PERIPHERAL-BLOOD EOSINOPHILIA IN INFANTS AT 3 MONTHS OF AGE IS ASSOCIATED WITH SUBSEQUENT DEVELOPMENT OF ATOPIC DISEASE IN EARLY-CHILDHOOD

Background: We tested the hypothesis that eosinophilia in peripheral blood and nasal mucosa of infants is an early sign of allergic disease. Methods. The appearance of eosinophilic leukocytes in peripheral blood and nasal mucosa was studied prospectively in 67 infants up to 18 months of age, with or without a family history of atopy. Results: eosinophilia was associated with simultaneous presence or subsequent development of atopic disease at 3, 9, and 18 months of age, but not significantly so at 6 months. At 3 months children in whom atopic disease developed later during the observation period had significantly higher numbers of blood eosinophils than children without atopy (p < 0.01). Thus pronounced eosinophilia (> 7 x 10(8) cells/L) at that age was associated with moderate or severe allergic disease during the 18-month observation period. These children continued to have eosinophilia throughout the follow-up period. Blood eosinophilia at 3 months of age also correlated significantly to cord blood IgE levels and to skin prick test reactivity later during the follow-up period. Nasal eosinophilia was a common finding and therefore had little diagnostic or predictive value. Conclusions: Elevated eosinophil counts in peripheral blood of apparently healthy infants at 3 months of age is associated with a subsequent diagnosis of atopic disease.