Fig. 4.
CMA blocks CD44DL, ADCC, and natural cytotoxicity mediated by activated NK cells. (Upper panel) Lysis of TNP-MC1 cells by activated NK cells in the presence (open symbols) or absence (solid symbols) of 100 nmol/L CMA. Lysis was measured in the absence of antibody (squares), in the presence of anti-CD44 bsAb (CD44DL; circles), and in the presence of intact anti-DNP Ab (ADCC; triangles). (Middle panel) Blockage of natural cytotoxicity against the Fas-negative, NK-sensitive target, K562 with 10, 100, and 1,000 nmol/L CMA. (Lower panel) Partial inhibition of lysis of Jurkat cells, which are Fas-positive and NK-sensitive, by 10, 100, and 1,000 nmol/L CMA. All experiments were repeated four times, with similar results, except for the inhibition of Jurkat lysis, which was repeated twice. Pretreatment of effector cells with 100 nmol/L CMA for 1 hour at 37°C, followed by washing, gave similar results.