Phorbol ester enhances both interleukin 2 receptor expression and immunoglobulin secretion in human Epstein-Barr virus-immortalized B cells.

The enhanced expression of interleukin 2 (IL2) receptors by 12-O-tetradecanoylphorbol 13-acetate (TPA) on sublines of an Epstein-Barr virus-immortalized human B17 B cell line (M. Steinitz et al., Immunobiology 1979. 156: 41.) was studied by immunofluorescence using the anti-Tac monoclonal antibody and by binding studies with purified radiolabeled IL2. These studies show that TPA at a final concentration of 5 ng/ml greatly increased Tac antigen expression on a number of sublines of B17. IL2-binding studies revealed that TPA induced an increase in not only the number of IL2 receptors per cell but also the affinity of the receptors for IL2. The number and affinity of IL2 receptors on the C76 subline treated with TPA appear to be similar to those of activated normal human peripheral T cells. Furthermore, TPA-induced differentiation of these B cell lines was measured by induction of immunoglobulin secretion using an enzyme-linked immunosorbent assay. The capacity of TPA to induce differentiation in human B cells and the biological significance of IL2 receptor expression by activated B cells are discussed.