The result of repertoire sequences demonstrated that FACS-purified GFP+WT1 tetramer+CD8+T cells displayed skewing of both V and V repertoires and that the majority of V and V chains of the T cells were the transduced V and V chains (Figure 6)

The result of repertoire sequences demonstrated that FACS-purified GFP+WT1 tetramer+CD8+T cells displayed skewing of both V and V repertoires and that the majority of V and V chains of the T cells were the transduced V and V chains (Figure 6). Next, we transplanted the WT1-specific T-cell receptor (WT1-TCR) genetransduced human HSCs into HLA class I Tg NSG newborn mice. WT1 tetramer-positive CD8+T cells differentiated from WT1-TCR-transduced HSCs in the recipients BM, spleen, and thymus. Upon stimulation with WT1 peptide in vitro, these CTLs produced interferon- and showed lytic activity against leukemia cells in an antigen-specific, HLA-restricted manner. HLA class I Tg NSG xenografts may serve as a preclinical model to develop effective immunotherapy against human malignancies. == Introduction == The immune system prevents infectious disease initiation and progression and functions in multiple homeostatic processes. However , dysfunctional immunity is observed in patients with malignancies, contributing to neoplastic progression. Therefore , reconstitution of immunity by allogeneic stem cell transplant or activation of specific and nonspecific immunity-targeting diseases improves clinical outcomes in patients with solid cancers and in those with hematologic malignancies. 1, 2Such treatment can be carried out by vaccination and by adoptive immunotherapy. Vaccinations aim to elicit antigen-specific effector cellmediated immune responses in vivo. 3Among several candidates, peptide vaccines and dendritic cell (DC) vaccines were 2 widely selected protocols. In the last 2 decades, however , administration of these vaccines has not significantly improved the prognosis of patients with solid cancers including melanoma and other types of solid tumors. 4, 5Although several recent trials reported encouraging clinical outcomes using glycoprotein 100 peptides in combination with interleukin (IL)-2 for the treatment of melanoma, 6or patient-derived antigen-presenting cells (APCs; sipuleucel-T) for the treatment of prostate cancer, 7cancer vaccination appears to require modifications based on increased understanding of in vivo biology of human APCs and T cells. In contrast, immunotherapy based on adoptive transfer of ex vivo expanded tumor-reactive T cells has achieved promising results. In metastatic melanoma, adoptive transfer of tumor-infiltrating lymphocytes in combination with chemotherapy or irradiation has improved cure rates up to 20% to 40%. 8Because the antitumor effect of tumor-infiltrating lymphocytes has not been confirmed in malignancies other than melanoma, genetically engineered T cells that express tumor antigenspecific T-cell receptor (TCR) genes or chimeric antigen receptors have been developed. 9Recent clinical trials showed improved clinical outcomes in patients treated with genetically engineered T cells, 10-13whereas adverse effects were observed immediately after the transfusion of T cells expressing chimeric antigen receptors. 14, 15 In several clinical trials of vaccination therapies for hematologic malignancies, promising responses were observed using various antigens, including proteinase 316and Wilms tumor 1 (WT1)16, 17for acute myeloid leukemia (AML), breakpoint cluster region/Abelson murine leukemia for chronic myelogenous leukemia, 18and patient-specific idiotypes derived from malignant B-cell clones for follicular lymphoma. 19In particular, for patients with poor prognostic factors, development of immunotherapy targeting minimal residual disease or leukemia Cefixime stem cells (LSCs) should play an essential role in achieving long-term patient survival. We recently reported that WT1, a transcription factor expressed in variety of malignant tissues, is highly expressed by Cefixime CD34+CD38AML cells. 20WT1 is considered one of the best antigens to be used for immunotherapy against malignancies, based on multiple criteria such as therapeutic function, immunogenicity, and specificity. 21Using WT1 peptide or full-length messenger (m)RNA for WT1, clinical trials against hematologic malignancies detected increased frequencies of WT1-specific CD8+T cells in patient blood after the treatment. 16, 17, 22, 23Nevertheless, to accomplish significant improvement in clinical outcomes of AML patients, we need to better understand the biology of the human immune system leading to efficient activation of human acquired immunity against tumor antigens. In the present study, we aimed to develop an in vivo system for induction of antigen-specific, HLA-restricted human CD8+T cells after vaccination. HLA class Iexpressing NOD/SCID/IL2rgKO (NSG) mice supported the development of human T cells and APCs after engraftment with human cord blood (CB) HSCs. We detected high frequencies of WT1-specific CD8+T cells Cefixime in the bone marrow (BM) and spleen of HLA class Iexpressing NSG mice after vaccination. Moreover, we confirmed the development of WT1-specific CD8+T cells in vivo after engraftment of human HSCs transduced with WT1-specific TCR (WT1-TCR) V and V genes. The antigen-specific human CD8+T cells expanded in response to WT1 antigen and were functional both in cytokine production and cytotoxicity. Development of immunotherapy protocols in HLA class Iexpressing NSG mice may facilitate the development and optimization of antigen-specific immunotherapy against malignancies. == Materials and methods == Detailed experimental methods are described in supplemental Methods, available on theBloodWeb site. == Flow cytometry == For phenotypical analysis, cells labeled with monoclonal antibodies (mAbs) (supplemental Table 1) were analyzed using Plau FACSAria and Cefixime FACSCanto II instruments (BD Biosciences). == Immunization of humanized mice.