The 232-5 monoclonal antibody specifically recognizes Butyrophilin 3 (BTN3), which is also known as CD277. BTN3 is comprised of three structurally related members, BTN3A1, BTN3A2, and BTN3A3. BTN3 molecules are transmembrane type 1 glycoproteins that belong to the Ig superfamily. The 232-5 antibody recognizes the variable region of the extracellular domains of BTN3 molecules. BTN3 molecules are differentially expressed by T, NKT, B, and NK cells, monocytes, macrophages, dendritic cells, as well as some stem cells and tumor cells. BTN3 expression is decreased upon lymphocyte activation. The extracellular domain of CD277 is structurally related to the B7 family of proteins that regulate T cell activation. A soluble form of the 232-5 antibody can serve as an agonist in BTN3-mediated regulation of anti-CD3 ± anti-CD28 antibody activated CD4+ or CD8+ T cells.
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.