Expression of CC chemokine receptor 3 on human keratinocytes in vivo and in vitro - upregulation by RANTES

CC chemokines and their ligands, CC chemokine receptors (CCRs), play an important role in the process of inflammation such as trafficking and activating inflammatory cells. CCR3 is known to be a ligand for CC chemokines such as RANTES, eotaxin and monocyte-chemotactic protein-3 (MCP-3). In this study we examined the expression of CCR3 in cultured normal human keratinocytes (KCs). CCR3 protein and mRNA expressions were detected in cultured normal KCs by flow cytometric (FACS) analysis and reverse-transcription-polymerase chain reaction (RT-PCR) analysis. FACS analysis demonstrated that CCR3 expression on KCs was significantly upregulated when the cells were cultured with RANTES, but not with eotaxin, IL-4 or interferon-γ. RT-PCR analysis revealed that CCR3 mRNA was detectable in normal KCs. We also examined the immunoreactivity of CCR3 in normal skin and inflammatory skin lesions. CCR3 was detected weakly in epidermis of normal skin, while strong immunoreactivity for CCR3 was seen in epidermis of inflammatory skin lesions such as atopic dermatitis. These results suggest that CCR3 is constitutively expressed on KCs and is involved in inflammatory modulation. RANTES may regulate the function of KCs through CCR3.