Juvenile rheumatoid arthritis patients manifest immune reactivity to the mycobacterial 65-kDa heat shock protein, to its 180-188 peptide, and to a partially homologous peptide of the proteoglycan link protein.

Immune reactivity to the 65-kDa mycobacterial heat shock protein (hsp65) has been associated with arthritis in rats and humans. In this report we evaluated patients with juvenile rheumatoid arthritis for such immunity. A high proportion of affected children showed both antibody and T lymphocyte responses to hsp65 and to two related peptides: the nonapeptide 180-188 sequence of hsp65 and a partially homologous peptide of the cartilage proteoglycan link protein. The titer of circulating antibodies was generally higher in patients with clinically active disease. In contrast to the juvenile rheumatoid arthritis patients, patients with adult rheumatoid arthritis tended to have lower responses of their peripheral blood T lymphocytes to the whole hsp65 molecule. Moreover, the adult rheumatoid arthritis patients did not respond to the peptides. Thus, there appear to be immunological differences between juvenile and adult forms of rheumatoid arthritis related to hsp65 reactivity.