Synergistic augmentative effect of interleukin-10 and CD27/CD70 interactions on B-cell immunoglobulin synthesis

Interleukin-10 (IL-10) is a potent cytokine that regulates immunoglobulin synthesis by B cells. CD27/CD70 interactions by direct cell-to-cell contact are also needed to produce substantial amounts of immunoglobulin. We have investigated the effects of IL-10 and CD27/CD70 interactions on the immunoglobulin synthesis. In the presence of IL-10 stimulation, the production of IgG, IgM and IgA was increased synergistically by the addition of CD27 ligand (CD70)-transfectants in a dose-dependent manner, which was completely blocked by anti-CD70 monoclonal antibody. In contrast, CD70-transfectants additively enhanced the immunoglobulin production in the presence of IL-2, IL-4, or IL-6. The synergistic enhancement of the immunoglobulin production by IL-10 and CD70-transfectants was remarkable in highly purified CD27+ B cells, but there was no immunoglobulin production in CD27- B cells. Furthermore, by the addition of CD70-transfectants, the synthesis of IgG1, IgG2, IgG3 and IgG4 was also enhanced in the presence of IL-10. On the other hand, IL-10 diminished CD27 expression in B cells. B-cell proliferation was augmented by CD70-transfectants with IL-10 or IL-10 plus IL-2. The addition of IL-2 further augmented the immunoglobulin production which was synergistically enhanced by IL-10 and CD27 triggering. Taken together, the co-operative response to IL-10 and CD27/CD70 interactions regulates B-cell immunoglobulin production.