Sensory neuropeptides (substance P) and 4-11 SP enhance human neutrophils chemiluminescence; the role of L-arginine

Investigations on the effect of a naturally occurring neuropeptide, substance P (SP) and one of its synthetic analogues, 4-11 SP, on luminol-enhanced chemiluminescence (CL) of human polymorphonuclear leukocytes (PMN) are presented. Both Peptides elicited a strong burst of CL with different time course and dose-response curves. SP- and tuftsin-induced CL were similar, both Peptides sharing a Lys-Pro-Arg terminal; 4-11 SP, which lacks the terminal arginine, peaked earlier than the natural peptide. Surprisingly when PMN were pre-incubated with L-arginine (L-Arg) this enhancing effect was abolished or diminished. L-Arg and an L-Arg synthetic derivative (PCF-39) were also evaluated; PCF-39 strongly increased the PMN CL, while L-arginine showed a significant CL enhancement only in 43% of the donors tested. Peptide- and arginine-induced CL were Ca++/MG++ dependent.