Modulation of the H‐2 Antigenicity on the Surface of Murine Peritoneal Cells

Incubation of peritoneal cells in H‐2 antisera abrogated specifically their sensitivity to the cytotoxic effect of these H‐2 antisera and complement. Incubation of the cells in antisera to either the O‐ or Ly alloantigens did not affect their sensitivity to H‐2 antisera. In F₁ hybrid cells, H‐2 antigens determined by one of the parental strains could be modulated by H‐2 antibodies, without affecting the expression of the allelic H‐2 antigens determined by the other parent. Modulation of the H‐2 antigenicity of peritoneal cells resulted from an active metabolic process in the treated cells. The phenomenon was inhibited by exposure of the cells to sodium azide, 2,4 dinitrophenol, iodoacetate, corticosteroid hormones, or colchicine. In contrast, cytosine‐arabinoside, cycloheximide, puromycin, and chloramphenicol had no significant inhibitory effect. It is suggested that modulation of the H‐2 antigenicity of peritoneal cells results from redistribution of the H‐2 antigenicity as a result of pinocytosis.