The monoclonal antibody BB7.2 specifically binds to the α subunit of the human leukocyte antigen-A2 (HLA-A2), a class I molecule of the major histocompatibility complex (MHC). The MHC gene locus encodes a group of highly polymorphic, cell-surface proteins that play a broad role in the immune response to protein antigens. MHC molecules bind and present small antigenic protein fragments to antigen-specific receptors expressed by T cells (TCR). Human (human leukocyte antigen/HLA) MHC molecules are comprised of two major classes, MHC class I and class II. Functionally, class I MHC molecules bind peptides derived from intracellular antigens (eg, viral and some bacterial antigens) which are specifically recognized by CD8+ T cells. Class II MHC molecules bind antigens derived from pathogens multiplying in intracellular vesicles and ingested extracellular bacteria, both of which are recognized by CD4+ T cells. TCR recognize processed peptides bound to the MHC as well as regions of the MHC molecule itself. CD4 and CD8 accessory molecules strengthen the formation of the TCR-MHC complex through their interaction with non-polymorphic regions of the MHC molecule.
The antibody was conjugated to BD Horizon BUV615 which is part of the BD Horizon Brilliant™ Ultraviolet family of dyes. This dye is a tandem fluorochrome with an Ex Max near 350 nm and an Em Max near 615 nm. BD Horizon Brilliant BUV615 can be excited by the ultraviolet laser (355 nm) and detected with a 610/20 filter and a 595 nm LP. Due to the excitation of the acceptor dye by the blue/yellow-green laser line, there may be significant spillover into channels detecting PE-CF594 like emissions (eg, 610/20-nm filter).