The YTH 76.3rMAb is a recombinant monoclonal antibody that specifically recognizes a monomorphic epitope on the extracellular region of the Human Leukocyte Antigen-B (HLA-B) heavy chain. This major histocompatibility complex (MHC) class I antigen is comprised of a polymorphic HLA-B heavy chain, a ~45 kDa type I transmembrane glycoprotein encoded by HLA-B, that is noncovalently associated with the invariant ~12 kDa Beta-2 (β2)-microglobulin light chain encoded by B2M. Hundreds of HLA-B alleles have been reported. HLA-B is expressed on most nucleated cells and leucocytes including specialized antigen presenting cells such as thymic epithelial cells and dendritic cells. HLA-B plays a major role in the MHC-restricted presentation of small peptides, including those derived from self or foreign antigens, that can be bound by TCR expressed on CD8+ thymocytes or T cells leading to either immune tolerance, the maturation of naïve CD8+ T cells, or the activation and differentiation of CD8+ cytotoxic effector T cells or memory CD8+ T cells. HLA-B also functions as a ligand for regulatory CD8 coreceptor molecules and some CD158 molecules that serve as regulatory MHC class I antigen receptors expressed by CD8+ T cells and NK cells. The YTH 76.3rMAb is derived from the hybridoma clone YTH 76.3, with Rat IgG2a, κ isotype. YTH 76.3rMAb has variable region sequences from the original YTH 76.3 clone appended to Rat IgG1 and kappa constant region sequences.
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.