Lymphocyte subsets and immune complexes in long-standing diabetic patients: relation with the presence of microangiopathy.

Subsets of peripheral T lymphocytes by monoclonal antibodies and circulating immune complexes by two different methods were evaluated in 36 long-standing diabetic patients, 19 Type 1 (insulin dependent) and 17 Type 2 (non-insulin dependent). In all patients the presence of microangiopathy was assessed by retinal fluoroangiography, albuminuria and creatinine clearance. In patients with Type 1 diabetes a significant decrease of total T and of T cells with helper phenotype (T4), together with an increase of T cells with suppressor/cytotoxic phenotype (T8), were observed. No significant modifications in the percentage of T lymphocyte subsets were detected in patients with Type 2 diabetes. Immune complexes were found to be significantly increased in Type 1 compared with Type 2 diabetic patients. Patients with very high levels of T8+ cells did not have detectable immune complexes and had no evidence of microangiopathy. By contrast, patients with normal levels of these cells were found to have raised immune complexes and showed retinopathy of varying degree. The results of this study indicate that: (1) a relationship exists between cells with T8 phenotype, some immune complexes and the presence of microangiopathy; (2) the decrease of T4+ cells in Type 1 diabetics with long duration of disease may be responsible for the known susceptibility to infections in these patients.