title: Expression and regulation of the orphan receptor RDC1 and its putative ligand in human dendritic and B cells.
abstract: Based on phylogenetic analysis and chromosomal mapping, the orphan receptor RDC1 was proposed to be a chemokine receptor. In this study we examined the expression of RDC1 on leukocytes by measuring mRNA levels and receptor expression using a new specific mAb. Both mRNA and protein levels were high in monocytes and B cells, relatively low on immature dendritic cells (DC), and up-regulated during final stages of maturation. Strikingly, in mature plasmacytoid DC the mRNA was up-regulated, but did not correlate with protein surface expression. We indeed report that CpG-activated plasmacytoid DC produce a putative ligand for RDC1, which selectively down-regulates RDC1, but not CXCR4 on primary human B cells. RDC1 expression was found to be tightly regulated during B cell development and differentiation. In blood-derived switch memory B cells, the expression of RDC1 appeared to correlate with the ability to differentiate into plasma cells upon activation, suggesting that RDC1 is a marker for memory B cells, which are competent to become Ab-secreting cells.
authors.affiliation: Institute for Research in Biomedicine, Bellinzona, Switzerland.
authors.forename: Simona
authors.initials: S
authors.lastname: Infantino
authors.forename: Barbara
authors.initials: B
authors.lastname: Moepps
authors.forename: Marcus
authors.initials: M
authors.lastname: Thelen
mesh_terms: D001402:B-Lymphocytes / Q000166:cytology / Q000276:immunology / Q000378:metabolism*; D002454:Cell Differentiation; D002478:Cells, Cultured; D054377:Chemokine CXCL12; D019743:Chemokines, CXC / Q000235:genetics / Q000378:metabolism; D003713:Dendritic Cells / Q000276:immunology / Q000378:metabolism*; D005786:Gene Expression Regulation; D006801:Humans; D008024:Ligands; D008221:Lymphoid Tissue / Q000378:metabolism; D054387:Receptors, CXCR; D043562:Receptors, G-Protein-Coupled / Q000235:genetics / Q000378:metabolism*
chemical_list: C501896:ACKR3 protein, human; C515255:CXCL12 protein, human; D054377:Chemokine CXCL12; D019743:Chemokines, CXC; D008024:Ligands; D054387:Receptors, CXCR; D043562:Receptors, G-Protein-Coupled