Regulation of chemokine receptor expression in eosinophils

Signals via chemokine receptors play an important role in the accumulation of eosinophils at allergic inflammatory sites. Eosinophils constitutively e xpress CC chemokine receptor 3 (CCR3) and, to a lesser extent, CCR1. CCR3 i s mainly responsible for migration of resting eosinophils, and its specific ligand, eotaxin, represents the most potent chemoattractant for eosinophil s. Some reports also suggest the expression of CXC chemokine receptor 1 (CX CR1) and/or CXCR2 in eosinophils. in addition, we recently reported the fun ctional expression of CXCR4. The ligand of CXCR4, stromal cell-derived fact or-1 (SDF-1), was able to induce a strong migratory response comparable to that by eotaxin. In contrast to the CCR3/eotaxin system which is mainly reg ulated at the level of ligand production, the CXCR4/SDF-1 system is regulat ed at the level of receptor expression. CXCR4 expression was completely att enuated by IL-4 and IL-5 and upregulated by IFN-gamma and dexamethasone, wh ile CCR3 expression was only marginally affected. The balance between the b iological effects of these chemokine systems may affect the distribution an d migration of eosinophils. Copyright (C) 2001 S. Karger AG, Basel.