Plasmodium berghei: electron spin resonance and lipid analysis of infected mouse erythrocyte membranes.

Red blood cells from mice infected with Plasmodium berghei and from uninfected mice were labeled with stable, free radical derivatives of stearic acid. Electron spin resonance spectra of these samples showed that the degree of molecular order in these membranes decreased, and the rate of motion of the probe increased, with increasing levels of parasitemia. Parasitemia increased the ratio of unsaturated to saturated 18-carbon fatty acids, and decreased the percentage of arachidonic acid and of cholesterol. The effects of parasitemia on the membrane properties correlated with decreases in cholesterol/fatty acid ratios.