Analysis of IgG subclasses and IgE antibodies across the clinical spectrum of bancroftian filariasis in an endemic area.

Analysis of immune response in individuals with different clinical manifestations living in filaria endemic area will be of interest to understand the immunological events associated with the disease development in filaria infected endemic population. The levels of four IgG subclasses and IgE antibodies against Brugia malayi microfilarial excretory-secretory (Bm mf ES) antigen as well as circulating filarial antigen level were evaluated in 84 individuals belonging to different groups in an endemic area for bancroftian filariasis. Microfilaraemics showed significantly elevated levels of IgG4 and IgG3 antibodies compared to endemic normals (P < 0.02). As many as 70% of this group were positive for IgG4 & IgG3 antibodies. While Acute filarial cases had pronounced IgG1 antibodies(P < 0.001), the Grade I chronic cases showed higher levels of IgG3 and IgG4 antibodies (P < 0.02), Occult filarial cases had higher levels of IgG4 and IgG3 (P < 0.02) and also of IgG4 antibodies (P < 0.001). IgE antibodies were found to be elevated in microfilaraemics as well as other clinical filarial groups. Circulating filarial antigen was detected in 95% of microfilaraemics, 60% of acute cases, 75% to 90% of different grades of chronic filarial cases, 100% of occult cases and none of the endemic normals.