Regulation of the human allergic response.

Over the last several years our laboratory has been engaged in the in vitro study of the regulation of IgE synthesis. We have found that polyclonal B cell activators fail to induce IgE synthesis in human B cells. Alloreactive T cell helper clones induced synthesis in B cells only under conditions of interaction and in B cells from allergic donors under cognate conditions of bystander stimulation as well. Isotype-specific regulation of the IgE response was mediated in the secretion of IgE-binding factors by T cells suppressing Fc receptors for IgE. Finally, IgE immune complexes in sera from patients with hyper-IgE states were shown to downregulate T cell proliferation to antigen and to stimulate monocytes to resorb 45Ca-labelled bone and to release prostaglandins. The implications of these in vitro findings for disease states in which IgE is elevated are discussed.