REVERSIBLE PRIMING AND PROTEIN-TYROSYL PHOSPHORYLATION IN HUMAN PERIPHERAL NEUTROPHILS UNDER HYPOTONIC CONDITIONS

Hypotonic shock enhanced both formyl-methionyl-leucyl-phenylalanine (FMLP)-induced superoxide (O2-.) generation and tyrosyl phosphorylation of cellular proteins including 120-, 115-, 83-, 63-, and 54-kDa proteins of human peripheral neutrophils. The time course of the enhancement correlated with that of tyrosyl phosphorylation of the 115-kDa protein. The 'primed state' was reversed to the nonprimed resting state by changing the conditions from hypotonic to isotonic, with a concomitant decrease in tyrosyl phosphorylation. Genistein inhibited the increase in both O2-. generation and tyrosyl phosphorylation of the 120-, 115-, 63-, and 54-kDa proteins. These results suggest the involvement of tyrosyl phosphorylation of a cellular protein(s) in hypotonic shock-induced priming of neutrophils. © 1993 Academic Press, Inc.