The OF-5A12 monoclonal antibody specifically recognizes the human variable alpha 7.2 region of the T cell receptor for antigen (TCR Vα7.2) that is joined with the Jα33 segment to form an invariant TCR which is characteristically expressed by mucosal-associated invariant T cells (MAIT cells). MAIT cell recognition of antigen is restricted by MHC-related molecule 1 (MR1), a nonpolymorphic Class Ib Major Histocompatibility Complex (MHC) molecule, that associates with β2-microglobulin. MAIT cells are found in human peripheral blood, mesenteric lymph nodes, liver, and mucosa associated with the lungs and intestines. MAIT cells play a role in detecting and fighting off microbial infections. The specificity of OF-5A12 for the TCR Vα7.2 was confirmed by its ability to block the binding of another human TCR Vα7.2-specific antibody, 3C10, to MAIT cells.
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.