Effects of winter birth season and prenatal cockroach and mouse allergen exposure on indoor allergen-specific cord blood mononuclear cell proliferation and cytokine production.

BACKGROUND Season of birth has been associated with the development of atopy and asthma. Relationships among a particular birth season, maternal allergen exposure during the birth season, and childhood development of allergies to allergens in higher concentration during the birth season may be important. OBJECTIVE To investigate the effects of winter birth (January 1 to March 31) and prenatal cockroach and mouse allergens in settled dust on indoor allergen-specific cord blood mononuclear cell (CBMC) proliferation, TH2 production, and cord blood IgE concentration. METHODS As part of an ongoing prospective study, 350 cord blood samples were collected. The CBMCs were cultured with cockroach, dust mite, and mouse protein extracts, and proliferation was measured. Interleukin 5, interferon-delta, and total IgE levels were measured. Home dust samples were analyzed for cockroach and mouse allergens. RESULTS An isolated association was observed between winter birth and a greater mean (SD) cockroach interleukin 5 ratio (winter vs nonwinter birth: 26,043 [11,403] vs 11,344 [3,701]; P = .02). Other associations between winter birth and increased CBMC proliferation, T-helper cytokines, or cord blood IgE levels were not detected. Higher mouse allergen levels were associated with decreased mouse-induced proliferation (winter vs nonwinter birth: mean [SD] stimulation index, 1.72 [0.12] vs 2.02 [0.11]; P = .04). CONCLUSIONS Winter birth and increased cockroach or mouse allergen levels during pregnancy were not consistently associated with greater CBMC proliferation, T-helper cytokine production, or cord blood IgE levels. Greater indoor allergen exposure during pregnancy does not seem to affect the development of cockroach or mouse immune responses in utero.