The J43 monoclonal antibody specifically recognizes CD279 which is also known as PD-1 (programmed death-1). CD279 is a 50-55-kDa glycoprotein encoded by the Pdcd1 gene of the CD28 family of the Ig superfamily. The expression of Pdcd1 mRNA and PD-1 protein is tightly regulated. PD-1 is transiently expressed on CD4-CD8 thymocytes, it is upregulated on some cell lines upon induction of apoptosis, it is induced on thymocytes and splenic T and B lymphocytes after stimulation through their antigen receptors, and it is induced on activated myeloid cells. In addition, Pdcd1 mRNA is transiently expressed in developing B lymphocytes at the pro-B-cell stage. The presence of an ITIM (Immunoreceptor Tyrosine-based Inhibitory Motif) on PD-1's intracytoplasmic region and the development of splenomegaly and breakdown of peripheral tolerance in PD-1[-/-] mice suggest that PD-1 is involved in the negative regulation of immune responses. The PD-1 ligands, B7-H1 (also known as PD-L1, CD274) and B7-DC (PD-L2, CD273), are members of the B7 family of the Ig superfamily. The J43 antibody blocks the binding of PD-1 to its two ligands.
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).