Studies on Dipetalonema viteae (Filarioidea) 3. Antibody-dependent cell-mediated destruction of microfilariae in vivo.

Antibody-dependent cell-mediated destruction of Dipetalonema viteae microfilariae could be demonstrated in the golden hamster using a micropore chamber technique. Microfilariae were eliminated within 24 hours in chambers of 3.0 and 5.0 microm pore size when implanted into amicrofilaremic hamsters (week 30 post infection). At peak microfilaremia (week 12 post infection), only some hamsters could efficiently destroy microfilariae. In chambers with 0.3 microm pore size, microfilariae survived for more than 3 weeks in all hamsters. In uninfected hamsters, microfilariae could only be eliminated if they had been preincubated with serum or its 19S fraction containing antibodies to the cuticle of microfilariae. The opsonizing activity of the serum was abolished by 2-mercaptoethanol treatment. The composition of cells adhering to microfilariae was always significantly different from the composition of cells which migrated into a chamber. The adhesion patterns on individual microfilariae indicated that no single effector cell type was responsible for the destruction of microfilariae. The eosinophil was the predominant cell type but neutrophils, lymphocytes and monocytes also adhered to the microfilariae. Cellular adhesion led to the immobilization of microfilariae and subsequently to their disintegration within large cell clusters. During the final stages of destruction the contribution of the monocyte became more pronounced.