Allergic sensitization and allergen exposure during pregnancy favor the development of atopy in the neonate

Background: Several studies have considered that the in utero environment p lays an important role in the onset of the allergic phenotype. We assessed whether allergic sensitization and allergen exposure during pregnancy favor the postnatal onset of allergy in the neonate. Methods: BALB/c mice were s ensitized to ovalbumin (OVA) before mating followed by allergen aerosol exp osure during pregnancy. T and B cell responses in offspring were followed u p until day 60 postpartum. At the age of 4 weeks offspring were exposed to a heterologous antigen, P-lactoglobulin (BLG). Results: Pregnant mice devel oped immediate hypersensitivity responses and Th-2/Th-0 immunity following allergen aerosol exposure. At birth, T cells from offspring of nonsensitize d BALB/c mice were characterized by an impaired IFN-gamma production, which was lowered even further in offspring of OVA-sensitized BALB/c mice. Offsp ring of OVA-sensitized BALB/c mice responded with immediate-type cutaneous hypersensitivity reactions to OVA which could be related to the pre- and po stnatal transfer of maternal OVA-specific IgG1 antibodies. After exposure t o BLG, offspring of OVA-sensitized BALB/c mice developed an accelerated Th- 2-driven immune response compared to offspring from nonsensitized BALB/c mi ce as indicated by enhanced anti-BLG IgG1 antibody production and increased numbers of positive immediate-type cutaneous hypersensitivity reactions to BLG. Conclusion: Our data suggest that Th-2/Th-0 immunity present during p regnancy has a decisive impact on shaping the Th-1/Th-2 T cell profile in r esponse to postnatal allergen exposure. Copyright (C) 2001 S. Karger AG. Ba sel.