The utility of human filarial serum in the detection of circulating antigen.

The utility of human filarial serum immunoglobulin (FSI) in detecting circulating antigen in filarial sera was studied by counter immunoelectrophoresis (CIEP) and the indirect haemagglutination test (IHAT). CIEP was found to be better than IHAT. 23 out of 30 sera from persons with microfilaeremia and one of 30 clinical cases of filariasis, but none of the normal sera or sera from those with helminths other than filariae, showed the presence of circulating filarial antigen in CIEP. FSI was fractionated by DEAE- Sephadex A-50 column chromatography and the antibody active in CIEP was found to be IgG in nature.