The biological role of calcium in adult and neonatal neutrophil chemotaxis.

Comparative chemotaxis studies of adult and newborn polymerphonuclear leukocytes (PMNs) were performed by a technique which adapted the micro-pore filter method to a multiwall chamber. Cord blood neutrophils responded to the chemoattractant FMLP with 60% of adult PMN activity. In order to investigate the defect of neonatal PMN chemotaxis as a calcium-associated phenomenon, PMNs wre suspended in a calcium-deprived buffer and in the presence of the calcium channel blocker, verapamil, before being assayed for migration. Adult neutrophils responded to both calcium manipulations with reduced chemotaxis as expected-19% inhibition in calcium-deprived media (p<0.05), and 32% reduction (p<0.001) with 10[-4] M verapamil, Neonatal PMNs, however, increased chemotactic activity in the absence of extracellular calcium-26% (p<0.05) and to a greater extent in the presence of 10[-4] M verapamil (p<0.001). This suggests that the flux of calcium which occurs upon stimulation of the neutrophil by chemotactic factors may, in fact, be responsible for the neonatal defect and the inhibitory concentrations of intracellular calcium may be present in the neonatal cell.