IGE ANTIBODY-MEDIATED CYTO-TOXICITY OF RAT MACROPHAGES AGAINST MICROFILARIA OF DIPETALONEMA-VITEAE INVITRO

Abstract

The Fischer rat develops an acquired resistance against circulating microfilariae. Macrophages from the peritoneal washings of normal rats pre-incubated at 37.degree. C with the sera obtained from rats immune to circulating microfilariae adhered to and killed the microfilaria of D. viteae in vitro within 16-24 h. No significant adherence and cytotoxicity was mediated by sera collected from animals with microfilaremia or from normal rats. Adherence of macrophages to microfilaria was associated with damage to the surface of the larva as revealed by ultrastructural studies. Neither adherence nor cytotoxicity was induced by pre-incubation of microfilariae, instead of macrophages with immune serum. The serum factor which mediated adherence and cytotoxicity was heat-labile, but was not a complement component. Immune absorption experiments showed that the relevant serum factor was Ig[immunoglobulin]E antibody. The immune adherence to D. viteae by macrophages is stage-specific because adherence to infective larvae was not observed, whether rat macrophages were pre-incubated in sera obtained from rats immune to microfilariae or in sera collected from animals after exposure to infective larvae.