Figure 6.

CD40 ligand crosslinking induces redirected cytotoxicity. P815 cells were incubated with 200 ng of anti-CD40L mAb TRAP-1 (closed circles), the isotypic control OX27 (open triangles), or medium (open circles) and then used as target in an in vitro cytotoxicity assay. The results refer to one of five independent experiments. A and B show data obtained by using as effectors NK3.3 cells cultured in the presence of rIL-2 or starved from IL-2 for 24 h, respectively. C shows data obtained by using NK3.3 effectors pre-incubated for 4 h at 37°C in the presence of plastic immobilized TRAP-1 mAb, or the control OX27 mAb. The treatment was performed in a 96-well microtiter plate precoated with 50 μl of the antibody solution, at the concentration of 10 μg/ml. NK effectors were collected and used in a classical chromium release assay. Closed and open circles indicate preincubation of effectors in the presence of plastic immobilized TRAP-1 or OX27 control mAb, respectively. The results refer to one of four independent experiments.