Atopy parameters in asthmatic infants.

We evaluated various atopy parameters in 44 asthmatic infants aged 1-3 years: nonspecific parameters (total IgE and eosinophilia), and specific parameters relative to 21 allergens (specific IgE and skin tests), together with tests of leukotriene release by blood leukocytes (cellular allergen stimulation test; CAST) in the presence of a mixture of 21 allergens. Thus far 17 infants have displayed no sign of atopy, but 27 met at least one criterion. Eight met nonspecific criteria, and the others single or multiple criteria. Of the 21 allergens, 20 gave rise to at least one sensitization in this population. The specific IgE was more frequently positive than the skin tests. Dissociations between the two types of specific tests were practically systematic. Different phenotypes based on the chosen parameters were individualized, demonstrating heterogeneity in the expression of atopy in these young infants. The polyvalent CAST was positive only when other criteria of atopy were also positive (specific IgE and/or skin tests), and the range of intensity of the responses obtained supports reactivity rather than sensitization.