In vitro human polymorphonuclear leukocyte chemokinesis and human monocyte chemotaxis are different activities of aminoterminal and carboxyterminal substance P.

Polymorphonuclear leukocytes (PMNL) are a component of the inflammatory response to neurogenic mediators. Using the micropore filter approach, the authors studied the chemoattracting properties of tachykinins, including substance P (SP), neurokinin A (NKA) and neurokinin B (NKB), and that of calcitonin gene-related peptide (CGRP) for human PMNL in vitro and now show that SP in near nanomolar concentrations stimulates locomotion of human PMNL. Locomotion of PMNL is induced by SP, aminoterminal SP (1-9) and the SP receptor antagonist [D-pro2, D-trp7,9]-SP (DPDT) but not by carboxyterminal SP (3-11), NKA, NKB, or CGRP suggesting that the aminoterminal amino acids arginine and proline are essential residues of SP in activation of PMNL locomotion. In contrast, the migratory effect of SP on monocytes resides in the carboxyterminal SP amino acid sequence, which is in agreement with carboxyterminal, SP receptor-mediated chemotaxis of human monocytes previously shown by others. From the known structure-activity relationships for SP receptors it is concluded that induction of PMNL migration by SP does not involve neurokinin-1 (NK-1), NK-2 or NK-3 receptors. "Checkerboard" analysis reveals that PMNL locomotion by SP is not dependent on concentration gradients and thus represents chemokinesis, which is enhancement of speed and/or frequency of locomotion. One cannot exclude that this action of SP on PMNL is mediated by the aminoterminal sequence via yet unknown SP "receptors".(ABSTRACT TRUNCATED AT 250 WORDS)