Some anti–human CTLA-4 mAbs prolong survival and delay onset of lymphoproliferative disorder in hu-PBL-SCID mice. CB.17 SCID mice were engrafted with 50 × 106 human PBLs and were treated with 100 μg TMβ1 mAb the same day, followed by 100 μL ascites containing anti–human CTLA-4 mAbs or 100 μg mouse IgG and 3 μg human GM-CSF on days 1, 5, and 9, and 13 after engraftment. Mice were monitored for signs of illness and were killed when moribund. One L3D10-treated mouse with early death on day 15 and 1 KM10G11-treated mouse with early death on day 13 were excluded from the survival analysis based on our experience that no lymphoma-related death is possible at this point. Survival times of the antibody-treated groups were compared with those of the control IgG-treated group using the log rank test. Probability values were as follows: mouse IgG versus L3D10, P = .0195; mouse IgG versus L1B11, P = .481; mouse IgG versus K4G4, P = .323; mouse IgG versus KM10G11, P = .045; mouse IgG versus YL2, P = .324.
