Effects of Combinations of Cytokines on Murine Antigen-Specific B Lymphocytes

Cytokines are among the most important mediators in the immune response. They act on B lymphocytes at various stages along the activation pathway. To study the effects of combinations of cytokines, we have used an antigen-specific single B cell-cloning system devised in this laboratory. We report here that IL-1 can enhance the proliferative response and IgM secretion by B cells induced by IL-6. The results of a similar study demonstrated that IL-1 can also enhance the effects of IL-5 on B cell proliferation and IgM secretion in an additive manner. Kinetic analyses showed that IL-1 had to be present from the beginning of the culture for an optimum cooperative effect, whereas the addition of IL-6 could be delayed up to 2 days without a significant reduction of the response. In contrast, IL-5 had to be added together with IL-1 at the onset of culture to promote an optimum response. The responses elicited by IL-1 plus IL-6, IL-1 plus IL-5, and IL-4 plus IL-5 were almost identical. The addition of further cytokines to these cultures gave no enhancement above the effects observed with the two-cytokine combinations.