The R3-242 monoclonal antibody specifically binds to aminopeptidase N (APN), which has been reported to be the mouse CD13 homologue. APN is expressed in a variety of mammalian tissues, including intestinal and renal epithelial brush border, endothelium, liver, lung, and brain. In lymphoid tissues, R3-242 mAb is reported to detect APN on monocytes, macrophages, mast cells, dendritic cells, and B lymphocytes, but not on T cells, and thymocytes. However, the reported reactivity with B cells may be non-specific, via binding to the Fcγ receptors (CD16/CD32). This observation is in agreement with reports using different antibodies to mouse APN. APN may play a role in antigen presentation in the immune system. R3-242 mAb does not inhibit the enzymatic activity of APN.
The antibody was conjugated to BD Horizon™ BV650 which is part of the BD Horizon Brilliant™ Violet family of dyes. This dye is a tandem fluorochrome of BD Horizon BV421 with an Ex Max of 405-nm and an acceptor dye with an Em Max at 650-nm. BD Horizon BV650 can be excited by the violet laser and detected in a filter used to detect APC-like dyes (eg, 660/20-nm filter). Due to the excitation and emission characteristics of the acceptor dye, there will be spillover into the APC and Alexa Fluor® 700 detectors. However, the spillover can be corrected through compensation as with any other dye combination.