Chemotaxis, spreanding nd oxidative metabolism of neutrophils: influence of albumin in vitro.

Studies on polymorphonuclear leukocyte (PMN) migration in vitro have shown that albumin increases the speed of the cells without affecting their orientation, i. e. chemokinesis. In order to analyze this phenomenon the effect of albumin on PMN migration in a Boyden chamber towards various chemotactic agents was examined. On attraction with low molecular weight chemotactic factors (a culture filtrate of E. coli (BCF)) or the synthetic peptide N-Formyl-Methionyl-Leucyl-Phenylalanine (F-Met-Leu-Phe) albumin enhanced the migration of PMN. In contrast, albumin did not enhance the migration towards casein, a high molecular weight chemotactic factor, except at very low concentrations. In a direct visual assay, albumin was found to impair PMN spreading on a polystyrene Petri dish. In the presence of BCF or F-Met-Leu-Phe cell spreading remained inversely related to the concentration of albumin, while addition of casein again eliminated the influence of albumin. The effect of albumin on the interaction of PMN with a substrate was studied by measuring the superoxide anion (02-) release by PMN sedimenting on a micropore filter. The 02- release triggered by this stimulus of the PMN membrane was inversely correlated to the concentration of albumin. These results show that one mechanism of the enhancing effect of albumin on PMN migration is to diminish adhesion of the cells to the substratum, so that it remains reversible. It is suggested that the term chemokinesis is equivocal. The chemokinetic activity of chemotactic factors would be the result of specific stimulation of PMN locomotion. In contrast, the chemokinetic activity of albumin is due to changes of the physico-chemical environment which support PMN locomotion.