[Assessment by flow cytometric method of IgE-binding state of basophils in allergic disorders]

Basophils, as well as mast cells, express Fc epsilon RI on the surface. It is known that activation of basophils and mast cells leads to induction of chronic allergic inflammation. In this study, levels of IgE bound to the surface of peripheral blood basophils were measured using a flowcytometry, and their clinical relevance was evaluated. Peripheral whole blood samples were stained with FITC-conjugated anti-IgE. The fluorescence intensity of the FITC-positive cells within mononuclear cell region was determined. Basophil-bound IgE levels increased along with age and reached invariably high levels of adults. The levels of basophil-bound IgE were higher among allergics than normal controls, in early infancy. In addition, many of the infants with repeated wheezing episodes also exhibited high levels of it. These findings suggest that early exposure of predisposed infants to antigens leads to early sensitization of circulating basophils. Basophil-bound IgE levels correlated well with serum IgE concentration, but they remained constant when IgE concentrations exceeded 300 ng/ml, suggesting that IgE-binding capacity of basophils become saturated at this IgE level. In conclusion, it is shown that flowcytometric measurement of basophil-bound IgE provides a useful method of analyzing this rare cell population within the peripheral circulation, and it serves as a critical parameter to evaluate the allergic inflammation in vivo.