Demonstration of intracytoplasmic IgE in circulating lymphocytes of allergic individuals

Cells containing intracytoplasmic IgE (IC IgE) were demonstrated in the peripheral blood mononuclear cells of atopic individuals by means of indirect immunofluorescence, employing mouse monoclonal anti-human IgE antibody. IC IgE-positive cells are low-density B cells as shown by centrifugation on discontinuous bovine serum albumin density gradient and by their reactivity with B1 monoclonal antibody specific to B lymphocytes, respectively. Further characterization of these cells by means of a rosette assay employing anti-Ig-coupled bovine erythrocytes indicated that these cells were surface IgE (sIgE) positive and sIgM negative. The data strongly suggest that activated IgE B cells are circulating in the blood of allergic individuals.