Activation of arachidonic acid metabolism during aggregation of polymorphonuclear granulocytes

The role of neutrophil aggregation in arachidonic acid metabolism and of the phospholipid components of the cellular membrane were investigated. PMNs aggregated in response to different substances (PHA, PMA, FMLP, Thrombin, Trypsin). PHA-induced aggregation was associated with the production of TxB₂ and LTC₄; ASA at 0.3, 0.5 and 1.0 mM concentrations significantly decreased neutrophil aggregation and TxB₂ production and slightly increased LTC₄ production. Phospholipases A₂, C and D preincubated with PMN suspension reduced PHA-induced aggregation. These results suggest that the activation of arachidonic acid metabolism is involved in PMN aggregation and ASA seems to modify only the prostaglandin biosynthesis pathway. The phospholipid components of the cellular membrane are essential in the aggregation of stimulated PMNs.