Abnormal T-lymphocyte subsets in type I diabetes

Type I (insulin-dependent) diabetes mellitus is a slow autoimmune disease associated with the selective destruction of beta-cells in the islets of Langerhans. Recent studies in humans indicate that autoantibodies to insulin and islets of Langerhans appear years before overt diabetes and identify a normoglycemic prediabetic state. To determine whether type I diabetes mellitus represents a generalized immunologic disorder, we studied the phenotypic characteristics of peripheral blood lymphocytes from all stages, i.e., prediabetic, new-onset diabetic, and long-term diabetic patients, with the anti-2H4 monoclonal antibody CD45R, which defines a human suppressor-inducer subset, and the anti-4B4 monoclonal antibody CDw29, which defines a human helper-inducer subset of peripheral blood lymphocytes. All 22 prediabetic patients had elevated T4+2H4+ (suppressor-inducer) cells and reciprocal depressed T4+4B4+ (helper-inducer) cells compared with healthy age-matched control subjects. In addition, the T4/T8 ratio in prediabetic patients was decreased compared with the age-matched control subjects. The abnormal T4+2H4+ and T4+4B4+ subsets were resolved in 20 new-onset and 15 long-term diabetic patients. Family studies showed that the changes in the 2H4 and 4B4 antigens were not part of an inherited polymorphic determinant, because these markers were normal in unaffected siblings and parents. Ten prediabetic patients were restudied greater than 1 yr after the original analysis and showed the persistence of the observed changes. This abnormal increase in suppressor-inducer cells and decrease in helper-inducer cells among islet and insulin antibody-positive prediabetic patients may be of help in understanding diabetes pathogenesis and may also be an early noninvasive screening tool for the detection of the prediabetic state.