The OX-119 monoclonal antibody specifically recognizes Signal-regulatory protein gamma (SIRP-gamma or SIRPγ) which is also known as CD172g or Signal-regulatory protein beta 2 (SIRP-beta-2 or SIRPβ2). SIRPγ (CD172g) is a ~55 kDa type I transmembrane glycoprotein that is encoded by SIRPG, which belongs to the SIRPβ2 subfamily within the Ig gene superfamily. The SIRPγ (CD172g) extracellular domain contains one amino-terminal IgV-like domain and two IgC-like domains, and a short cytoplasmic region with no known motifs. It is expressed on mature thymocytes, CD4+ T-cells, CD8+ T-cells, CD56-bright natural killer (NK) cells, all activated NK cells and some B cells. SIRPγ (CD172g) binds to CD47 (integrin-associated protein/IAP) that is widely expressed on most hematopoietic cells, epithelial cells, endothelial cells, fibroblasts and many tumor cell lines. SIRPγ (CD172g) may play a regulatory role in T cell-T cell interactions and may induce apoptosis through CD47.
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).