title: The interplay of interleukin-10 (IL-10) and interleukin-2 (IL-2) in humoral immune responses: IL-10 synergizes with IL-2 to enhance responses of human B lymphocytes in a mechanism which is different from upregulation of CD25 expression.
abstract: The role of the interplay of interleukin-2 (IL-2) and interleukin-10 (IL-10) in responses of human peripheral blood B cells stimulated by ligation of antigen receptors was examined in detail. Highly purified peripheral blood B cells from normal human individuals were cultured with Staphylococcus aureus Cowan I (SA) in the presence or absence of IL-10 and IL-2. Although IL-10 alone could modestly induce Ig production by SA-activated B cells, IL-10 markedly enhanced the Ig production in synergism with IL-2. This synergistic effect between IL-2 and IL-10 was completely abrogated by addition of either anti-CD25 mAb or anti-IL-10 mAb, indicating signals through high-affinity IL-2 receptors are involved in the synergism. In fact, IL-10 upregulated the expression of alpha-chain of IL-2 receptors (CD25) on B cells stimulated by SA alone or SA + IL-2 for 72 hr. However, such upregulation of CD25 expression did not result in significant enhancement of subsequent responses of the activated B cells to IL-2. Of note, during the initial activation phase of B cells, IL-2 was much more effective than IL-10 in enhancing the subsequent responses to either IL-2 or IL-10. By contrast, IL-10 was much more effective than IL-2 in supporting the maturation of B cells following the initial activation. Finally, the synergy between IL-2 and IL-10 was not observed in the initial activation phase, but in the subsequent maturation phase of activated B cells. These results indicate that IL-10 and IL-2 synergistically enhance Ig production of SA-activated B cells in a mechanism which is different from the upregulation of IL-2 receptors. Moreover, the data emphasize the importance of the interplay of IL-2 and IL-10 in determining the outcome of humoral immune responses.
authors.affiliation: 2nd Department of Internal Medicine, Teikyo University School of Medicine, Tokyo, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Itoh
authors.forename: T
authors.initials: T
authors.lastname: Inoue
authors.forename: K
authors.initials: K
authors.lastname: Ito
authors.forename: S
authors.initials: S
authors.lastname: Hirohata
mesh_terms: D000328:Adult; D000917:Antibody Formation / Q000187:drug effects; D001402:B-Lymphocytes / Q000166:cytology / Q000276:immunology*; D002454:Cell Differentiation; D002478:Cells, Cultured; D004357:Drug Synergism; D006801:Humans; D007074:Immunoglobulin G / Q000096:biosynthesis; D007075:Immunoglobulin M / Q000096:biosynthesis; D066298:In Vitro Techniques; D016753:Interleukin-10 / Q000008:administration & dosage*; D007376:Interleukin-2 / Q000008:administration & dosage*; D015375:Receptors, Interleukin-2 / Q000502:physiology; D013211:Staphylococcus aureus / Q000276:immunology; D015854:Up-Regulation
chemical_list: D007074:Immunoglobulin G; D007075:Immunoglobulin M; D007376:Interleukin-2; D015375:Receptors, Interleukin-2; D016753:Interleukin-10