Cell-mediated and monoclonal antibody-dependent killing of Onchocerca volvulus microfilariae.

To identify the target antigens implicated in the adherence and killing of microfilariae (mf) by leucocytes, we incubated nodular mf and leucocytes in the presence of anti-cuticular monoclonal antibodies (MOVs) and fresh serum. Leucocyte donors were patients with a mean age of 37 years (with 0-1 mf/snip), who had lived in the endemic village studied for at least 10 years. After 16-20 h of incubation, up to 74% of the mf could be seen with 10 or more cells adhering to them. By 36-40 h up to 54% of the mf had been killed by the leucocytes in the presence of a cocktail of monoclonal antibodies termed MOV GIV. The degree of killing in control experiments with the monoclonal antibody MOV 1 remained lower (P less than 0.05), ranging from 0.0 to 4.5% of mf with initial viability of 90-95%. Western blotting revealed MOV GIV prominent target antigens of 10.5, 18.0, 23.5 and 27 kDa in crude surface extracts of female O. volvulus. The detected antigens may play a role in host protection.