Detection of microfilarial antigen in circulating immune complex from sera of Wuchereria bancrofti-infected...

Polyethylene glycol-precipitated circulating immune complexes (CICs) from the sera of patients with Bancroftian filariasis were examined for parasite antigen content by an ELISA. Of the 227 patients, 214 were asymptomatic microfilariae carriers with microfilaremias ranging between six and 14,000/ml blood, and 13 were symptomatic patients with chronic filariasis without microfilaremia. In addition, the sera of 10 of the patients treated with diethyl carbamazine were also examined. These assays were devised using mouse monoclonal antibody raised against microfilariae of Wuchereria bancrofti. Using an acid-phase covalent-bound plate for the ELISA makes it possible to assay the antigen contents simply. Microfilarial antigens were detected from 92 (43.0%) of microfilaria (mf)-positive individuals. Furthermore, the level of antigen in CIC was correlated with mf counts from night blood Nuclepore filtration results. Antigen was not detected in CIC from patients with a variety of nonfilarial helminth infections. These findings indicate that microfilariae play an important role of CIC formation in lymphatic filariasis.