Depressed proliferative responses by peripheral blood mononuclear cells from early arthritis patients to mycobacterial heat shock protein 60

Objectives. T-cell responses to mycobacterial heat shock protein 60 (M.hsp6 0) have been implicated in the pathogenesis of adjuvant arthritis, but whet her they play a role in rheumatoid arthritis (RA) is undefined. We therefor e examined T-cell responses to M.hsp60 and to other recall antigens in a co hort of patients with early RA and in healthy controls. Methods. In vitro peripheral blood mononuclear cells' (PBMC) proliferative responses to antigen were measured by [H-3]thymidine incorporation, and res ults correlated with clinical and laboratory features of disease. Results. Whereas responses to the recall antigens tetanus toxin and purifie d protein derivative (PPD) were equivalent in the two groups, responses to both M.hsp60 and the Escherichia coli hsp60 were lower in the RA patients. These results could not be explained by either the higher prevalence of HLA -DR4 in the RA group, or the disease severity of the patients. Conclusion. In the light of results from the adjuvant arthritis model which suggest that arthritis may be ameliorated by the actions of an hsp60-react ive T-cell population, the lack of response to M.hsp60 in RA could contribu te to disease persistence.