THE METABOLISM OF PLATELET-ACTIVATING-FACTOR IN SEVERE AND CEREBRAL MALARIA

In order to examine the effects of platelet-activating factor (PAF) in complicated Plasmodium falciparum infections, plasma concentrations o f lyso-PAF, stable metabolite and principal precursor of PAF were meas ured in 25 Vietnamese adults with severe malaria. The concentration of PAF in the cerebrospinal fluid (CSF) was determined in a sub-group of 23 comatose patients and together with that of lyso-PAF, in the plasm a of 20 patients on recovery of consciousness. The concentration of ly so-PAF in the plasma was depressed on admission to hospital (median [r ange]; 21 [8-143] vs. 293 [215-410] ng/ml in 10 controls; P < 0.001). There was, however, no change in plasma activity of acetylhydrolase wh ich converts PAF to lyso-PAF (P < 0.01 vs. controls) while simultaneou s reduction in the concentration of lipoproteins associated with lyso- PAF were less than those of lyso-PAF per se in the plasma. The plasma concentration of lyso-PAF on admission was associated with parasitaemi a and the concentration of serum triglycerides (r(s) = -0.42, P = 0.04 in each case), the latter being consistent with hepatic effects of PA P reported in previous studies. CSF concentrations of PAF on admission were low (2.3 [0.5-7.7] vs. 0.9 [0-2.5] ng/ml after recovery, P < 0.0 1) compared with values reported previously in bacterial meningitis. P lasma concentrations of lyso-PAF after recovery lay between admission and control values. While increased availability of PAF may reflect pa rasite burden and may modulate liver-mediated metabolic disturbances s uch as hypoglycaemia and lactic acidosis, the role of PAF in cerebral malaria is uncertain.