EFFECT OF SERINE THREONINE KINASE INHIBITORS ON MOTILITY OF HUMAN-LYMPHOCYTES AND U937 CELLS/

Mononuclear cell migration across the endothelium and through connecti ve tissue into inflammatory sites is a multi-step process. After adhes ion to the endothelium, there is an initial change in shape from spher ical to irregular, followed by the migratory phase itself in which the cells constantly change in shape. In this paper we have investigated the possibility that the shape-changing in this latter phase is contro lled by serine/threonine phosphorylation. For this purpose, we used a spontaneously shape-changing variant of U937 monocytoid cells as well as human peripheral blood lymphocytes that had been previously activat ed by anti-CD3. To test the role of phosphorylation in shape-changing, a wide range of serine/threonine kinase inhibitors was tested, includ ing ML-7, KT5720, KT5823, H7, H8, staurosporine, calphostin C, sphingo sine, bisindolylmaleimide, chelerythrine and KN-62. Only those compoun ds which inhibited protein kinase C prevented lymphocyte and U937 shap e-change and transmigration across polycarbonate filters. However, one specific protein kinase C inhibitor, bisindolylmaleimide, stimulated lymphocyte shape-change. In conclusion, these studies show that activa tion of a serine/threonine kinase is necessary for the constant shape- changing required for motility of mononuclear cells. The kinase may be a protein kinase C isotype or a closely related enzyme.