Clonal expansion of mycobacterial heat‐shock protein–reactive T lymphocytes in the synovial fluid and blood of rheumatoid arthritis patients

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Abstract
Objective. To examine the reactivity pattern and T cell receptor (TCR) characteristics of mycobacterial heat‐shock protein 65 (hsp65)‐reactive T cells generated from paired synovial fluid (SF) and peripheral blood (PB) samples obtained from rheumatoid arthritis (RA) patients and from healthy subjects. Methods. The reactivity pattern of hsp65‐reactive T cell clones generated under limiting‐dilution conditions was analyzed in 3H‐thymidine incorporation assays. The TCR variable regions of these hsp65‐reactive T cells were characterized by polymerase chain reaction with TCR AV‐ and BV‐specific primers and by DNA sequence analysis of the third complementarity‐determining region (CDR3). Results. The hsp65‐reactive T cells derived both from RA patients and controls preferentially recognized the 1–170 and 303–540 regions of hsp65 and did not cross‐react with human hsp60. The hsp65‐reactive T cell clones derived from RA patients displayed a restricted TCR AV and BV gene usage, which can be attributed to the limited clonal origin(s) of the independent T cell clones, as evidenced by CDR3 sequence analysis. These clonally expanded T cells were found in both PB and SF and in different inflamed joints of RA patients. Conclusion. Our study suggests that there is in vivo clonal activation and expansion of mycobacterial hsp65‐reactive T cells in patients with RA.