Effects of dietary cholesterol on antibody-dependent phagocytosis and cell-mediated lysis in guinea pigs.

The effect of dietary cholesterol on antibody-dependent phagocytosis and cell-mediated cytotoxicity (ADCC) by peritoneal cells and on the susceptibility to lysis of erythrocytes was studied in the guinea pig. We found that peritoneal cells from cholesterol-fed animals (CHOL PEC) demonstrated a decreased ability to both phagocytose and lyse antibody-coated (Ab) guinea pig erythrocytes than did those from control guinea pigs (CONT PEC). This decrease was equal in groups fed cholesterol for 5 1/2-13 weeks, preanemic or anemic, and with normal or enlarged spleens. Dose response curves varying Ab concentration showed that CHOL PEC required higher concentrations of Ab to effect phagocytosis and lysis than did CONT PEC. Dietary cholesterol, while rapidly inducing morphological changes such as spurring in guinea pig erythrocytes, was found not to affect the susceptibility of the cells to lysis or phagocytosis in this assay system. These findings suggest that the increased incidence of infection in cholesterol-fed guinea pigs may be due to impaired phagocytic function and that the anemia observed in guinea pigs after 8-10 weeks of feeding cholesterol is not due to increased antibody-dependent removal of spurred erythrocytes by the phagocytic system.