Reactivity of t cells from patients with rheumatoid arthritis towards human and mycobacterial HSP60

Recently, Mycobacterium tuberculosis (Mb) hspoO specific T cells which can protect against arthritis have been isolated. Interestingly, these cells responded to an epitope, homologous to rat (self) hspoO. The suggestion that T cell reactivity towards self hspoO can protect against arthritis is supported by the fact that juvenile chronic arthritis patients with T cell reactivity to human hspoO have a favourable course of disease. Protection by self hspoO specific T cells may be based on suppressive T2 cell activity, an activity which may also play a role in rheumatoid arthritis (RA). The responses against Mb and human hsp60 in RA are unclear in terms of disease stimulation or suppression. In the present study we analyzed reactivity of T cells from RA patients to Mb and human hspoO, especially with respect to Tl and T2 activities. High antigen reactivity against human and Mb hspoO was found for synovial fluid T cells of RA patients. Human hspoO specific T cell lines produced significantly more IL-4 and less IFNg than Mb hspoO specific T cell lines. Moreover, IL-4 increased proliferation of T cells, stimulated with human hspoO, whereas it decreased Mb hsp60 induced proliferation. The difference in T1/T2 activity and in IL-4 altered growth responses, of Mb and human hspoO specific T cells suggest that these cells differ in function. Assuming Tl cell activity to be pathogenic in RA, our results suggest a role for self hsp60 specific T cells in protection or suppression of the disease.