CYTOKINE CONTROL OF PERIPHERAL-BLOOD CD23 EXPRESSION AND SCD23 RELEASE - DIFFERENTIAL REGULATION BY IL-2 AND IL-4

CD23 expression on peripheral-blood lymphocytes (PBL) was studied under the influence of cytokines. It is shown that IL-2 induced CD23 expression on human peripheral-blood B cells. Evidence is presented that the IL-2 induced CD23 expression and release of soluble CD23 (sCD23) are not mediated by IL-4. In comparison to IL-4, the IL-2-induced CD23 expression and sCD23 release revealed kinetic differences and were not inhibited by anti-IL-4. The prestimulation of PBL with Staphylococcus aureus strains Cowan 1 (SAC) led to a pronounced reduction in basal CD23 expression and to a change in the response of cytokines. Subsequent stimulation with IL-4 induced CD23 to the same extent as on unstimulated cells, whereas the IL-2-induced CD23 expression and sCD23 release were greatly reduced. Interferon gamma showed no effects on the IL-4-stimulated CD23 expression of SAC-PBL, whereas the IL-2-induced CD23 expression was suppressed. Furthermore, we demonstrate that the stimulation with IL-2/IL-4 inhibits the effects of the individual cytokine; this inhibition is also seen for immunoglobulin (E, G, M) synthesis.