Role of purified serum components in polymorphonuclear leukocyte chemotaxis

Three highly purified serum proteins are examined for their role during leukocyte chemotaxis. In the absence of added proteins, migration of eosinophils towards eosinophil chemotactic factor and of neutrophils towards bacterial factor does not occur at all. Dose-response curves with human serum albumin (HSA) show that chemotaxis proceeds well after addition of HSA, with an optimum at 1 mg/ml. SHA has to be present in the buffer during chemotaxis since preincubation of cells followed by washing is ineffective. In contrast, alpha 2-macroglobulin and alpha 1-antitrypsin enhance leukocyte migration at doses close to physiological serum levels and affect cells irreversibly. The data suggest a complex and powerful modulating influence of serum proteins on the influx of eosinophils and neutrophils to tissue sites.