Human Mononuclear Leukocyte Chemotaxis: A Quantitative Assay for Humoral and Cellular Chemotactic Factors

Abstract

The participation of the mononuclear leukocyte (MNL) in wound healing and in host immunity is well documented (1, 2). Despite this, the mechanism by which these cells accumulate in local tissue sites is poorly defined. Recent studies have shown that MNLs derived from rabbit or guinea pig inflammatory exudates can respond chemotactically to various stimuli in vitro (3–6; M. S. Hausman, R. Snyderman and S. E. Mergenhagen, submitted for publication). However, quantitative methods for the study of human MNL chemotactic activity have not been previously reported. An assay of human MNL chemotaxis would allow a clearer definition of human MNL chemotactic factors and also the assessment of MNL function in various human disease states. The present report describes a reproducible, quantitative assay for humoral and cellular factors of human origin which are chemotactic for human MNLs. Materials and Methods. Source of MNLs. Blood was drawn from healthy adult laboratory personnel into heparinized (approx. 10 µ/ml blood) syringes. Mononuclear cells were separated from erythrocytes and granulocytes by a modification of the Ficoll-Hypaque method (7). All cell washes were performed with Gey's balanced salt solution at pH 7.0 (M. S. Hausman, R. Snyderman and S. E. Mergenhagen, submitted for publication). The cells were resuspended at a concentration of 5 × 106 mononuclear cells/ml. They consisted of approximately 30% large monocytes and 70% small lymphocytes.