Inhibition of an in vivo antigen-specific IgE response by antibodies to CD23.

Immunoglobulin E (IgE) mediates many allergic responses. CD23 is a 45-kilodalton type II transmembrane glycoprotein expressed in many cell types. It is a low-affinity IgE receptor and interacts specifically with CD21, thereby modulating IgE production by B lymphocytes in vitro. In an in vivo model of an allergen-specific IgE response, administration of a rabbit polyclonal antibody to recombinant human truncated CD23 resulted in up to 90 percent inhibition of ovalbumin-specific IgE synthesis. Both Fabs and intact IgG inhibited IgE production in vitro and in vivo. Thus, CD23 participates in the regulation of IgE synthesis in vivo and so could be important in allergic disease.