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 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).