Cellular killing of microfilariae of Onchocerca volvulus: Eosinophil and Neutrophil-Mediated immune serum-dependent destruction

Abstract

A system that demonstrates in vitro cell-mediated killing of microfilariae of O. volvulus has been developed, using cryopreserved nodule material from endemic areas as the source of microfilariae (Mf). In the presence of immune serum, normal neutrophils and eosinophils, purified using a discontinuous metrizamide gradient, showed enhanced adhesion of Mf, which led to their immobilization and destruction over a 6- to 18-hr period. Peripheral blood mononuclear cells did not attach to or kill Mf. Immunofluorescent staining revealed IgG binding to the surface of microfilariae after incubation in immune serum, but no IgM, IgA, or IgE. The addition of fresh normal human serum (FNHS) increased eosin..