T cells (19mz/IL-12⁺) induce B-cell aplasias and tumor eradication in the absence of prior cyclophosphamide conditioning. (A) Schematic of CAR/IL-12 retroviral constructs. IRES indicates internal ribosome entry site. (B) 19mz and 19mz/IL-12 expression after retroviral gene transfer as assessed by flow cytometry demonstrated similar gene transfer. (C) Supernatant from 19mz/IL-12⁺ but not 19mz⁺ T cells demonstrates enhanced levels of IL-12p70. (D) B-cell aplasias in EL4(hCD19) tumor-bearing C57BL6(mCD19^−/−hCD19^+/−) mice treated with 19mz/IL-12, but not Pmz/IL-12 or 19mz⁺ T cells, as assessed by flow cytometric analysis of peripheral blood samples at 2 weeks postmodified T-cell infusion. (E) 19mz/IL-12⁺ T cells eradicated disease and enhanced the survival of EL4(hCD19) tumor-bearing mice. In contrast, Pmz/IL-12 T cells significantly enhanced the survival of EL4(hCD19) tumor-bearing mice compared with 19mz⁺ T cell treated mice but similarly failed to eradicate disease. (F) Tregs in the BM of 19mz/IL-12⁺ and 19mz⁺ T cell treated mice as assessed by flow cytometry. All results are representative of at least 2 independent experiments.