The H194-112 monoclonal antibody specifically binds to CD26, which is also known as, Thymocyte-activating molecule (THAM), or dipeptidyl peptidase IV (DPP IV, Dpp4). CD26 is a ~220- kDa dimer formed of identical type-II transmembrane core polypeptides which undergo variable post-translational modifications. It is a multi-functional molecule with both ectopeptidase and signal-transducing activities. Studies with specific DPP IV inhibitors suggest that the enzymatic activity is involved in the mediation of T-cell activation events. The expression of CD26 is developmentally regulated in the thymus. Resting lymphoid cells of the bone marrow and peripheral B and T lymphocytes express low levels of CD26; bone-marrow and peritoneal myeloid cells do not. CD26 is also found on epithelial cells in the kidney, liver, small intestine, and lung. Cross-linked H194-112 mAb induces proliferation of immature and mature thymocytes in the presence of either IL-1 plus IL-2 or PMA; addition of IL-2 or IL-4 to PMA further enhances the activation.
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.