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™ BV711 which is part of the BD Horizon Brilliant™ Violet family of dyes. This dye is a tandem fluorochrome of BD Horizon BV421 with an Ex Max of 405-nm and an acceptor dye with an Em Max at 711-nm. BD Horizon BV711 can be excited by the violet laser and detected in a filter used to detect Cy™5.5 / Alexa Fluor® 700-like dyes (eg, 712/20-nm filter). Due to the excitation and emission characteristics of the acceptor dye, there may be moderate spillover into the Alexa Fluor® 700 and PerCP-Cy5.5 detectors. However, the spillover can be corrected through compensation as with any other dye combination.