Quantitative and qualitative estimations of IgE bound to basophil leukocytes from hay fever patients

IgE was removed from human basophils of 4 nonatopic persons and 10 hay fever patients allergic to timothy grass pollen by treating the cells with buffer adjusted to pH 4. IgE could be removed and refixed to the same cells. Refixation was demonstrated by immunofluorescence and by the ability of basophils to release histamine on exposure to timothy pollen. Removed total IgE and specific IgE directed against timothy pollen were estimated, and a linear correlation to the level of total IgE and specific IgE in serum was found. The total number of IgE molecules per basophil was calculated to be in the range of 30,000 to 300,000, and timothy-specific IgE constituted 4%-15% of the total IgE molecules on the cells. It was furthermore established that specific cell-bound IgE was linearly correlated to the pollen concentration releasing 20% of the histamine contents of the basophils. Separated 2gE from sensitized and nonsensitized basophils could be bound to basophils from other patients, resulting in a change in cell sensitivity. This could be ascribed to additional binding to free cell receptors as well as to a partial replacement of bound IgE. Basophils from non-atopic persons could not be sensitized by incubation with surface IgE from atopic persons. The results indicate that acid treatment is a simple method suitable for removing IgE from basophils. This IgE is intact and can be quantitated.