Sialoadhesin (Sn) is a macrophage adhesion molecule containing 17 extracellular Immunoglobulin-like domains.
Sialoadhesin is an I-type lectin which binds to sialic acid ligands expressed on haematopoietic cells.
Other I-type lectins now termed Siglecs, include CD22 which is expressed on B-cells, myelin-associated glycoprotein (MAG) expressed on oligodendrocytes and Schwann cells and CD33 which is expressed on early myeloid cells and some monocytes.
Sialoadhesin is not expressed on all macrophages; expression is seen best on macrophages of the marginal zone in the spleen and the subcapsular sinus of lymph nodes. This section (Sn spleen) of a normal spleen stained with anti sialoadhesin MAb SER4 shows clearly the Sn staining only in macrophages of the marginal zone and no staining of macrophages in the white pulp areas (wp) or only weak staining of red pulp (rp) areas.
For more information about Sialoadhesin Contact Paul Crocker