Interleukin 4 dependent induction of IgE synthesis and CD23 expression by the supernatants of a human helper T cell clone.

The supernatants of the human alloreactive helper T cell clone A1, which secretes interleukins (IL) 4 and 5, could induce IgE synthesis by normal peripheral blood mononuclear cell and expression of Fc epsilon R2/CD23 on normal human monocytes. Both effects were IL-4 dependent, since they could be induced by recombinant IL-4 alone and were inhibited by an anti-IL-4 antibody. The activation of such clones may contribute to the high IgE production and the high percentage of circulating CD23+ monocytes observed in allergic disorders.