Diets high in polyunsaturated oils decrease lymphocyte membrane anisotropy and B-cell mitogenesis

Balb/c mice were fed semipurified diets containing 40% of total calories as lipids: olive, safflower, or fish oil. After 2 weeks of feeding, splenic mononuclear cells were isolated and assayed for steady-state fluorescence anisotropy by means of the probe diphenylhexatriene. Splenocytes were also incubated with the mitogens concanavalin A, phytohemagglutinin, or lipopolysaccharide; subsequent uptake of tritiated thymidine was measured as an index of proliferation. No differences were observed in the membrane anisotropy and mitogenesis of mice fed the olive oil diet (high in monounsaturated fatty acids) and the control group. However, membrane anisotropy was significantly lowered in mice fed the safflower or fish oil diets (high in polyunsaturated fatty acids), and the mitogenic response to lipopolysaccharide was suppressed. Mitogenic responses to concanavalin A and phytohemagglutinin were not significantly affected by the type of lipid in the diet.