Mycobacteria and human heat shock protein—specific cytotoxic t lymphocytes in rheumatoid synovial inflammation

Objective. To study the cytotoxic capacity of mycobacteria‐specific T lymphocyte lines and clones from sites of inflammation in patients with rheumatoid arthritis (RA). We also studied antigen specificity, surface phenotype, expression of T cell receptors (TCR), and HLA restriction. Methods. Autologous macrophages (Mπ) from the synovial membrane (SM), synovial fluid (SF), or peripheral blood (PB) were used as target cells in cytotoxicity assays. Results. All SM and SF cell lines tested thus far have shown specific lysis of the autologous Mπ from SM or PB that had been pulsed with BCG (bacillus Calmette‐Guerin), but no cytotoxicity when the targets were pulsed with irrelevant antigens such as tetanus toxoid and Chlamydia. Both CD4+ and CD8+ cells were shown to be involved in the specific cytolysis. The majority of the cytotoxic T lymphocyte (CTL) lines were TCRα/β+ cells. However, both TCRα/β+ and TCRγ/δ+ clones (TCR δ1+) from one RA patient showed antigen‐specific lysis. Antigen‐specific recognition by a number of CTL lines and clones generated from SF and SM was restricted by HLA—DR molecules. Two Mycobacterium bovis 65‐kd heat shock protein (HSP)–specific TCRα/β+ SF T cell clones also lysed Mπ that had been pulsed with a recombinant human 65‐kd HSP. Conclusion. Joint inflammation and destruction might be partly attributable to a cross‐reaction of mycobacteria‐induced cytotoxic T cells with self HSP.