Reversible Priming and Protein-Tyrosyl Phosphorylation in Human Peripheral Neutrophils Under Hypotonic Conditions

Hypotonic shock enhanced both formyl-methionylleucyl-phenylalanine (FMLP)-induced superoxide (O−.2) 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 1 15-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 O−.2 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.