The 6A8.6F10.1A6 monoclonal antibody reacts with the Qa-1[b] alloantigen, which is a nonclassical MHC class I (Class Ib) molecule encoded by the T23 gene of the H-2 complex (H2-T23). Qa-1 associates with β2-microglobulin and is expressed at low levels on most leukocytes and many other cell types. Its level of cell-surface expression is upregulated by IFNγ or specific peptides. Qa-1 is an oligomorphic molecule which presents a limited pool of peptides to T lymphocytes bearing αβ and γδTCR and binds to a large subpopulation of NK cells. In fact, Qa-1[b] is the ligand for CD94/NKG2A, CD94/NKG2C, and CD94/NKG2E receptors, which are expressed on NK cells. Furthermore, it has been reported that Qa-1 expressed on activated B lymphocytes is involved in immunoregulation by inducing T-cell-mediated suppression of antibody responses. The 6A8.6F10.1A6 mAb can detect Qa-1[b] on activated splenocytes from C57BL/6 and BALB/c mice (both Qa-1[b]), but not from A/j mice (Qa-1[a]), and it can block target cell recognition by CTLs specific for Qa-1-presented antigen.
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.