(c) Luciferase activity in Jurkat cells transfected as in a, then left uninoculated (−) or inoculated with 10 × 108 E. coli F18 (+), followed by the addition of monoclonal antibody (mAb; amount, under graph) 9D1 to SLAM (α-SLAM) or rat immunoglobulin G2b isotype-matched control antibody (Rat IgG2b). 