The J168-540 monoclonal antibody specifically binds to human CD272, also known as BTLA (B and T lymphocyte attenuator), an inhibitory receptor expressed in bone marrow and thymus on developing B and T cells. In the periphery, BTLA is expressed by B cells, T cells, bone marrow-derived dendritic cells, and macrophages. After T cell activation, BTLA appears to be expressed at higher levels on Th1 cell populations than in Th2 cell populations. Upon binding the herpesvirus entry mediator (HVEM/LIGHT-R/CD270), CD272 undergoes tyrosine phosphorylation and inhibits T cell proliferation in a BTLA-dependent manner. CD272 has structural similarities to two other lymphocyte inhibitory receptors, CTLA-4 and PD-1 and is a member of the CD28-like family of coreceptors. Based on these observations, CD272 is considered to be a negative regulator of lymphocyte activation and/or function.
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.