Little is known about the immunologic maturation in the early stages of life. The aim of this study was to investigate maturation of immune system from birth to 1 yr of age and to compare immune functions between mothers and their children. Also the effect of atopy to the immune responses of children was examined. Cord blood samples (n = 228) and peripheral blood samples of children (n = 200) and their mothers (n = 208) 1 yr after birth were collected. Whole blood samples were stimulated for 24 and 48 h with Staphylococcal enterotoxin B (SEB), lipopolysaccharide (LPS) and the combination of phorbol ester and ionomycin (P/I). Production of TNF-alpha, IFN-gamma, IL-5, IL-8 and IL-10 was determined using ELISA. Significant mother-to-child correlation was detected in cytokine-producing capacity at the age of 1 yr. TNF-alpha (P/I, SEB and LPS stimulation), IFN-gamma (P/I and SEB), IL-5 (P/I and SEB) and IL-10 (P/I, SEB and LPS) producing capacity increased from birth to 1 yr of age. In general, stimulated cytokine responses were higher in mothers' than in children's blood samples, except in the case of P/I and LPS-stimulated IL-8, which were highest at birth. Maternal inhalation atopy was associated with increased cord blood IL-5 (24 and 48 h) and IL-10 (48 h) production following P/I stimulation. Also children of food atopic mothers expressed elevated cord blood IL-10 (48 h, P/I) responses and decreased IFN-gamma/IL-5 ratio (24 h, P/I). In addition, the production of IFN-gamma (24 and 48 h, P/I) and the IFN-gamma/IL-5 ratio (24 h and 48 h, P/I) at the age of 1 yr was lower among children with food atopic mothers. In conclusion, our results suggest that both adaptive and innate immune responses increase from birth to 1 yr of age, but are still weak in comparison to adult responses. Cytokine responses of children begin to correlate with those of their mothers during the first year of life. Although only few associations were observed between atopy and cytokine-producing capacity, our results suggest that children of atopic mothers express T(h)2-polarized cytokine pattern.

Exposure to Gram-negative bacteria and their components may be associated with down-regulated immune responses in early infancy, indicated as an impaired production of pro-inflammatory cytokines following mitogen stimulation. Gram-positive bacteria and their constituents seem to have opposite effects. Of the measured markers, exposure to bioactive endotoxin appears to have the strongest impact on T-helper type 1 responses.

Having a dog in the household in infancy and already during pregnancy may be associated with reduced innate immune responses in early childhood. The observed attenuation of cytokine production may help in preventing exaggerated immune responses against harmless antigens later in life. Thus, intensive exposure to dogs in early life may be beneficial during normal immune maturation.

Environmental exposure to pollen and ultraviolet irradiation during gestation may have an effect on the cytokine profile of the offspring in CB because children born in the spring or winter showed the lowest IL-5, IL-10 and IFN-γ responses. The production of IL-10 and IFN-γ was also inversely associated with prostaglandin labour induction before birth. Other labour-related factors were not significantly associated with production of IL-5, IL-10 and IFN-γ after WBC count correction.

Background: Exposure to microbes and their components may affect the maturation of the immune system.We examined the association of house dust microbial content with cytokine-producing capacity at birth and at the age of 1 year. Methods: Production of TNF-α, IFN-γ, IL-5, IL-8 and IL-10 at birth (n = 228) and at the age of 1 year (n = 200) following 24- and 48-hour whole-blood stimulation with staphylococcal enterotoxin B (SEB), lipopolysaccharide and the combination of phorbol ester and ionomycin was measured. Concentrations of ergosterol (marker for fungal biomass), muramic acid (marker for Gram-positive bacteria) and 3-hydroxy fatty acids with a carbon chain length from 10 to 14 (marker for Gram-negative bacteria) in living room floor dust were analyzed using gas chromatography-tandem mass spectrometry. Five single microbial species or groups were determined using a quantitative polymerase chain reaction method. Results: A high total level of the studied Gram-positive bacteria in general or Mycobacterium spp. in house dust was associated with decreased SEB-stimulated IFN-γ production, especially at the age of 1 year. The total level of indoor fungi analyzed (Penicillium spp., Aspergillus spp. and Paecilomyces variotii group, Trichoderma viride/atroviride/koningii,Wallemia sebi) was also inversely associated with IFN-γ production at the age of 1 year, but this association did not remain significant after adjustment for potential confounders. A few associations were found between microbial exposures and other measured cytokines. Conclusions: High indoor microbial exposures may affect immune development in early life by reducing T helper type 1 cytokine secretion capacity. The observed hyporesponsiveness may reflect the adaptation of the immune system to environmental antigens. In future, more attention should be paid especially to the immunomodulatory role of exposures to Gram-positive bacteria.