The identity of IgE receptors (Fc epsilon RII) that mediate cellular activation of human macrophages: evidence against a role for CD23.

There is now compelling evidence that macrophages bind IgE, and are involved in several IgE-dependent responses. The CD23 antigen mediates a mitogenic response in "primed" B-lymphocytes, although its expression is not confined to B cells, and CD23 is inducably expressed in many cells including macrophages. CD23 is also known to bind IgE, a property that leads to inhibition of the mitogenic response in B cells. In the present review, the possibility that CD23 mediates IgE-dependent responses in macrophages has been re-examined, and it is proposed that the functional receptor for IgE on macrophages may be quite separate from the CD23 antigen.