CD223 Rat anti-Mouse, PE, Clone: C9B7W, BD

Description

• The C9B7W antibody reacts with an epitope in the D2 domain of CD223 (LAG3), the 70kDa protein encoded by Lymphocyte-activation gene 3 (Lag3)
• A fusion protein consisting of the entire extracellular region of mouse LAG3 with mouse IgG1 was used as immunogen
• CD223 is a type-I membrane protein with four extracellular Ig-like domains; it is structurally homologous to CD4; and, like CD4, it binds MHC class II molecules
• However, unlike CD4, it is not expressed on resting T lymphocytes, in both the human and the mouse
• In the mouse, as previously described in the human, CD223 expression is upregulated on T lymphocytes (both CD4+ and CD8+) activated through the T-cell receptor (TCR) and on IL-2-activated NK (LAK) cells, and it is not detected on B cells, dendritic cells, or Phorbol 12-myristate 13-acetate (PMA)-stimulated splenocytes
• Studies on human peripheral T lymphocytes suggest that CD223 associates with the TCR to downregulate TCR signaling
• In contrast, in vivo and in vitro evaluations of vaccination protocols in mice suggest that CD223 promotes immune responses by activating antigen-presenting cells
• Furthermore, NK cells of Lag3-/- mice display defects in their capacity to kill certain tumor cells
• Mouse CD223 also has been demonstrated to contribute to the suppressor function of T regulatory cells and the C9B7W antibody has been shown to inhibit this function in vitro and in vivo
• Therefore, CD223 appears to play complex roles in the regulation of immune responses
• Although the C9B7W antibody is unable to block the binding of MHC class II-IgG2a fusion protein to CD223, it is able to block the CD223-mediated inhibition of IL-2 production by a T-cell hybridoma responding to antigen.