The GAP.A3 monoclonal antibody specifically recognizes the polymorphic HLA class I histocompatibility antigen, A-3 alpha chain (HLA-A3). This ~44 kDa human major histocompatibility complex (MHC) class I molecule noncovalently associates with the ~12 kDa monomorphic β2 microglobulin. Two major subtypes are encoded by HLA-A3, HLA-A3.1 and HLA-A3.2. HLA-A3 gene expression is more commonly detected in individuals from Europe and southern India. HLA-A3 is expressed on nearly all nucleated cells of HLA-A3-positive individuals. HLA-A3 functions in the presentation of antigens to CD8-positive T cells which may lead to the generation of HLA-A3-restricted cytotoxic T cells and memory T cells. When complexed with certain antigens, HLA-A3 can also bind to killer cell immunoglobulin-like receptors (KIR), such as KIR3DL2, and might regulate NK cell function.
Note: Since HLA-A3 expression varies between human populations, clone GAP.A3 staining can be donor-dependent. Based on in-house testing and current literature, individuals of European or Southern Indian descent more frequently express HLA-A3 than those of Asian descent. Data may differ between donors due to geographical variations of HLA-A3 expression.
The antibody was conjugated to BD Horizon™ BUV661 which is part of the BD Horizon Brilliant™ Ultraviolet family of dyes. This dye is a tandem fluorochrome of BD Horizon BUV395 with an Ex Max of 348-nm and an acceptor dye with an Em Max at 661-nm. BD Horizon Brilliant BUV661 can be excited by the ultraviolet laser (355 nm) and detected with a 670/25 filter and a 630 nm LP. Due to cross laser excitation of this dye, there may be significant spillover into channels detecting APC-like emissions (eg, 670/25-nm filter).
Due to spectral differences between labeled cells and beads, using BD™ CompBeads can result in incorrect spillover values when used with BD Horizon BUV661 reagents. Therefore, the use of BD CompBeads or BD CompBeads Plus to determine spillover values for these reagents is not recommended. Different BUV661 reagents (eg, CD4 vs. CD45) can have slightly different fluorescence spillover therefore, it may also be necessary to use clone-specific compensation controls when using these reagents.