The TU39 monoclonal antibody specifically recognizes human major histocompatibility (MHC) Class II HLA-DR, DP and most DQ antigens. These antigens are encoded by genes within the Human Leukocyte Antigen (HLA) Complex located on chromosome 6. MHC Class II antigens are transmembrane heterodimeric glycoproteins composed of α chain (36 kDa) and β chain (27 kDa) subunits. They are expressed primarily on antigen presenting cells which include dendritic cells, monocytes, macrophages, thymic epithelial cells, and B cells. They are also expressed on activated T cells. This molecule plays a major role in mediating cellular interactions during antigen presentation to CD4+ T lineage cells. The TU39 antibody is reportedly useful for immunophenotyping as well as functional studies including the inhibition of mixed lymphocyte reactions and antibody-mediated complement fixation on target 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.