Lack of evidence for transplacental transfer of microfilarial antigens in filariasis due to Loa loa and Mansonella perstans.

The transplacental transfer of microfilarial antigens could induce prenatal tolerance, or conversely resistance, which would influence the development of filariasis after birth. The passage across the placenta of immunogens constitutive of a crude microfilarial Loa loa extract has been investigated by dosing specific IgG, IgM and IgE antibodies in 92 maternal and corresponding cord blood samples, IgG levels were shown to be identical in about half of the mother-cord paired samples while in the other half the cord serum had a lower titre. Specific IgM or IgE could not be evidenced in any of the cord blood samples, even from those mothers who where harbouring L. loa microfilariae and/or specific antibodies. It is concluded that prenatal sensitization to the immunogenic preparation used is unlikely to have occurred.