Antibodies to heat shock protein 65 kD in type 1 diabetes mellitus

To determine whether antibodies to mycobacterial heat shock protein of 65 kD molecular weight (hsp 65) could be important in the pathogenesis of Type 1 diabetes we tested patients before and at diagnosis of diabetes, as well as patients with rheumatoid arthritis. Using ELISA, increased hsp 65 antibodies were detected in 2 of 8 pre-diabetic twins, 1 of 13 newly diagnosed untreated diabetic patients and 3 of 10 rheumatoid arthritis patients. Levels of hsp 65 antibodies in pre-diabetic twins, median (range), 0.25 (0.104-1.904) and newly diagnosed diabetic patients (mean +/- SD) (0.299 +/- 0.220), did not differ significantly either from each other or from their control subjects (0.134 +/- 0.123). In contrast, levels of hsp 65 antibodies in rheumatoid patients (0.59 +/- 0.42) were significantly higher than in their control subjects (0.21 +/- 0.18; p = 0.02). Of twins studied prospectively before diagnosis, at diagnosis but before insulin treatment, and soon after diagnosis, three of four had hsp 65 antibodies at some stage. We conclude that serological immunity to mycobacterial hsp 65 can occur in Type 1 diabetes, but it is neither a characteristic nor a specific feature of the disease.