MHC-CLASS-I ANTIGEN EXPRESSION IN PATIENTS WITH IDDM AND THEIR SIBLINGS

MHC class I antigen expression was found to be low on the lymphocytes of patients with insulin dependent diabetes mellitus (IDDM). Thus, it has been proposed that the defective expression of MHC antigens could lead to faulty immunological responses with the eventual destruction o f the pancreatic beta cells, The objective in this study was to compar e MHC antigen expression in IDDM patients and their presently healthy siblings. Nineteen children (mean age 10.8 +/- 3.9 years) with diabete s and their 25 siblings (mean age 10.7 +/- 4.6 years) were enrolled in the study, Peripheral blood lymphocytes isolated from venous blood sa mples were incubated with FITC conjugated monoclonal antibody W6/32, T he amount of antibody binding by cell surface MHC class I antigens was assessed by flow cytometry. MHC class I molecule expression did not d iffer significantly among IDDM patients and their siblings, It was con cluded that MHC class I antigen expression did not appear to be indica tive of a susceptibility to develop autoimmune diabetes.