Aggregation of rat polymorphonuclear leukocytes in vitro by chemotactic factors (Abstract)

Abstract

Rat leukocytes containing 84 ± 4% polymorphonuclear leukocytes (PMNs) were obtained by peritoneal lavage 24 h after the injection of 6 ml of 12% sodium caseinate. The cells were washed and resuspended at a concentration of 1–1.3 × 10⁷ cells/ml in Eagle’s minimum essential medium buffered to pH 7.4 with 30mmol/l HEPES. The change in particle numbers reflecting aggregation was measured by the decrease in optical density in a Payton aggregometer (37°C, 900 rev/min stirring speed). Both formyl-methionyl-leucyl-phenylalanine (FMLP), over the range 10^-5-10^-8 mol/1 and zymosan activated serum or plasma, over the range 0.5–10% v/v, produced dose related aggregation responses. The reaction was diminished in the presence of 0.5% human serum albumin and potentiated in the presence of cytochalasin B (optimal concentration 250 ng ml^-1). The optimal cell concentration was found to be 1.2 × 10⁷ cells/ml and the technique was highly reproducible (coefficient of variation <8.5%). The aggregation of peripheral rat PMNs in response to FMLP was significantly reduced when compared to that of elicited peritoneal cells.