Insulin modulates human mononuclear adherent cell fibrinolytic and phagocytic activities

The effects of physiological concentrations of insulin on the fibrinolytic activity of peripheral blood leucocytes were investigated. Significant enhancement of the fibrinolytic activity of mononuclear adherent cells was observed, whereas lymphocytes and granulocytes were unaffected. Furthermore, insulin stimulated mononuclear adherent cells to phagocytize inert particles but not to secrete lysozyme. It is suggested that these results are attributable to the large number of insulin receptors present on the monocyte membrane, and that the regulatory mechanism of fibrinolysis and phagocytosis differs from that controlling the secretion of lysozyme.