The effects of interleukins 4 and 5 on the differentiation of B cells from (NZB x NZW)F1 mice.

We describe here that IL-4 and IL-5 together can induce the production of high amounts of IgG1 polyclonal antibodies by B cells from old (NZB x NZW)F1 mice even in the absence of LPS. The effect was less marked in young mice from the same strain or in normal Balb/c mice. The cells sensitive to the treatment with the interleukins were the large B cells. Old mice had higher proportions of such cells than young mice or normal Balb/c mice. Synthesis of anti-DNA antibodies of the IgM class was induced. Although IL-4 plus IL-5 induced a strong polyclonal IgG1 production, there were no IgG1 anti-DNA antibodies.