REGULATION OF CD23 EXPRESSION BY IL-4 AND CORTICOSTEROID IN HUMAN B-LYMPHOCYTES - ALTERED RESPONSE AFTER EBV INFECTION

Cellular CD23 has been implicated in various biologic and pathologic p rocesses. Here, we have studied the regulation of B cell CD23 expressi on and function by the synthetic corticosteroid, dexamethasone (DEX). We report that DEX acts directly on B lymphocytes to down-regulate IL- 4-induced CD23 expression, whereas in parallel the IL-4R is up-regulat ed. Down-regulation of CD23 occurred at the cell surface and for shed material in culture medium. EBV infection of B cells is linked to deve lopment of lymphoproliferative diseases, including lymphoma, and there is evidence that EBV-stimulated CD23 expression may be instrumental i n the inappropriate survival of infected cells. We have determined tha t treatment of EBV-infected cells with IL-4 leads to a synergistic up- regulation of B cell CD23. Furthermore, infection of B cells by EBV in troduced a relative resistance to the down-regulatory effects of DEX o n IL-4-induced CD23 expression.