T cell responses to a human cartilage autoantigen in the context of rheumatoid arthritis-associated and nonassociated HLA-DR4 alleles.
OBJECTIVE: To analyze the CD4+ T cell responses to the human cartilage antigen glycoprotein-39 (HCgp-39) in the context of rheumatoid arthritis (RA)-associated (DRalphabeta1*0401) and nonassociated (DRalphabeta1*0402) HLA class II molecules. METHODS: Large numbers of HCgp-39-specific T cell hybridomas were generated following immunization of HLA-DR4/human CD4 transgenic, murine major histocompatibility complex class II deficient mice with native HCgp-39. Fine epitope mapping of DRalphabeta1*0401-and DRalphabeta1*0402-restricted T cell hybridomas was performed using overlapping synthetic peptides. Antigen-specific cytokine production by lymph node T cells was evaluated after immunization with native antigen. Proliferative T cell responses of healthy human subjects were compared with the T cell responses of patients with active RA using HCgp-39 epitopes defined in HLA-DR4 transgenic mice. RESULTS: CD4+ T cells from DRalphabeta1*0401 and DRalphabeta1*0402 transgenic mice identified completely different immunodominant peptide epitopes of HCgp-39, and this was not explained by known DR4-binding motifs or direct peptide-binding studies. DRalphabeta1*0401-restricted, antigen-specific T cells produced significantly more interferon-gamma and tumor necrosis factor a in response to HCgp-39 than did T cells from DRalphabeta1*0402 transgenic mice. Finally, HCgp-39 peptides defined in DRalphabeta1*0401 transgenic mice stimulated T cells from HLA-DR4 positive human subjects and RA patients, but not T cells from HLA-DR4 negative individuals. CONCLUSION: T cell epitopes of HCgp-39 that were defined in HLA-DR4 transgenic mice stimulated T cells from human subjects carrying RA-associated HLA-DR4 alleles. HLA-DR4 molecules may influence the disease process in RA both by presentation of selected peptide epitopes and by promoting the production of proinflammatory cytokines in synovial joints.[1]References
- T cell responses to a human cartilage autoantigen in the context of rheumatoid arthritis-associated and nonassociated HLA-DR4 alleles. Cope, A.P., Patel, S.D., Hall, F., Congia, M., Hubers, H.A., Verheijden, G.F., Boots, A.M., Menon, R., Trucco, M., Rijnders, A.W., Sønderstrup, G. Arthritis Rheum. (1999) [Pubmed]
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