The 7-239 monoclonal antibody specifically binds to Sialic acid-binding Ig-like lectin 1 (Siglec-1), which is also known as Sialoadhesin (SN), or CD169. Siglec-1 is a type I transmembrane glycoprotein that belongs to the Siglec family within the Ig superfamily. This adhesion molecule especially binds to glycolipids and glycoproteins with terminal α-2 sialyl residues. Siglec-1 is expressed by macrophages and dendritic cells and serves as a cellular interaction molecule. Its expression can be upregulated by cells in response to type II collagen, or to cytokines including interferons, and tumor necrosis factor. Siglec-1 plays roles in endocytosis, hematopoiesis, and leucocyte migration. It mediates macrophage binding to various cell types including developing and mature leucocytes. Siglec-1 that is expressed by dendritic cells can also bind HIV-1 and may mediate viral transfer to bystander CD4+ T cells. Several Siglec-1 counter-receptors have been described including CD43, CD206, and CD227 which are expressed by T cells, macrophages, or breast cancer cells, respectively. The 7-239 antibody reportedly blocks Siglec-1 functions in some cellular assay systems.
The antibody was conjugated to BD Horizon Red 718, which has been developed exclusively for BD Biosciences as a better alternative to Alexa Fluor® 700. BD Horizon Red 718 can be excited by the red laser (628 – 640 nm) and, with an Em Max around 718 nm, it can be detected using a 730/45 nm filter. Due to similar excitation and emission properties, we do not recommend using R718 in combination with APC-R700 or Alexa Fluor® 700.