Interferon-γ induces light chain synthesis in interleukin 2 stimulated human B cells

Abstract

Human B cells were cultured without added lymphokines, with interleukin 2 (IL 2) or interferon-γ (IFN-γ) alone, or with a combination of IL2 and IFN-γ. Treatment with IL2 alone induced differentiation of the B cells, as shown by an increase in the number of immunoglobulin (Ig)-containing cells and plaque-forming cells, and by a larger amount of Ig secreted into the medium. In most of the induced Ig-containing cells, heavy chains but not light chains were detectable by cytoplasmic staining. Treatment with IFN-γ alone did not stimulate B cell differentiation. However, a combination of IFN-γ and IL2 was more effective than IL 2 alone in inducing B cell differentiation, as measured by further increases in the number of plaque-forming cells and in total Ig secretion. Furthermore, after treatment with both 1L 2 and IFN-γ, most cells that contained cytoplasmic heavy chains also contained cytoplasmic light chains. We conclude that IFN-γ acts in synergy with IL2 in B cell differentiation by enhancing light chain synthesis, leading to secretion of Ig molecules.