IgE+ cells in the peripheral blood of atopic, nonatopic, and bee venom-hypersensitive individuals exhibit the phenotype of highly differentiated B cells.

We have analyzed IgE+ cells in peripheral blood of atopic donors, donors hypersensitive to bee venom, and nonatopic control donors with two- and three-color flow cytometry. Although the percentage of IgE+ cells varied among these groups, the overall phenotypic patterns were similar. Most IgE+ cells do not display typical B-cell markers, such as CD19, CD20, and CD21. A significant proportion of these cells stain for CD38, indicating that they are more differentiated. IgE+ cells express Fc gamma RII and CD45RO, an isoform associated with an advanced level of differentiation. The majority of IgE+ cells do not coexpress other surface immunoglobulin isotypes. In the case of bee venom-hypersensitive donors, we have been able to identify a small population of IgE+ cells with a specificity for phospholipase A2, a major immunogenic component of bee venom. The phospholipase A2+ cells display a phenotype similar to that of the IgE+ cells.