BABESIA-BOVIS - INVITRO PHAGOCYTOSIS PROMOTED BY IMMUNE SERUM AND BY ANTIBODIES PRODUCED AGAINST PROTECTIVE ANTIGENS

The in vitro phagocytosis of both Babesia bovis-infected red cells and of parasites exposed by lysis of infected red blood cells is demonstr ated in a phagocytic mouse model. Twenty-four B. bovis immune sera wer e tested alone or as a pool as were antibodies (DS antibodies) raised against a B. bovis protective fraction, prepared by dextran sulfate pr ecipitation. All the immune sera failed to promote significant levels of phagocytosis, whereas the other antibodies (DS antibodies) consiste ntly induced phagocytosis of infected cells in all the experiments car ried out. This study shows that antibody specificity is critical to th e opsonization of infected red cells and parasites during in vitro pha gocytosis and suggests that phagocytosis is one of the mechanisms in t he in vivo immune response against Babesia species.