J. Cancer Mol. 2: 221-226, 2006

[Research Paper]

Induction of Significant Cytotoxic Activity for Autologous Leukemia Cells: Inverse Correlation between Cytotoxicity and FOXP3 mRNA Expression

Yasuki Hijikata, Yasuhiro Maeda, Terufumi Yamaguchi, Yasuyoshi Morita, Miyako Tanaka, Chikara Hirase, Shunsuke Takai, Yoichi Tatsumi, and Akihisa Kanamaru 

Department of Hematology, Kinki University School of Medicine, Osaka, Japan

Abstract:

AIM: The goal of this study is to investigate whether immunotherapy using autologous cytotoxic T-lymphocytes has become available to eradicate minimal residual disease in acute leukemia.

METHODS: In this study, to generate cytotoxic T-lymphocytes (CTL), a mixed culture was carried out.  Two stimulator cells, the original leukemia cells (LCs) and the new lymphoblastoid B-cell line (LCLs) established by transformation with Epstein-Barr virus, were prepared.  Cytotoxic activity was examined using (1) peripheral blood mononuclear cells (PBMCs) only, (2) PBMCs plus interleukin-2, or (3) PBMCs plus LCs or LCLs plus interleukin-2.  After mixed culture for 5 days, cytotoxic activity was examined by flow cytometry with PKH-26 staining.

RESULTS: Interestingly, cytotoxicity to not only autologous LCs but also own LCLs was observed in most cases.  There is a close relationship between the cytotoxicity to LCs and that to LCLs.  This cross-killing phenomenon supports that cell therapy as an immunotherapy should be useful for improving the prognosis, and if stocked LCs is not available, effective CTL activity can be induced by a mixed culture with established own LCLs.  An inverse correlation was also observed between cytotoxicity and FOXP3 mRNA expression.

CONCLUSION: The generation of cytotoxic activity against autologous LCs can be induced by cultivating PBMCs with either LCs or LCLs.

Received 10/3/06; Revised 11/19/06; Accepted 11/20/06.

¹Correspondence: Dr. Yasuhiro Maeda, Department of Hematology, Kinki University School of Medicine, 377-2, Ohno-Higashi, Osaka-Sayama, Osaka 589-8511, Japan. Phone: 81-72-366 0221 ext 3128. Fax: 81-72-368 3732. E-mail: ymaeda@med.kindai.ac.jp

²Abbreviations: AL, acute leukemia; allo-HSCT, allogeneic hematopoietic stem cell transplantation; GvL, graft-versus-leukemia; TAA, tumor-associated antigen; HLA, human leukocyte antigen; LC, leukemia cell; CR, complete remission; LCL, lymphoblastoid B-cell line; EBV, Epstein-Barr virus; CTL, cytotoxic T-lymphocyte; APC, antigen-presenting cell; PBMC, peripheral blood mononuclear cell; IL, interleukin; Treg, regulatory T cells; FITC, fluorescein isothiocyanate; PHA, phytohaemagglutinin; DLI, donor lymphocyte infusion.