The L272 monoclonal antibody specifically recognizes CD26 which is also known as Dipeptidyl peptidase IV (DPP IV), a serine protease. CD26 is a ~120 kDa type II transmembrane glycoprotein that is encoded by DPP4 and belongs to the DPP4 activity and/or structure homologue (DASH) protein family. It is associated with the binding of the TAT transactivating protein of the HIV. CD26 and CD45 act in a costimulatory fashion on T lymphocytes. Present on peripheral blood T lymphocytes, the CD26 antigen is upregulated on phytohemagglutinin (PHA) and concanavalin A (Con A)-stimulated peripheral blood mononuclear cells (PBMCs). The CD26 antigen is found on approximately 50% of CD4 and approximately 30% of CD8 cells. It is also found on some mature thymocytes, B cells, natural killer (NK) cells, monocytes, macrophages, epithelial cells, EBV transformed B-cell lines, and hairy cell leukemia. Absolute numbers of CD4+CD26+ and CD8+CD26+ cells are reported to be lower in HIV-positive individuals. The CD26-CD4+ cell appears to be a reservoir for HIV. CD26 bright CD4 lymphocytes are CD25+ and CD45RO+ memory T lymphocytes. The CD26 antigen can serve as a receptor for the coronavirus, MERS-CoV.
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.