Abstract
We have evaluated in in vitro conditions the possible cooperative effect of antimalarial antibodies with several human blood cell types. When used alone, immunoglobulin G from African adults who had reached a state of premunition against malaria was found to have no or very limited direct effect on invasion and multiplication of P. falciparum asexual blood stages. In contrast, these antibodies induced a marked specific inhibition of parasite growth in the presence of normal blood monocytes, and the inhibition did not appear to be strain dependent. No similar antibody-dependent cellular inhibitory effect was found using human blood polymorphonuclear leukocytes, lymphocytes, platelets, or adherent spleen cells. However, these cells could all exert in vitro some non-antibody-dependent inhibitory effect when present at high effector/target cell ratios.