Influence of inhibitors of cellular function on chemotactic factor-induced neutrophil aggregation

Chemotactic factors which induce polymorphonuclear neutrophils (PMN) to migrate directionally and release granular enzyme constituents also induce these cells to aggregate. The potency of these factors in inducing aggregation closely parallels their chemotactic and enzyme-releasing potencies. Several reagents known to influence the migratory and degranulatory response of PMN to chemotactins have been examined for their influence on chemotactic factor-induced aggregation of PMN. We have found that ambient temperatures below 37 degrees C, deoxyglucose, and iodoacetic acid inhibit PMN aggregation, whereas sodium cyanide and dinitrophenol have no effect. Inhibitors of microtubules (colchicine and vinca alkaloids) and of protein synthesis (cyclohexamide) had no effect. Cytochalasin B markedly enhanced aggregation. We conclude that chemotactin-induced aggregation is similar to the other chemotactin-induced PMN functions in the requirements for proper temperature and intact glycolytic pathways; in contrast, however, and intact cytoskeletal microtubular system appears unessential for this response. This may be explained by assuming that the chemotactic factor-induced aggregation of PMN is predominantly a surface membrane-dependent phenomenon.