Ultrastructural localisation of sialoadhesin (siglec-1) on macrophages in rodent lymphoid tissues.
In previous studies it has been demonstrated that sialoadhesin is a macrophage-restricted adhesion receptor for lymphocytes and myeloid cells. It is under normal circumstances expressed by subpopulations of macrophages in lymphoid and haemopoietic tissues. In this study different immunoelectronmicroscopical techniques are used to investigate the ultrastructural localisation of sialoadhesin within the lymph node and spleen of rodents. The results show that sialoadhesin is selectively expressed by a subset of macrophages in peripheral lymphoid tissues. Sialoadhesin was localised predominantly on the plasma membrane and in particular in areas of intimate contact with lymphocytes, thereby visualizing putative local interaction between these cells. Interestingly, sialoadhesin was also detected in intracellular vesicles that were apparently taken up by macrophages. These findings are consistent with the putative role of sialoadhesin in local cell-cell interactions in lymphoid tissues. Surprisingly, sialoadhesin was also found at contact points of macrophages with other macrophages, sinus-lining cells and reticulum cells, suggesting that sialoadhesin also mediates interactions with these cell types.
Schadee-Eestermans
I L
IL
Dept. of Cell Biology and Immunology, Faculty of Medicine, Vrije Universiteit, Amsterdam, The Netherlands. IL.Schadee_Eestermans.cell@med.vu.nl
Hoefsmit
E C
EC
van de Ende
M
M
Crocker
P R
PR
van den Berg
T K
TK
Dijkstra
C D
CD
D000818:Animals; D015815:Cell Adhesion Molecules / Q000032:analysis*; D002462:Cell Membrane / Q000737:chemistry; D008221:Lymphoid Tissue / Q000166:cytology; D008264:Macrophages / Q000737:chemistry* / Q000648:ultrastructure; D008297:Male; D008562:Membrane Glycoproteins / Q000032:analysis*; D051379:Mice; D051381:Rats; D017208:Rats, Wistar; D011971:Receptors, Immunologic / Q000032:analysis*; D063267:Sialic Acid Binding Ig-like Lectin 1
D015815:Cell Adhesion Molecules; D008562:Membrane Glycoproteins; D011971:Receptors, Immunologic; D063267:Sialic Acid Binding Ig-like Lectin 1; C571167:Siglec1 protein, mouse