The OX-61 monoclonal antibody specifically recognizes a type II transmembrane glycoprotein, CD26, which is a serine exoprotease identified as dipeptidyl/peptidase IV. Among various biological activities, rat CD26 binds fibronectin and collagen. Rat CD26 is involved in the costimulation of thymocyte proliferation in vitro, particularly the CD4-/CD8- subset, and is developmentally regulated on hematopoietic cells. Although mouse and human CD26 anchor ADA (adenosine deaminase) to cell membranes, rat CD26 does not function as an ADA-binding protein. Rat CD26 is expressed in lung endothelial cells, as well as in various epithelial cells. T cells express lower levels of CD26 than CD4-/CD8- thymocytes. The distribution of CD26 antigen in rat bone marrow cells is similar to that of human CD26. OX-61 monoclonal antibody stains CD4+, CD8+, and Ig+ lymphocytes, and the staining increases upon activation.
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).