Human recombinant erythropoietin directly stimulates B cell immunoglobulin production and proliferation in serum‐free medium

Abstract

The effect of human recombinant erythropoietin (Epo) on B cell responses was studied in a serum‐free medium. Epo enhanced IgM production and thymidine uptake by a human IgM‐producing lymphoblasloid cell line, CBL. This effect was specific to Epo since enhancement was blocked by anti‐Epo antibody but not by control antibody. Among the various cytokines, interleukin‐4 (IL‐4) enhanced IgM production and thymidine uptake while IL‐6 enhanced IgM production without affecting thymidine uptake. In contrast, other cytokines including IL‐1β, IL‐2, IL‐5, interferon‐alpha (IFN‐α), interferon‐gamma (IFN‐γ), or granulocyte/macrophage colony‐stimulating factor (GM‐CSF) were without effect. However, the enhancing effect of Epo is different from that of IL‐4 or IL‐6, since Epo effect was not blocked by anti‐IL‐4 antibody or anti‐IL‐6 antibody. Moreover, specific binding of Epo was detected on CBL cells. Epo also enhanced immunoglobulin (IgG, IgM and IgA) production and thymidine uptake by purified tonsil small resting B cells stimulated by Staphylococcus aureus Cowan strain I (SAC) or by large activated B cells. In contrast, Epo had no effect on unstimulated smalt resting B cells. These results indicate that Epo could directly stimulate activated and differentiated B cells and could enhance B cell immunoglobulin production and proliferation. Copyright © 1991, Wiley Blackwell. All rights reserved