A role for antibody and Fc receptor in the clearance of Brugia malayi microfilariae.

The roles of antibodies (Ab) and Fc receptors (FcR) in clearance of Brugia malayi microfilariae (Mf) in vivo have not been previously elucidated. Different background strainsof mice clear Mf at different rates and we established that there were no major differences in Ab production between three particular strains. However, genetic immunodeficiencies in B cell and Ab production on each of these background strains significantly enhanced Mf survival. B cell-deficient microMT (C57BL/6) mice injected with B. malayi Mf i.v. retained significant numbers of live Mf in comparison to wild-type mice. Treatment of microMT mice with hyperimmune whole sera in the first week of infection significantly reduced the number of Mf surviving in the cardiac blood at 135 days p.i. Mf survival in FcRgamma-deficient (Sv129xC57BL/6) mice was also dramatically increased in the cardiac blood compared to wild-type mice, indicating that Ab itself is involved in Mf clearance most likely via a mechanism involving ADCC. These data indicate that Ab plays an important role in vivo in Mf killing in mice and this role is mediated via the FcR.