The Epstein-Barr virus-induced production of IgE by human B cells.

B cells, isolated from the blood of healthy individuals and patients allergic to pollen, produced IgE when exposed to the human B-cell polyclonal activator, Epstein-Barr virus (EBV) in vitro and placed in culture. Secreted IgM and IgE were measured using immunoenzymatic assays. No difference was seen between healthy donors and allergic patients in the amount of IgE (or IgM) secreted. Cells were placed in limiting dilution cultures in order to determine the frequency of cells producing IgE or IgM (total and pollen specific) on exposure to EBV. Again, no significant differences in EBV-driven, B-cell precursor frequencies (PF) were seen between normal and allergic individuals. EBV-driven B-cell PF for total IgM and IgE, and pollen-specific IgM and IgE secretion, were 1/450, 1/6500, 1/83,000, and less than 1 per 2,500,000, respectively, for cells from healthy donors, and 1/140, 1/4000, 1/56,000 and less than or equal to 1 per 2,000,000, respectively, for cells from allergic patients. We propose that the increased IgE levels seen in atopic individuals result solely from regulatory defects, rather than an increase in the frequency of B cells committed to the secretion of IgE.