Description: The BMA12 monoclonal antibody reacts with mouse CD100, also known as Sema4D. Sema4D/CD100 is a 150kDa transmembrane protein expressed constitutively on T cells and is involved in the activation of B cells through its interaction with CD72. Interaction of these two proteins diminishes the negative signaling normally effected by CD72. CD100 is already expressed strongly on resting T cells and somewhat weakly on B cells, but activation upregulates expression on both cell types. Antigen expression has been reported in Spleen, thymus and lymph nodes.