Synovial fluid T cell reactivity against 65 kD heat shock protein of mycobacteria in early chronic arthritis.

The in vitro proliferative response against a recombinant 65 kD Mycobacterium bovis protein that has 100% homology with the 65 kD protein of M tuberculosis was tested in synovial fluid and peripheral blood mononuclear cells from patients with rheumatoid arthritis (RA) and other types of chronic arthritis. An acetone precipitate (AP) of M tuberculosis, and a purified protein derivative (PPD) of M tuberculosis were also tested. Responsiveness of synovial fluid lymphocytes to the mycobacterial antigens was found both in patients with RA and in patients with other forms of chronic inflammatory arthritis, but not among controls. T cell reactivity against mycobacterial antigens was nearly always higher in synovial fluid than in peripheral blood in those patients who showed reactivity. A significant association was found between responsiveness of synovial T cells to the 65 kD protein and AP, but no relation between responsiveness to the 65 kD protein and PPD. Both the number of 65 kD protein responders and the mean proliferative response of synovial T cells to the 65 kD protein were inversely correlated with duration of joint inflammation. Thus, a 65 kD-protein-specific reactivity of synovial T cells, mainly present in an early stage of joint inflammation, may be responsible for triggering chronic arthritis.