Abnormalities of CD4+ T lymphocyte proliferative responses from patients with recently diagnosed insulin-dependent diabetes mellitus.

To investigate the abnormalities of cell-mediated immunity in patients with recently diagnosed insulin-dependent diabetes mellitus (IDDM), we studied the responses of the two major T lymphocyte subsets from peripheral blood lymphocytes (PBL) to mitogen stimulation. Samples for PBL were obtained from a group of IDDM patients and from a group of normal controls. CD4+ and CD8+ T cells were isolated and were subsequently stimulated with three specific lymphocyte mitogens, namely Phytohemagglutinin (PHA), Concanavalin A (Con A) and Pokeweek mitogen (PWM). The proliferative response was measured by incorporation of radioactive thymidine in lymphocyte cultures which were stimulated by the three mitogens. The responses of CD8+ T cells from IDDM patients and from controls were not significantly different. However, CD4+ T cells from IDDM patients showed significantly depressed responses to PHA and Con A and to a much lesser extent to PWM. These data provide new information regarding the CD4+ T lymphocyte abnormalities found in patients with IDDM.