Increased IgG antibody responses to excretory/secretory antigens in neonates born from mothers infected with filarial nematodes.

The present investigation aimed to evaluate the extent to which maternal filarial infection influences IgG subclass immune responses in the cord blood of neonates. Prevalence of antigenaemia was detected using an Og4C3 assay. Filaria-specific IgG subclasses against excretory/secretory antigens were measured by ELISA. Transplacental transfer of circulating filarial antigen (CFA) was observed from 34.8% of CFA-positive mothers to their respective cord bloods. Filaria-specific IgG1, IgG2 and IgG4 responses were significantly higher among cord bloods of infected mothers compared to cord bloods of uninfected mothers. In contrast, the IgG3 response was significantly higher among cord bloods of uninfected mothers. The study shows that transplacental transfer of filarial antigens and filaria-specific IgG4 occurs more in mothers having high worm burdens, and transfer of filaria-specific IgG3 occurs more in the cord blood of uninfected mothers. The findings of the study provide evidence for the development of prenatal sensitization to filarial antigens in utero, and high filaria-specific IgG4 in cord blood may serve as a marker for in-utero sensitization.