Age-dependent increase of IgE-binding and Fc epsilon RI expression on circulating basophils in children

Peripheral blood basophils are sparse in the circulation, but they express high-affinity receptors for IgE (Fc epsilon RI) and bind IgE efficiently. T he present study was performed to elucidate the role of IgE bound on the ba sophil surface in the development of allergic responses during infancy and early childhood. IgE-binding and Fc epsilon RI expression on basophils were evaluated by two-color flow cytometry. Basophil-bound IgE increased rapidl y and reached adult levels during infancy in atopic patients, while it grad ually increased with advancing age in parallel with serum IgE in normal con trols. IgE-binding and Fc epsilon RI expression in atopic children were hig her than in normal controls among various age groups. They correlated with serum IgE levels but reached a plateau when serum IgE exceeded 300 ng/mL. A low, but significant level of Fc epsilon RI expression was observed on cor d blood basophils, although IgE-binding was usually undetectable.