Increased Expression of the Low-Affinity Receptor for IgE (FcεRII/CD23) on Rat Alveolar Macrophages

Abstract

The demonstration that various cell types can express a receptor for the Fc fragment of immunoglobulin E (IgE) (FcεRII/CD23) distinct from that described on mast cells and basophils (FcεRI), was obtained from the use of IgE-coated erythrocytes, binding studies with radiolabelled IgE, and more recently by the use of monoclonal anti-Fcε receptor antibodies (Dessaint and Capron 1988). The expression of this receptor is regulated by various cytokines and, as described recently, by lipid mediators such as platelet-activating factor (PAF) and leukotriene B₄ (LTB₄) (Dugas et al. 1989, 1990). Both murine and human lymphocytes and monocytes/macrophages express FcεRII/CD23 and secrete a soluble IgE-binding factor structurally related to this receptor (sCD23), two phenomena now known to play a major role in the regulation of the IgE synthesis (Pène et al. 1988; Delespesse et al. 1989). In the present review the possible relationship between FcεRII/CD23 expression on rat alveolar macrophages and the immunological reaction involved during the late phase reaction of allergic asthma are briefly described.