Immune-complexes-mediated evasion of Plasmodium knowlesi from destruction by macrophages

Abstract

The role of immune-complexes in the evasion of Plasmodium knowlesi from destruction by macrophages was studied in vitro. Incubation of macrophages with immune-complexes, prepared either by mixing total parasite antigens soluble in culture medium with normal or immune monkey serum, or by polyethylene glycol precipitation of serum from monkeys acutely infected with P. knowlesi, significantly reduced both the pool size of the macrophages that bound parasitized erythrocytes, and the number of parasitized erythrocytes bound per macrophage. Parasitized erythrocytes with mature schizonts were invariably preferred over those containing rings. These observations appear to indicate that during P. knowlesi infection in rhesus monkeys, immune-complexes may inhibit the binding of parasitized erythrocytes with mononuclear phagocytes and thus may enable them to evade the destructive mechanisms mounted by the host.