1D3-28Z.1-3–transduced T cells are superior to the 1D3 monoclonal antibody at treating lymphoma. Mice received 5 Gy of TBI, and later the same day they were injected subcutaneously with 38c13 lymphoma cells. Four days later when the mice had established lymphoma masses, they were separated into 4 treatment groups. One group received 1D3-28Z.1-3–transduced T cells. A second group received an injection of the 1D3 monoclonal antibody. A third group received an isotype-matched control antibody, and the fourth group was left untreated. Tumor sizes (A) and survival (B) of each group are shown. The P value of .004 refers to the comparison of the 1D3-28Z.1-3–transduced T-cell group and the 1D3 monoclonal antibody group. The tumor size curves of antibody-treated and untreated mice end when the first mouse of a group was killed. This is 1 of 2 representative experiments with 5 mice per group, except the No treatment group that contained 4 mice. (C) Mice that were successfully treated for lymphoma with 1D3-28Z.1-3–transduced T cells were resistant to lymphoma rechallenge. Three groups of mice received an intraperitoneal injection of 100 000 38c13 cells. Untreated mice had not received any prior treatment. Twenty weeks before rechallenge, mice in Treatment group 1 had lymphoma masses eradicated after treatment with 1D3-28Z.1-3-transduced T cells and IL-2 as detailed in Figure 6A. Sixteen weeks before rechallenge, mice in Treatment group 2 had lymphoma masses eradicated after treatment with 1D3-28Z.1-3 transduced T cells without IL-2 as described in panel A. The survival of the 3 groups is shown. The P value refers to the comparison of the untreated mice and the Treatment group 2.