It is commonly assumed that aeroallergen sensitization in children persists. Two previous studies suggest that a proportion of school-age children spontaneously loose their sensitization. This phenomenon was examined further in younger children in a prospectively studied birth cohort.

The Childhood Allergy Study in suburban southeast Michigan was the source of these data. Testing for IgE to D. farinae, D. pteronyssinus, dog, cat, short ragweed, and timothy grass antigens was performed using a biotin-avidin amplified ELISA. Sensitization as determined by measurement of aeroallergen-specific circulating IgE to any of these 6 aeroallergens was assessed in children at ages 2 and 4 years.

Of the 339 children tested at ages 2 and 4 years, 165 initially had at least one positive allergen-specific IgE test. At age 4 years, 61 children (37%) who had had a positive test became negative to all tests upon retesting. 104 were positive and 109 were negative on both occasions. 65 of 174 (37%) who were initially negative, became positive.

Many children who were initially sensitized to an aeroallergen at age 2 years had lost their sensitization at age 4 years. This finding has significant implications for the longitudinal assessment of clinical allergy in young children as well as for the study of the immunological effects of allergen-injection immunotherapy.