreated DC (Fig. 4). Thus, the DF272-defined structure on DC appears to transmit inhibitory signals to T cells, which can be blocked with mAb DF272.
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It is well established that IL-10-treated DC are not only poor stimulators of T cells but are capable of inducing Ag-specific anergy in T cells (5, 16, 18). This anergic state cannot be overcome when T cells are restimulated with untreated DC. To test whether blocking of the DF272-defined molecule on DC might enable these cells to break this hypoproliferative state, allogeneic T cells were stimulated first with either IL-10-treated DC or untreated DC and subsequently restimulated with untreated DC from the same donor as used in the primary response. We observed that T cells stimulated in the primary response with IL-10-treated DC showed a reduced proliferative response (Fig. 5a) compared with restimulation of T cells primed with untreated DC (Fig. 5b). This hypoproliferative response was reversible by adding exogenous IL-2 (data not shown). Importantly, addition of mAb DF272 to DC in the secondary response also resulted in reconstitution of T cell proliferation of the anergized T cells (Fig. 5a). This effect was not observed with the control mAb M80. Taken together, these results indicate that the DF272-defined molecule on DC is involved in the induction and maintenance of anergy in T cells by IL-10-treated DC.
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The profound effects of mAb DF272 binding to DC on T cell proliferation raised the question of whether the DF272-defined molecule might also be involved in regulating cytokine production in T cells. To analyze this possibility, we cocultured T cells with allogeneic DC treated with mAb DF272.
We observed that T cells stimulated with mAb DF272-treated DC released significantly more IL-2 and IFN- than those stimulated with untreated DC (Fig. 6). In contrast, production of IL-4 and IL-10 was reduced (-41 ± 26% and -46 ± 22%, respectively) upon activation with DC pretreated with mAb DF272. Thus, the DF272-defined Ag on DC appears to deliver signals to T cells that favor IL-10 and IL-4 production. Blocking this signal with mAb DF272 induces a type-1 cytokine release pattern.
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To identify the molecule recognized by the mAb DF272, we used a retroviral expression cloning approach (10, 11). A cDNA library from monocyte-derived DCs had been constructed in the retroviral vector CRU5-IRES-GFP featuring CMV promoter driven expression of the cDNA along with GFP expression from an internal ribosomal entry site. The vector was packaged by Phoenix cells into ecotropic virus particles that were then used to infect target cells. From the transduced cells, those expressing the respective receptor structure recognized by mAb DF272 were isolated by MACS and used for RNA preparation. RNA was reversibly transcribed, and the retrovirus-encoded cDNA insert was PCR amplified. The PCR product was cloned into the mammalian expression vector His-TOPO. To prove the specificity of the inserted cDNA coding for Ag, the plasmids were transfected into 293T cells and stained for mAb DF272 reactivity (Fig. 7A). The cDNA leading to the expression of the molecule recognized by mAb DF272 was sequenced and revealed a length of 1564 bp with an open reading frame of 972 bp. A BLAST similarity search at the National Center for Biotechnology Information showed 100% identity to B7-H1 (PD-L1) (12). Results presented in Fig. 7B demonstrate that mAb DF272 specifically reacts with B7-H1+ transductants, but not with CD80+ transductants.
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With mAb DF272 we then investigated B7-H1 protein expression in peripheral tissues including human tonsil, lymph node, thymus, spleen, colon, skin, lung, placenta, heart, and skeletal muscle. Results presented in Fig. 8A demonstrate that B7-H1 was strongly expressed on various human epithelia. For instance, squamous epithelia from human tonsil, cylindric epithelium from the colon, cells from the basal layers of squamous epithelium in the skin, and Hassall’s bodies in the thymus were recognized by mAb DF272 as well as bronchial epithelial and globet cells from lung sections (data not shown). No such reactivity was found in stainings with the isotope-matched, control mAb VIAP (Fig. 8A). mAb DF272 also reacted with syncytiotrophoblasts from human placenta and some keratinocytes in human skin (data not shown). Interestingly, strong B7-H1 expression was observed in a perinuclear dot-like pattern in heart and skeletal muscle cells, suggesting intracellular localization.
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Discussion |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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We conclude these functional characteristics of B7-H1 on the basis of our results with intact IgG as well as with univalent Fab of mAb DF272. With both preparations, blocking of B7-H1 on DC was found to enhance T cell stimulation by immature DC and was capable of reverting the poor stimulatory capacity of IL-10-treated DC. Originally, B7-H1 was identified as a costimulatory receptor structure promoting T cell proliferation (12). This costimulatory effect was detectable with B7-H1-transfected COS cells as well as with immobilized B7-H1 fusion proteins combined with suboptimal doses of anti-TCR Abs. In contrast, Freeman et al. (13) demonstrated an immunoinhibitory function for B7-H1. In their experiments, immobilized B7-H1 fusion proteins inhibited T cell proliferation induced by CD3 mAbs. Moreover, Dong et al. (24) reported an apoptosis-inducing property of B7-H1 on tumor cells for cytotoxic T cells. Thus, similar "professional APC-free" T cell activation protocols led to opposite results that are still a matter of debate (25). However, our findings presented in this study clearly revealed that B7-H1 functions as an inhibitory receptor structure on DC.
We believe that the postulated inhibitory signals from B7-H1 are counterbalanced in their activity by the plethora of additional coreceptors expressed on DC. We have shown for instance that B7-H1 is strongly up-regulated on mature DC. Nevertheless, mature DC are the most potent T cell stimulators known (6, 26), and blocking of B7-H1 with mAb DF272 had little effect on them. Because mature DC express high levels of MHC molecules or signal 1 and also abundantly express costimulatory molecules such as B7.1 (CD80), B7.2 (CD86), or signal 2, it seems that B7-H1-derived inhibitory signals are overruled under such conditions and become detectable only when signals 1 and/or 2 are low. This is the case with IL-10-treated DC, which are poor stimulators of T cells (5, 16, 18). The blocking of B7-H1 on these APC reconstitutes the T cell stimulatory quality of DC, indicating that B7-H1 signals are more critical in this case. Thus, we hypothesize that B7-H1 plays a more important role when signals 1 and/or 2 are moderate on APC. This idea is supported by the observation that CD28 cosignaling prevents the inhibitory role of B7-H1 fusion proteins at suboptimal doses of CD3 mAbs or by the finding that inhibitory B7-H1 effects were not found in the presence of large amounts of CD3 mAbs (13). Thus, negative signals from B7-H1 seem to set a threshold for T cell activation on a fully immunocompetent DC.
Yet, B7-H1 may not only become critical in the case of immunocompromised DC but seems to play an important role in controlling anergized T cells through DC. We observed that T cells that were anergized by stimulation with IL-10-treated DC started to proliferate again when they were restimulated with DC treated with mAb DF272. This finding suggests that B7-H1-derived signals might promote the maintenance of an established anergic state in T cells. This could be explained by increased expression of PD-1 or additional, so far undefined, ligands of B7-H1 on activated T cells (13, 24, 27, 28), rendering previously activated T cells more susceptible to B7-H1 effects than resting T cells (29).
The underlying mechanisms for the profound effects on T cell proliferation induced by blocking B7-H1 on DC are not yet understood. Modulation of the cytokine production pattern in T cells through B7-H1 might certainly be involved. For instance, we observed that the blocking of B7-H1 on DC with mAb DF272 reduced the amount of IL-10 and IL-4 released by cocultured T cells. In contrast, IFN- and IL-2 production was strongly increased under these conditions. These results suggest that B7-H1 cosignaling of DC might not only increase IL-10 production (12, 14), but reveal a more T cell-directive function. B7-H1 seems to promote type-2 T cell responses and alternatively regulates the expression of critical factors for T cell proliferation, IL-2 and IL-10. The finding that B7-H1 signaling might enhance IL-10 production, but inhibit IL-2 production, could explain how B7-H1 controls T cell anergy. However, it remains to be determined whether this effect is directly transferred from the DC to the Ag-specific T cell or indirectly, i.e., via activation of regulatory T cells through B7-H1.
Interestingly, the observed immunoregulatory potency of B7-H1 may not only be mediated via DC but may also be exploited by nonimmune cells. Expression of B7-H1 in extracts of nonhemopoietic tissues has been detected at the RNA level (12, 13, 14, 25, 29). We could confirm these findings and demonstrate that several tissues express B7-H1. Of particular interest in this respect is that epithelial cells as well as muscle cells were found to strongly express B7-H1 protein. Because these nonimmune cells are not usually equipped with costimulatory molecules like CD80 or CD86 (25), it is thus tempting to speculate that B7-H1 on such cells may have profound inhibitory effects on adjacent T cells. This could also play a role in the induction and maintenance of anergy in peripheral T cells.
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Acknowledgments |
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Footnotes |
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2 Address correspondence and reprint requests to Dr. Johannes Stöckl, Institute of Immunology, University of Vienna, Borschkegasse 8a, A-1090 Vienna, Austria. E-mail address: johannes.stoeckl{at}univie.ac.at
3 Abbreviations used in this paper: DC, dendritic cell; PI, propidium iodide; GFP, green fluorescence protein; PD-L1, programmed death-1 ligand.
Received for publication May 20, 2002. Accepted for publication January 2, 2003.
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A. S. Krupnick, A. E. Gelman, W. Barchet, S. Richardson, F. H. Kreisel, L. A. Turka, M. Colonna, G. A. Patterson, and D. Kreisel Cutting Edge: Murine Vascular Endothelium Activates and Induces the Generation of Allogeneic CD4+25+Foxp3+ Regulatory T Cells J. Immunol., November 15, 2005; 175(10): 6265 - 6270. [Abstract] [Full Text] [PDF]
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P. H. Tan, J. B. Yates, S.-A. Xue, C. Chan, W. J. Jordan, J. E. Harper, M. P. Watson, R. Dong, M. A. Ritter, R. I. Lechler, et al. Creation of tolerogenic human dendritic cells via intracellular CTLA4: a novel strategy with potential in clinical immunosuppression Blood, November 1, 2005; 106(9): 2936 - 2943. [Abstract] [Full Text] [PDF]
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S. Kirchberger, O. Majdic, P. Steinberger, S. Bluml, K. Pfistershammer, G. Zlabinger, L. Deszcz, E. Kuechler, W. Knapp, and J. Stockl Human Rhinoviruses Inhibit the Accessory Function of Dendritic Cells by Inducing Sialoadhesin and B7-H1 Expression J. Immunol., July 15, 2005; 175(2): 1145 - 1152. [Abstract] [Full Text] [PDF]
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S. Bluml, S. Kirchberger, V. N. Bochkov, G. Kronke, K. Stuhlmeier, O. Majdic, G. J. Zlabinger, W. Knapp, B. R. Binder, J. Stockl, et al. Oxidized Phospholipids Negatively Regulate Dendritic Cell Maturation Induced by TLRs and CD40 J. Immunol., July 1, 2005; 175(1): 501 - 508. [Abstract] [Full Text] [PDF]
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P. H. Tan, P. Sagoo, C. Chan, J. B. Yates, J. Campbell, S. C. Beutelspacher, B. M. J. Foxwell, G. Lombardi, and A. J. T. George Inhibition of NF-{kappa}B and Oxidative Pathways in Human Dendritic Cells by Antioxidative Vitamins Generates Regulatory T Cells J. Immunol., June 15, 2005; 174(12): 7633 - 7644. [Abstract] [Full Text] [PDF]
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T. Ito, T. Ueno, M. R. Clarkson, X. Yuan, M. M. Jurewicz, H. Yagita, M. Azuma, A. H. Sharpe, H. Auchincloss Jr, M. H. Sayegh, et al. Analysis of the Role of Negative T Cell Costimulatory Pathways in CD4 and CD8 T Cell-Mediated Alloimmune Responses In Vivo J. Immunol., June 1, 2005; 174(11): 6648 - 6656. [Abstract] [Full Text] [PDF]
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A. Saudemont, N. Jouy, D. Hetuin, and B. Quesnel NK cells that are activated by CXCL10 can kill dormant tumor cells that resist CTL-mediated lysis and can express B7-H1 that stimulates T cells Blood, March 15, 2005; 105(6): 2428 - 2435. [Abstract] [Full Text] [PDF]
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S. Hirata, S. Senju, H. Matsuyoshi, D. Fukuma, Y. Uemura, and Y. Nishimura Prevention of Experimental Autoimmune Encephalomyelitis by Transfer of Embryonic Stem Cell-Derived Dendritic Cells Expressing Myelin Oligodendrocyte Glycoprotein Peptide along with TRAIL or Programmed Death-1 Ligand J. Immunol., February 15, 2005; 174(4): 1888 - 1897. [Abstract] [Full Text] [PDF]
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A. De Creus, M. Abe, A. H. Lau, H. Hackstein, G. Raimondi, and A. W. Thomson Low TLR4 Expression by Liver Dendritic Cells Correlates with Reduced Capacity to Activate Allogeneic T Cells in Response to Endotoxin J. Immunol., February 15, 2005; 174(4): 2037 - 2045. [Abstract] [Full Text] [PDF]
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K. Pfistershammer, O. Majdic, J. Stockl, G. Zlabinger, S. Kirchberger, P. Steinberger, and W. Knapp CD63 as an Activation-Linked T Cell Costimulatory Element J. Immunol., November 15, 2004; 173(10): 6000 - 6008. [Abstract] [Full Text] [PDF]
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P. Smith, C. M. Walsh, N. E. Mangan, R. E. Fallon, J. R. Sayers, A. N. J. McKenzie, and P. G. Fallon Schistosoma mansoni Worms Induce Anergy of T Cells via Selective Up-Regulation of Programmed Death Ligand 1 on Macrophages J. Immunol., July 15, 2004; 173(2): 1240 - 1248. [Abstract] [Full Text] [PDF]
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P. Steinberger, O. Majdic, S. V. Derdak, K. Pfistershammer, S. Kirchberger, C. Klauser, G. Zlabinger, W. F. Pickl, J. Stockl, and W. Knapp Molecular Characterization of Human 4Ig-B7-H3, a Member of the B7 Family with Four Ig-Like Domains J. Immunol., February 15, 2004; 172(4): 2352 - 2359. [Abstract] [Full Text] [PDF]
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S. Wintterle, B. Schreiner, M. Mitsdoerffer, D. Schneider, L. Chen, R. Meyermann, M. Weller, and H. Wiendl Expression of the B7-Related Molecule B7-H1 by Glioma Cells: A Potential Mechanism of Immune Paralysis Cancer Res., November 1, 2003; 63(21): 7462 - 7467. [Abstract] [Full Text] [PDF]
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) of the mAb DF272. Proliferation of T cells was monitored on day 5 of culture by adding [methyl-3H]TdR followed by measuring [methyl-3H]TdR incorporation 18 h later. The figure shows mean values ± SD of three experiments.
) or Fab of DF272 (
). The figure shows the results of one representative experiment of three independent experiments.
), an isotype-matched control mAb (M80, 
