Insulin-like growth factor-1 increases the mitogenic response of human peripheral blood lymphocytes to phytohemagglutinin

Abstract Receptors for insulin and insulin-like growth factor-1 (IGF-1) have been demonstrated on activated T-lymphocytes. The question is whether receptors for insulin or IGF-1 have any function in these cells. In this study we demonstrate that the concentration of IGF-1 in commercial samples of fetal calf serum is about 70 times that of insuli. Moreover, antibodies of IGF-1 reduce responses of human peripheral blood mononuclear cells to PHA by about 50% whereas antibodies to insulin have no demonstrable effect. These observations suggest that binding of IGF-1 to specific receptors contributes to the proliferative responses of activated T-lymphocytes.