Fig. 4
From: Neutrophil chemoattractant receptors in health and disease: double-edged swords
Regulation of chemokine receptor expression by neutrophils. Naive neutrophils, freshly released from the bone marrow, display high levels of CXCR1 and CXCR2, which are the two major chemokine receptors involved in the trafficking of human neutrophils. Exposure to endogenous or exogenous inflammatory mediators may induce the upregulation of additional chemokine receptors, e.g., CCRs and CXCR3. Prolonged stimulation or exposure to high chemokine concentrations induces the downregulation of chemokine receptors. Consequently, highly activated, infiltrated cells are characterized by low CXCR1 and CXCR2 expression levels. Neutrophil aging is accompanied by the upregulation of CXCR4 expression, thereby facilitating a return of the cell to the bone marrow, which contains high levels of CXCL12
