ヒト好中球機能とチロシンリン酸化

Abstract

Activation of human neutrophils by the chemotactic peptide formyl-methionyl-leucyl-phenylal-anine ( FMLP), phorbol myristate acetate ( PMA ) and calcium ionophore (ionomycin) consistently and predominantly induced tyrosine phosphorylation of a microtubule-associated protein kinase (MAPK) . The dose-resposne curves showed that tyrosine phosphorylation and O-2 release were stimulated in parallel by PMA, whereas tyrosine phosphorylation and an increase in [Ca2+] i, but not O-2 release, were stimulated in parallel by FMLP or ionomycin. The potency of inducing tyrosine phosphorylation was ionomycin>FMLP=PMA, whereas the potency of triggering of O-2 release was PMA>ionomycin = FMLP. Tyrosine kinase inhibitor (genistein) inhibited O-2 release induced by FMLP, but not by PMA, However, genistein did not impair FMLP-or PMA-induced tyrosine phospho-rylation of MAPK. UCN-01, a protein kinase C inhibitor, inhibited O-2 release and tyrosine phosphorylation of MAPK induced by PMA, but not by FMLP. Increased tyrosine phosphorylation of MAPK was also detected in immature myeloid cells (HL -60 cells) stimulated by PMA and FMLP, but not by ionomycin.These findings suggest that tyrosine phosphorylation of MAPK is induced by the PKC dependent and independent mechanisms according to the stimuli, and the PKC-independent and ionomycin-sensitive mechanism is inoperative in HL-60 cells and tyrosine phosphorylation of MAPK is unlikely to be causally related to activation of the respiratory burst.