Effects of insulin on phytohemagglutinin-P, concanavalin-A, and pokeweed mitogen in diabetic and nondiabetic lymphocytes

Blast transformation of lymphocytes from diabetics and nondiabetics was evaluated after adding insulin at various concentrations. Responses to phytohemagglutinin-P (PHA-P), concanavalin-A (CON-A) and pokeweed mitogen (PWM) were measured in the presence of exogenous insulin added in physiologic increments of 0, 10, 20, 30, and 40 microunits of activity per ml of culture medium. A modified method utilizing heparinized whole blood was used. After a four day incubation period, 3H-TdR uptake was evaluated and used as the index of stimulation. A standard pooled z test for comparison of 3H-TdR uptake showed a decrease in blast transformation of diabetic lymphocytes compared to nondiabetic lymphocytes to the mitogens PHA-P (p less than 0.01), CON-A (p less than 0.01), and PWM (p less than 0.01). Added insulin increased the diabetic lymphocyte blast transformation response to each of the mitogens. Blast transformation in diabetics never reached the leve of blast transformation in nondiabetics. It is hypothesized that there is a cellular defect in either membrane receptors or intracellular metabolic pathways which accounts for the decrease in diabetic lymphocyte blast transformation.