ANTIBODIES TO HUMAN HSP60 IN PATIENTS WITH JUVENILE CHRONIC ARTHRITIS, DIABETES-MELLITUS, AND CYSTIC-FIBROSIS

The 60-kD heat shock protein (hsp60) has been implicated in the etiolo gy and pathogenesis of both experimental and naturally occurring autoi mmune diseases such as juvenile chronic arthritis (JCA). Human hsp60 i s expressed in inflamed synovial tissue, and T lymphocytes both from p eripheral blood and synovial fluid show reactivity to human hsp60. Bec ause the anti-hsp60 B lymphocyte response has been less well studied, we have determined the occurrence of IgG anti-human hsp60 antibodies i n patients with JCA and various other autoimmune diseases of childhood . Serum IgG anti-human hsp60 antibodies in JCA patients were significa ntly higher compared with control children (358 and 163 U/mL, respecti vely). Within the group of JCA patients, the highest antibody titers w ere found in the subgroup with a polyarticular onset of JCA. IgG anti- human hsp60 antibody levels in synovial fluid were 3- to 4-fold higher compared with paired serum samples. Because this difference was not f ound for total IgG or for irrelevant antibodies (anti-polyribosylribit ol phosphate), this suggests local anti-hsp60 antibody production in t he synovial compartment. The occurrence of anti-hsp60 antibodies is no t specific for JCA but also is found in children with systemic lupus e rythematosus and in cystic fibrosis, whereas mixed connective tissue d isease and insulin-dependent diabetes are negative in this respect. Wh ether the anti-human hsp60 antibodies are directed toward species-spec ific sequences or to conserved sequences of the hsp60 molecule remains to be determined.