Chemokinetic accumulation of human neutrophils on immune complex-coated substrata: analysis at a boundary.

Abstract

The locomotory behavior of human blood neutrophil leukocytes was studied at a boundary between 2 surfaces with different chemokinetic properties. This was achieved by time-lapse cinematography of neutrophils moving on coverslips coated with BSA [bovine serum albumin], then part-coated with immune complexes by adding anti-BSA IgG with a straight-line boundary between the BSA and the immune complexes. Cell locomotion was filmed in microscopic fields bisected by the boundary, and kinetic behavior was assessed by comparing speed (orthokinesis), turning behavior (klinokinesis), and the rate of diffusion of the cells on each side of the boundary, using a recently described mathematical analysis of kinesis. In the absence of serum or complement, the proportion of motile cells and their speed and rate of diffusion were greater on BSA than on anti-BSE, but there was no consistent difference in turning behavior between cells on the 2 surfaces. The immune complexes were, therefore, negatively chemokinetic in comparison with BSA, and this resulted from a negative orthokinesis with little or no contribution from klinokinesis. As would be predicted theoretically, this resulted in gradual accumulation of cells on the immune complexes even in the absence of a chemotactic factor. A parallel plate flow chamber was used to show that, under conditions of flow, neutrophils accumulated much more rapidly on a surface coated with BSA-anti-BSA than on BSA alone. Neutrophils on immune complex-coated surfaces lost their ability to form rosettes with IgG-coated erythrocytes. Neutrophils on immune complex-coated surfaces may redistribute their Fc receptors (RFc.gamma.) to the under surface. The lowered speed of locomotion could be due to tethering of neutrophils by substratum-bound IgG-Fc.