Priming of human neutrophils by tumour necrosis factor-alpha and substance P is associated with tyrosine phosphorylation.

The mechanisms involved in neutrophil 'priming' are unknown. 'Priming' by substance P and tumour necrosis factor-alpha (TNF-alpha) occurred without effecting cytosolic-free Ca2+ signalling and was independent of actin polymerization. We demonstrate here that these two primers, which act on different receptor classes, both cause tyrosine phosphorylation of a number of protein substrates including a prominent 74,000 MW protein. This protein was not recognized by anti-c-raf antibodies. The concentration relationship and time-course of tyrosine phosphorylation were consistent with a role in mediating priming. Pretreatment with genistein both inhibited tyrosine phosphorylation and abolished the priming by either substance P or TNF-alpha.