Neutrophil aggregating properties of PAF-acether and leukotriene B4.

Both leukotriene B4 (LTB4) and platelet activating factor (PAF-acether) induce the aggregation of rat polymorphonuclear leucocytes. PAF-acether, but not LTB4, causes the aggregation of washed rabbit platelets. The results obtained from cross-desensitisation studies and experiments using inhibitors of arachidonic acid metabolism support the concept that LTB4 and PAF-acether have separate receptor sites on the neutrophil cell surface and show that PAF-acether does not induce neutrophil aggregation by releasing LTB4.