Figure 4

Hyperexpanded CD4⁺ T cells mediate regression of intracranial or subcutaneous tumors. (A) CD62L^low TDLN cells were depleted of CD8⁺ cells prior to anti-CD3 activation and were maintained in medium with IL-2 (4 U/ml) plus IL-7 (10 ng/ml) or alternatively with IL-7 (10 ng/ml) plus IL-23 (2 ng/ml) and were restimulated for 14 hrs with anti-CD3 mAb at the indicated time points. The total proliferation with indicated losses due to AICD or re-purification of CD4⁺ cells is indicated. (B) Mice bearing 3-day s.c.tumors were treated with 5 Gy TBI followed by adoptive transfer of 3 × 10⁷ CD4⁺ T cells culture activated for 43 days and tumor size was measured. On day 37, one mouse from IL-2 + IL-7 group was euthanized due to progressive tumor growth, however complete regression was observed in the remaining 4 mice (P = 0.015 versus control). Complete regression was observed in all five recipients of IL-7 + IL-23 cultured CD4⁺ T cells (P = 0.005 versus control). (C) Mice bearing 3-day intracranial tumors were treated with 5Gy TBI followed by adoptive transfer of 3 × 10⁷ CD4⁺ T cells culture activated for 43 days. Mice were followed for survival (P < 0.01 for both treatment groups versus control). (D) Mice bearing 3-day subcutaneous tumors were treated with 5 Gy TBI followed by adoptive transfer of 4 × 10⁷ CD8⁺ T cells hyperexpanded to greater than 10⁸-fold for 50 days, or 1.5 × 10⁷ CD4⁺ T cells hyperexpanded to greater than 10⁸-fold for 85 days. On day 28, 4 mice from CD8 treatment group (* P = 0.39 versus control) and 2 mice from CD4 treatment group (# P = 0.019 versus control) were euthanized due to progressive tumor growth but complete tumor regression was observed in the remaining mice.