Recombinant gamma interferon enhances the synthesis of platelet activating factor by immune complex-triggered polymorphonuclear leukocytes

GEFFNER JR; SCHATTNER M; LAZZARI M; ISTURIZ M

Tokio, Japón

Congreso; XII Congress of the International Society on Thrombosis and Hemostasis; 1989

RECOMBINANT GAMMA INTERFERON ENHANCES THE SYNTHESIS OF PLATELET ACTIVATING FACTOR BY IMMUNE COMPLEX-TRIGGERED POLIMORPHONUCL LEUKOCYTES. J.Geffner*, M.Schattner**, M.Lazzari *and M.Isturiz*. Immunology Section*, Thrombosis Section**, Haematological Research Institute. National Academy of Medicine. Buenos Aires. Argentina. In this study, we analized the effect of gamma interferon on the capacity of immune complex(IC) triggered polymorphonuclear leukocytes (PMN) to produce platelet activating factor (PAF). Peripheral blood PMN were isolated from heparinized human blood by sedimentation in dextran and Phicoll-Hypaque centrifugation. Precipitating IC were prepared with rabbit IgG anti-ovoalbumin and chromatographically purified ovoalbumin. PMN (3x106 alone or treated with gamma interferon (100 U/ml) were incubated during 12 hr at 37°C and then triggered with IC (50 ìg/ml). After 10 min the reaction was stopped by placing cell suspensions into glass tubes containing chloroform, acidified methanol. The chloroform phase was evaporated under a nitrogen stream and the lipid extracts were suspended in 400 ìl of BSA-Tyrode buffer. PAF was detected by its ability to aggregate washed rabbit platelets (4x108 ml) pretreated with indomethacin and apyrase. The results were expressed in pmol PAF, calculated over a calibration curve stablished with synthetic PAF. PAF in the lipid extracts was characterized by 1)sensitivity to phospholipase A and 2) disapperarance of the aggregation response when platelets were pretreated with the specific PAF-antagonist BN 52021(10-5M). Aliquots (100 lì) from either untreated or treated with gamma interferon PMN were not able to induce aggregation. IC-triggered PMN produced 4.5 ± 1.3 pmol of PAF (X ±SE, n=8). This response was greatly enhanced (p<0.0005) when PMN were pretreated with gamma interferon:18.4±7.0 pmol of PAF (n=8) Our results demonstrate that gamma interferon is a potent modulator of PAF production by PMN.