Trilinolein potentiates the pro-aggregating effect of phorbol-12- myristate 13-acetate in human polymorphonuclear leukocytes

Trilinolein, a triacylglycerol with linoleic acid as the only type of fatty acid residue in all three of the glycerol esterified positions, was recently reported to have an antiplatelet effect, mediated through stimulating nitric oxide and cyclic guanosine monophosphate (GMP) formation. In our study, trilinolein induced aggregation of human polymorphonuclear neutrophils (PMNs) and, pretreatment with 0.1 nM trilinolein enhanced phorbol-12-myristate 13-acetate (PMA) induced aggregation. Further investigation showed that trilinolein at concentrations ranging from 0.1 nM to 10 μM increased cyclic GMP formation after 10 min of incubation with PMNs. Pretreatment of trilinolein with 10 μM d-sphingosine, before being incubated with PMNs, attenuated the stimulatory effect of trilinolein on cyclic GMP formation, and pretreatment of 10 μM d-sphingosine also attenuated the aggregation induced by PMA and trilinolein. We conclude that trilinolein can induce the aggregation of human PMNs, and enhance the aggregation induced by PMA.