NEUTROPHIL PLATELET-ACTIVATING-FACTOR PRODUCTION AND ACETYLTRANSFERASE ACTIVITY IN CLINICAL ACUTE MYOCARDIAL-INFARCTION

1. Neutrophil function was studied in 10 males presenting with acute m yocardial infarction (MI) within 6 h of onset and in 10 normal males. Neutrophil production of platelet-activating factor (PAF), determined by bioassay, that of leukotriene B-4 by HPLC, and the activity of an e nzyme involved in the synthesis of PAF, acetyltransferase (AT), were m easured before and after stimulation with opsonized zymosan and calciu m ionophore, A23187. 2. The neutrophil count was significantly raised at presentation in those with MI (8.2+/-0.8 vs 2.8+/-0.3 (s.e.m.)x10(9 ) cells/L, P<0.001; t-test, 18 d.f.). Production of PAF per neutrophil in response to both stimulants was greater than normal in those with MI (zymosan: 21+/-4 vs 12+/-1ng/10(7) cells, P<0.05; ionophore: 174+/- 18 vs 113+/-11ng/10(7) cells, P<0.02) despite normal leukotriene B-4 p roduction and depressed AT activity. By 7 days, the neutrophil count h ad significantly fallen but it remained greater than normal as did PAF production. 3. Acute MI is associated with increased potential for pr oduction of PAF by neutrophils which may be important in the pathogene sis of MI.