Aggregation of polymorphonuclear leucocytes (PMNs) by leukotriene B4: effects of cyclooxygenase products and metabolic inhibitors.

Leukotriene B4 isomer III (LTB4) stimulates the aggregation of rat PMNs in vitro. The effects of deoxyglucose, iodoacetate, dinitrophenol, cyclohexamide, colchicine, prostaglandins and thromboxane B2 (TXB2) on aggregation were examined. The results demonstrate that, first, aggregation is an active process, the energy being supplied by glycolysis and not mitochondrial respiration. The response can be elicited in the absence of extracellular glucose. Synthesis of protein does not occur during aggregation. An intact microtubular system is required for the expression of a full aggregation response. Prostaglandins E1, E2, F2 alpha and TXB2, products of the cyclooxygenase pathway of arachidonic acid metabolism, partially inhibit LTB-4 induced aggregation by a mechanism which has not yet been elucidated. The prostaglandins and TXB2 themselves do not promote aggregation.