Transplacental transfer of filarial antigens from Wuchereria bancrofti-infected mothers to their offspring.

OBJECTIVE: Maternal infection has been considered to be a risk factor for filarial infection in offspring. In order to examine the influence of maternal infection in neonates, we have determined the prevalence of circulating filarial antigen (CFA) and anti-filarial antibodies in 119 maternal and corresponding cord blood samples collected from an area endemic for bancroftian filariasis.
METHOD: Prevalence of antigenaemia was detected using Og4C3 circulating filarial antigen enzyme-linked immunosorbent assay. The presence of microfilariae was determined by filtration of a 1 ml sample through a Nuclepore membrane. Antibody isotypes (IgG, IgM, and IgE) to filarial antigen (Setaria digitata antigenic extract) were determined by enzyme linked immunosorbent assay (ELISA).
RESULTS: Microfilariae were detected in 14 cases (11.8%), whereas the Og4C3 assay could detect filarial antigen in 44.5% of pregnant mothers. Interestingly, 24.5% of samples born from CFA-positive mothers were found positive for CFA. None of the cord samples from CFA-negative mothers were found positive for CFA. No significant difference was observed in prevalence of filarial-specific IgG, IgM and IgE antibodies in CFA-positive and negative mothers. IgG antibody was detected in 60.5% of maternal and 21.8% of cord samples. IgG antibody in the cord does not differ with the antigen status of the mother. In contrast IgM and IgE antibody prevalence was significantly higher in cord from infected mothers than non-infected mothers (11.3% vs 0 for IgM, 24.5% vs 3.03% for IgE).
CONCLUSION: Our study demonstrates the transplacental transfer of circulating filarial antigen from mother to cord. Filaria-specific IgM and IgE antibodies were higher in cord blood from infected mothers than from non-infected mothers. The findings of the study provide additional circumstantial evidence for pre-natal sensitization to filarial antigens developed in utero.