Enhancement of human eosinophil- and neutrophil-mediated killing of schistosomula of Schistosoma mansoni by reversed type (IgE-mediated) anaphylaxis, in vitro.

Using human peripheral blood leucocytes we have developed a model for studying the effect of in vitro anaphylaxis on granulocyte-mediated killing of helminthic larvae (schistosomula (Sch) of Schistosoma mansoni). Leucocytes were incubated with either an F(ab')2 rabbit anti-human IgE (alpha E) or a control F(ab')2 prepared from non-specific rabbit IgG (alpha Ec). A time-dependent enhancement of eosinophil- and neutrophil-mediated complement (C) or antibody- (Ab) dependent killing of Sch was observed following incubation with alpha E, but not alpha Ec. Optimal enhancement of granulocyte killing was dependent on the concentration of alpha E, pre-incubation of granulocytes with alpha E prior to addition to C coated Sch, as well as the granulocyte: Sch ratio. Baseline killing of Ab and/or C coated Sch by eosinophil rich cells was significantly greater than neutrophil rich suspensions and both were proportionally increased following incubation with alpha E. Enhanced eosinophil and neutrophil killing by alpha E required the presence of mononuclear cells containing basophils, whereas there was no difference in the killing of C or Ab coated Sch when eosinophils or neutrophils alone were incubated with alpha E or alpha Ec. This IgE and leucocyte-dependent model might facilitate the isolation and identification of the pharmacological mediator(s) of hypersensitivity which enhance eosinophil or neutrophil killing of appropriately opsonized helminthic larvae.