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™ BUV563 which is part of the BD Horizon Brilliant™ Ultraviolet family of dyes. This dye is a tandem fluorochrome of BD Horizon BUV395 which has an Ex Max of 348 nm and an acceptor dye. The tandem has an Em Max at 563 nm. BD Horizon BUV563 can be excited by the 355 nm ultraviolet laser. On instruments with a 561 nm Yellow-Green laser, the recommended bandpass filter is 585/15 nm with a 535 nm long pass to minimize laser light leakage. When BD Horizon BUV563 is used with an instrument that does not have a 561 nm laser, a 560/40 nm filter with a 535 nm long pass may be more optimal. Due to the excitation and emission characteristics of the acceptor dye, there may be spillover into the PE and PE-CF594 detectors. However, the spillover can be corrected through compensation as with any other dye combination.