The RMP1-30 monoclonal antibody specifically recognizes CD279 which is also known as PD-1 (programmed death-1). CD279 (PD-1) is a ~55 kDa type I transmembrane glycoprotein that is encoded by Pdcd1 which belongs to the CD28/CTLA-4 family within the Ig superfamily. CD279 (PD-1) is comprised of an extracellular region with an IgV-like domain and an intracellular region with an immunoreceptor tyrosine-based inhibitory motif (ITIM) and an immunoreceptor tyrosine-based switch motif (ITSM) that are associated with inhibitory signaling functions. CD279 (PD-1) is transiently expressed on CD4-CD8- thymocytes and developing B lymphocytes at the pro-B-cell stage. It is also expressed on activated myeloid cells, B cells, and T cells including exhausted T cells found in mice during chronic viral infections or cancer. This co-inhibitory receptor reportedly functions in negative regulation of immune responses and thus helps guard against autoimmunity and preserves peripheral tolerance. CD273 (also known as PD-L2 or B7-DC) and CD274 (PD-L1 or B7-H1) are members of the B7 family within the Ig superfamily that serve as ligands for CD279 (PD-1). The RMP1-30 antibody reportedly does not block the binding of CD279 (PD-1) to these ligands.
The antibody was conjugated to BD Horizon™ BUV737 which is part of the BD Horizon Brilliant™ Ultraviolet family of dyes. This dye is a tandem fluorochrome of BD Horizon BUV395 with an Ex Max of 348-nm and an acceptor dye with an Em Max at 737-nm. BD Horizon Brilliant BUV737 can be excited by the ultraviolet laser (355 nm) and detected with a 740/35 filter. Due to the excitation of the acceptor dye by other laser lines, there may be significant spillover into channels detecting Alexa Fluor® 700-like dyes (eg, 712/20-nm filter).
Due to spectral differences between labeled cells and beads, using BD™ CompBeads can result in incorrect spillover values when used with BD Horizon BUV737 reagents. Therefore, the use of BD CompBeads or BD CompBeads Plus to determine spillover values for these reagents is not recommended. Different BUV737 reagents (eg, CD4 vs. CD45) can have slightly different fluorescence spillover therefore, it may also be necessary to use clone specific compensation controls when using these reagents.