Analysis of human sera for filarial IgM antibody using antigen fractions isolated from immune complexes.

Filarial IgM antibody response to various antigenic fractions isolated from immune complexes by SDS-PAGE viz., IC-2, IC-4, IC-7, and IC-9, was studied by ELISA. The IgM antibody response to almost all antigenic fractions was seen more in microfilaraemic group compared to the clinical filariasis group. The antibody response to IC-9 antigen fraction as compared to other fractions was found significantly higher in microfilaraemic patients than in patients with clinical manifestations. Ninety percent of microfilariae carriers and 75% of clinical filarial patients have shown IgM isotype to IC-9 antigen. Studies with various lectins have revealed the Con A binding nature of IC-9 antigen. This study suggests that IC-9 antigen could be another candidate antigen in the immunodiagnosis of lymphatic filariasis.