Impact of in utero Th2 immunity on T cell deviation and subsequent immediate-type hypersensitivity in the neonate.

It was the aim of this study to analyze the impact of maternal Th2 immune responses on onset and subsequent development of allergen-specific immunity and immediate-type hypersensitivity in early childhood. In a well characterized mouse model of Th2 immunity, BALB / c mice were sensitized to ovalbumin (OVA) before mating followed by allergen aerosol exposure during pregnancy. At the end of pregnancy mice developed allergen-specific Th2 / Th0 immunity and immediate-type hypersensitivity responses to OVA. T cells from these newborns, when restimulated with PMA / ionomycin, demonstrated a lowered capacity to produce IFN-gamma. To assess whether prenatal allergen exposure favors postnatal onset of a Th2-type immune response, these offspring were immunized to a novel antigen by a single injection of beta-lactoglobulin (BLG). In contrast to offspring from non-sensitized mothers, offspring from OVA-sensitized mice showed both higher anti-BLG immunoglobulin titers and higher frequencies of immediate-type skin test responses. Our data suggest that Th2 / Th0 immunity present during pregnancy has a decisive impact on shaping of the Th1 / Th2 T cell profile in the neonate. Furthermore, this effect favors the development of Th2 immune responses, when mice are exposed to a novel antigen during early childhood.