In vitro antibody-mediated macrophage activity on Breinlia macropi microfilariae. I. Adherence and cytotoxicity

Intense adherence accompanied by cytotoxicity, which initially occurred at 4 h of interaction was observed when the microfilariae of Breinlia macropi were introduced to cultures of quokka peritoneal macrophages previously sensitized in 20% immune serum. No significant difference in the adherence or cytotoxic effects was observed among macrophages from normal, microfilaraemic and amicrofilaraemic quokkas. However, the serum component mediating these effects was found only in microfilaraemic and seropositive amicrofilaraemic quokkas. This mediator was heat-labile and its mediation of the adherence and cytotoxic effects was independent of complement. Because of its apparent dissociation from IgG and its heat lability, the possibility that the mediator resides in the previously-described reaginic antibody of the quokkas was discussed.