Different percentages of CD8+ lymphocytes in long-term type 1 diabetics with and without residual beta cell function

About 15% of Type 1 diabetics display residual beta cell function after more than 10 yr duration of diabetes, indicating that the disease mechanisms have stopped before all beta cells are destroyed. Peripheral blood lymphocytes were studied from such patients, 11 females and 12 males, 29 +/- 1 yr old, who had had diabetes for 14 +/- 1 yr. A completely matched group of 23 Type 1 diabetics with the same disease duration, but without residual beta cells, were also studied together with a healthy control group. Lymphocytes were marked with monoclonal OKT antibodies and examined by flow cytometry (FACS). There was no difference between the three groups in the absolute number of lymphocytes and helper T-cells (CD4+:40.2 +/- 1.3 vs. 40.4 +/- 1.3 vs. 41.1 +/- 1.8%). In respect of CD8+ (suppressor/cytotoxic) T-cells, the diabetics without beta cells showed 25.9 +/- 1.0%, significantly less than both the patients with preserved beta cell function (29.0 +/- 0.9%, p less than 0.02) and the controls (29.5 +/- 1.3%, p less than 0.02). CD3+ (pan) T-cells showed parallel changes (67.8 +/- 1.5 vs. 71.0 +/- 1.4 vs. 72.2 +/- 1.4%, p less than 0.05). The metabolic state was similar in the two patient groups, and there was no correlation between metabolic and immunological parameters. It is unknown whether the normalization of the T-cell subpopulation, especially the CD8+ lymphocytes, in patients with residual beta cell function at a point when the disease process is apparently at rest, is of causal significance, or of only marker significance.