The 7B11 (also known as CMSSC-7B11) monoclonal antibody specifically binds to human GARP (Glycoprotein A repetitions predominant). The LRRC32 (Leucine rich repeat containing 32) gene encodes the 662 amino acid-residue, 80 kDa transmembrane GARP glycoprotein that has an extracellular region composed primarily of 20 leucine-rich repeats. GARP is specifically expressed on Treg cells activated through the T cell receptor (TCR). Ectopic expression of GARP in human naïve T cells inhibited their proliferation and cytokine secretion upon TCR activation. Remarkably, GARP over-expression in naïve T cells induced expression of FoxP3 and endowed them with a partial suppressive function. The extracellular, but not the cytoplasmic region, of GARP was necessary for these functions. GARP serves as a receptor for latent TGF-beta which may play a role in the suppressive action of Treg cells. GARP is also expressed on platelets and other tissues, however the function on these cells is not known.
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).