Description: The BTLA monoclonal antibody reacts with human B and T lymphocyte attenuator (BTLA). BTLA is expressed by peripheral lymphocytes, splenic macrophages, developing B cells in the bone marrow and developing T cells in the thymus and mature, but not immature bone marrow-derived dendritic cells. BTLA is implicated as a negative regulator of the activation and/or function of various hemopoietic cell types. It is reported that BTLA binds to B7-H4, but further studies are needed to confirm this interaction.