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 BUV615 which is part of the BD Horizon Brilliant™ Ultraviolet family of dyes. This dye is a tandem fluorochrome with an Ex Max near 350 nm and an Em Max near 615 nm. BD Horizon Brilliant BUV615 can be excited by the ultraviolet laser (355 nm) and detected with a 610/20 filter and a 595 nm LP. Due to the excitation of the acceptor dye by the blue/yellow-green laser line, there may be significant spillover into channels detecting PE-CF594 like emissions (eg, 610/20-nm filter).