Chemotaxis by human neutrophils and their cytokineplasts treated with inhibitors of nitric oxide synthase: no suppression of orientation or trajectory.

Abstract

Inhibitors of nitric oxide (NO) synthase are reported to inhibit both the adherence of polymorphonuclear leukocytes (PMN) to substrate and chemotaxis (directed locomotion) of PMN as determined in Boyden chamber assays. In the current study, we examined both human blood PMN and granule-poor motile cytoplasts derived from them (cytokineplasts, CKP), under direct microscopic observation with concomitant time-lapse video recording, for their ability to respond chemotactically to an erythrocyte destroyed by laser microirradiation. In this system we can observe directly and continuously the orientation and trajectory of PMN before, during, and after establishment of a chemotactic gradient. For both PMN and CKP we employed three different inhibitors of NO synthase (N(omega)-methyl-L-arginine, N-iminoethyl-L-ornithine, and diphenyleneiodonium) in at least twice the concentrations employed to inhibit chemotaxis of PMN in Boyden chambers or killing of bacteria in CKP. Although small differences in adhesion might not have been appreciated, treated PMN and CKP were each indistinguishable from untreated controls in their ability to orient in a newly created chemotactic gradient and in their trajectories toward the chemotactic target.