Description: The A7R34 monoclonal antibody reacts with mouse CD127, the high affinity alpha subunit of the mouse IL-7 receptor. IL-7 receptor alpha chain is expressed by immature B cells in the bone marrow, double-negative (CD4-CD8-), single-positive (CD4+ and CD8+), but not double-positive (CD4+CD8+) thymocytes. In the periphery, mature T cells express CD127 at low level. A7R34 inhibits binding of IL-7 to its receptor and has been used in in vivo and in vitro studies to elucidate the role of IL-7 in T and B cell development and activation. Binding of A7R34 blocks the binding of SB/199, another antibody which recognizes mouse CD127.