Evidence for in utero sensitization to Ascaris lumbricoides in newborns of mothers with ascariasis.

Ascaris lumbricoides infections in humans may have important effects on the development of allergy and on susceptibility to infectious diseases that start during early life. To investigate whether sensitization to A. lumbricoides occurs in utero, we measured interferon (IFN)-gamma and interleukin (IL)-4 responses in A. lumbricoides antigen-stimulated cord blood from newborns of infected and noninfected mothers by flow cytometry. There was evidence of higher frequencies of IFN-gamma-expressing and IL-4-expressing CD4+ T cells in newborns of infected mothers than in newborns of noninfected mothers. Our data provide evidence of in utero sensitization to A. lumbricoides and raise the possibility that the immunological effects of infection start in the fetus.