Mechanisms of Protective Activities of Monoclonal Antibodies Against Malaria Parasite Plasmodium Falciparum

A range of monoclonal antibodies specific for Plasmodium falciparumwere tested in vitro for their abilities to inhibit the multiplication of a partiallysynchronized culture of P.falciparum,to augment the phagocytosis of theparasites by macrophages,and to enhance the hilling of parasites by peritonealcells depleted of adherent cells.Seven of 17 monoclonal antibodies,ranging fromculture supernatant and ascitic fluid to purified IgG,were shown to have a dose-and time-dependent inhibition of the parasite growth in vitro.At a concentrationof 0.6mg/ml,the inhibitory capacity of these monoclonal IgG was above 94% overa 3-day culture period,much higher than that of the relevant polycloaal IgG.Four of six monoclonal antibodies tested augmented the phagocytosis of theparasite by macrophages,resulted from the opsonization of the parasites.Four ofthe seven monoclanal antibodies examined showed cytotoxic activity on malariaparasites.Peritoneal cells depleted of adherent cells were capable of killing theparasites in the presence of monoclonal antibodies.The results indicate that theremay be“monofunction”,“bifunction”,and“multifunction”types of monoclonalantibodies against P.falciparum.The putative protective antigen of malariaparasite purified by“multifunctional monoclonal antibody”affinity chromatographymay have potential interest as a vaccine against the parasite.

Mechanisms of Protective Activities of Monoclonal Antibodies Against Malaria Parasite Plasmodium Falciparum