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™ BV650 which is part of the BD Horizon Brilliant™ Violet family of dyes. This dye is a tandem fluorochrome of BD Horizon BV421 with an Ex Max of 405-nm and an acceptor dye with an Em Max at 650-nm. BD Horizon BV650 can be excited by the violet laser and detected in a filter used to detect APC-like dyes (eg, 660/20-nm filter). Due to the excitation and emission characteristics of the acceptor dye, there will be spillover into the APC and Alexa Fluor™ 700 detectors. However, the spillover can be corrected through compensation as with any other dye combination.