Umbilical cord blood mononuclear cell proliferative response to house dustmite does not predict the development of allergic rhinitis and asthma

Background: Cord blood mononuclear cells (CBMNCs) have been found to prolif erate when stimulated with food or inhalant allergens. The significance of this finding is not known. Objectives: We sought to determine the factors associated with proliferatio n of CBMNCs when stimulated with house dust mite (HDM) allergen and to dete rmine whether proliferation of CBMNCs is associated with subsequent develop ment of HDM sensitization and development of allergic rhinitis and asthma. Methods: Cord blood was taken from infants at high risk for having asthma a nd allergic diseases who were recruited for a primary prevention study in w hich infants were randomized into the intervention or the control group. CB MNCs were stimulated with HDM allergen and PAA as a positive control. Infan ts were assessed at 12 and 24 months for health outcome. Results: When stimulated with HDM allergen, 29.7% of infants had a stimulat ion index (SI) of 2 or greater. There were no differences in the levels of cord blood IgE and cotinine, maternal smoking, immediate skin test reactivi ty, maternal IgE, and maternal exposure to HDM allergen between those with an SI of 2 or greater and those with an SI of less than 2. Infants with an SI of less than 2 had a significantly higher proportion of mothers with a h istory of asthma. No differences in the incidence of "asthma" and rhinitis without cold at 12 months and cumulative prevalence at 24 months were seen between the 2 groups. None of the infants had skin test reactions to ADM al lergen. Conclusion: The negative association between HDM allergen-induced prolifera tion of CBMNCs and maternal mite allergen exposure and health outcomes at 1 2 and 24 months raises the issue of the significance of CBMNC proliferation .