The monoclonal antibody UC10-4B9 reacts with CD152, also known as cytotoxic T lymphocyte antigen-4 (CTLA-4), which is a 33 kDa member of the immunoglobin superfamily and is expressed on activated T cells at a low level. CTLA-4 and CD28 have similarities concerning B7 family counter-receptors. While CD28 delivers a costimulary signal in T cell activation, CD152 restricts the progression of T cells to an activated state by inhibiting interleukin 2 (IL-2) secretion and cellular proliferation. A large proportion of CTLA-4 is intracellular localized. For a complete detection it may be necessary to assess intracellular staining in addition to surface expression of CD152.
