The effect of immune serum and complement on the in vitro phagocytosis of Babesia rodhaini

Abstract

The effect of immune serum and complement on the in vitro phagocytosis of Babesia rodhaini was investigated. Infected erythrocytes and parasites released from erythrocytes by lysis were phagocytosed by mouse peritoneal macrophages in vitro when the infected erythrocytes or parasites were exposed to hyperimmune B. rodhaini serum. Complement, in the presence of immune serum, did not reproducibly enhance phagocytosis of infected erythrocytes or parasites alone. When adjusted for its effect on normal erythrocytes and normal serum, complement generally inhibited rather than enhanced phagocytosis. When coupled with other published data, our data suggest that the activation of the immune system in vivo against this species of Babesia involves a series of mechanisms of which phagocytosis is but one.