[The action of insulin on human lymphocytes stimulated with mitogens "in vitro". I. Study on normal subjects]

Insulin at 25, 50, 250, 500 and 1000 mcU/ml concentration added to lymphocyte cultures under PHA stimulation increases [3H] Thymidine incorporation. Maximum effect is obtained at 50 mcg/ml of PHA and 250 mcU/ml of insulin after 96 hours of incubation. Insulin stimulates cultures when it is added between the 12th and the 24th hour. Cultures stimulated wih high dose (250 mcg/ml) of PHA do not show any increase in mitosis. Ours and other Authors results seem to show that the mechanism of action of insulin works through specific receptors on lymphocytes. These receptors appear some hours after mitogen stimulation; our results showing maximum effect when insulin is added after 12-24 hours support this hypothesis.