ABSTRACT
1. The dyslipoproteinemia commonly occurring in the hepatosplenic forms of schistosomiais mansoni in Brazilian patients is characterized by low plasma levels of choleteryl esters and of the cholesterol-esterifying enzyme, lecithin:cholesterol acyltransferase (LCATase, EC.2.3.1.43). 2. In the present study, normal helathy individual and patients sufferin from hepatosplenic schistosomiasis mansoni were comapred for the fatty acyl compositons of circulating plasma cholesteryl esters and of those formed in vitro by the action of LCATase on a) the endogenous plasma lipoprotins and b) an excess of lipoprotein substrate composed of heat-inactivated plasma. 3. In patient palsma the proportions of saturated and monounsaturated cholesteryl esters were higher and those of diunsaturated and polyunsaturated esters were lower than in the control group. 4. Similar differences were observed between patients and controls in the proportions of the cholesteryl ester subclasses formed in vitro by the action of LCATase on endogenous plasma lipoprotins. 5. Incubation of fresh normal or patient plasma with escess heat-inactivated plasma as substrate for LCATase produced proportions of cholesteryl ester subclasses similar to those formed dduring incubation of nonheated aliquots of the appropriate plasma. 6. We conclude that the alterations in fatty acyl composition of palsma cholesteryl estes in patients with hepatosplenic schistosomiasis mansoni do not appear to be direct consequence of the low levels of LCATase acivity in patient plasma