Mannose receptor and its putative ligands in normal murine lymphoid and nonlymphoid organs: In situ expression of mannose receptor by selected macrophages, endothelial cells, perivascular microglia, and mesangial cells, but not dendritic cells.
The mannose receptor (MR) has established roles in macrophage (Mphi) phagocytosis of microorganisms and endocytic clearance of host-derived glycoproteins, and has recently been implicated in antigen capture by dendritic cells (DCs) in vitro. MR is the founder member of a family of homologous proteins, and its recognition properties differ according to its tissue of origin. Given this heterogeneity and our recent discovery of a soluble form of MR in mouse serum, we studied the sites of synthesis of MR mRNA and expression of MR protein in normal mouse tissues. We demonstrate that synthesis and expression occur at identical sites, and that mature Mphi and endothelium are heterogeneous with respect to MR expression, additionally describing MR on perivascular microglia and glomerular mesangial cells. However, MR was not detected on DCs in situ, or on marginal zone or subcapsular sinus Mphi, both of which have MR-like binding activities. We also compared expression of MR to the binding of a recombinant probe containing the cysteine-rich domain of MR. We show that MR and its putative ligand(s) are expressed at nonoverlapping sites within lymphoid organs, consistent with a transfer function for soluble MR. Therefore, in addition to endocytic and phagocytic roles, MR may play an important role in antigen recognition and transport within lymphoid organs.
Linehan
S A
SA
Sir William Dunn School of Pathology, Oxford OX1 3RE, United Kingdom.
Martínez-Pomares
L
L
Stahl
P D
PD
Gordon
S
S
D000818:Animals; D003713:Dendritic Cells / Q000276:immunology; D005786:Gene Expression Regulation / Q000276:immunology; D005920:Glomerular Mesangium / Q000378:metabolism; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D007668:Kidney / Q000378:metabolism; D037181:Lectins, C-Type; D008024:Ligands; D008221:Lymphoid Tissue / Q000378:metabolism*; D008264:Macrophages / Q000378:metabolism; D000090323:Mannose Receptor; D037241:Mannose-Binding Lectins; D051379:Mice; D008815:Mice, Inbred Strains; D017628:Microglia / Q000378:metabolism; D010587:Phagocytosis / Q000276:immunology; D012333:RNA, Messenger / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000235:genetics* / Q000378:metabolism; D012867:Skin / Q000378:metabolism; D013950:Thymus Gland / Q000378:metabolism
D037181:Lectins, C-Type; D008024:Ligands; D000090323:Mannose Receptor; D037241:Mannose-Binding Lectins; D012333:RNA, Messenger; D011956:Receptors, Cell Surface