Phorbol myristate acetate induction of chemotactic migration of human polymorphonuclear neutrophils.

The in vitro migration of human polymorphonuclear neutrophils (PMNs) was studied employing an enzymatic assay of cell migration with phorbol myristate acetate (PMA) as the test stimulant. Our data clearly show that PMA in concentrations between 1 and 100 ng/ml in the lower wells of blind-well chambers induced chemotactic migration. Chemokinesis (increased migration) was not induced when PMA was present in both the upper and lower chambers (i.e., in a nongradient mode). Clearly our data indicate that PMA is chemotactic for human PMNs and, coupled with published studies of the effect of PMA on PMNs, suggest activation of an intracellular gradient of membrane-associated protein kinase C as a possible new mechanism for the induction of oriented migration of PMNs. Such a mechanism may be generalized to include membrane-soluble materials (e.g., inflammatory mediators, microbial products), which establish internal gradients of activated PKC rather than via the "classic" agonist-surface receptor mechanism, providing an alternative pathway for the induction of leukocyte chemotaxis.