ABSTRACT
Natural killer (NK) cells are implicated in the surveillance of hematological malignancies. They participate in the immune response against residual acute myeloid leukemia (AML) after hematopoietic stem cell transplantation with partial HLA class I disparity. However, the role of NK cells in autologous leukemia-specific immunity remains poorly understood. We studied the function of NK cells in AML patients at diagnosis. Following isolation, CD56+CD3- cells exhibited a high proliferative potential in vitro in response to interleukin (IL)-2. The polyclonal population of activated AML-NK cells expressed normal levels of the activating receptor NKG2D and the major natural cytotoxicity receptor NKp46. AML-NK cells were highly effective with respect to interferon-gamma production, cytotoxicity against HLA class I-deficient K562 erythroleukemia cells in vitro and retardation of tumor growth in vivo in K562-bearing NOD/SCID mice. Importantly, when AML blasts were injected into NOD/SCID mice, a single dose of adoptively transferred autologous AML-NK cells significantly reduced the AML load by 8-77%. Recognition of AML blasts may be related to the observed upregulation of ligands for NKG2D and natural cytotoxicity receptors in vivo. We conclude that AML patient-derived NK cells are fully functional, in support of exploring the benefit of AML immunotherapy with IL-2-stimulated autologous NK cells.
Subject(s)
Blast Crisis/therapy , Cytotoxicity, Immunologic , Killer Cells, Natural/physiology , Leukemia, Myeloid/immunology , Leukemia, Myeloid/pathology , Acute Disease , Animals , Humans , Immunotherapy, Adoptive , K562 Cells , Killer Cells, Natural/transplantation , Leukemia, Myeloid/therapy , Lymphocyte Activation , Mice , Mice, Inbred NOD , Mice, SCID , Transplantation, Heterologous , Tumor Burden , Tumor Cells, Cultured , Up-RegulationABSTRACT
Panels of human antigen-specific T cell clones (TCC) have been established by limiting dilution using Herpesvirus saimiri (HVS) subtype C transformed T cells as antigen presenting cells (APC). They showed antigen-specific proliferation when peripheral blood mononuclear cells (PBMC), HVS-transformed T cells and Epstein Barr Virus transformed lymphoblastoid B cell lines (EBV-LCL) were used as APC. All T cell clones were CD4+ and HLA class II restricted. For a detailed analysis, two panels of T cell clones specific for an epitope located in the N-terminus of the Merozoite Surface Protein 1 (MSP-1) of Plasmodium falciparum were established from the same founder T cell line using either PBMC or HVS-transformed T cells as APC. TCR analysis of the two panels of TCC demonstrated that the same founder cells could be propagated in both culture systems. Furthermore, no difference in the cytokine expression pattern or antigen processing and co-stimulatory requirements was observed between TCC established on PBMC or HVS-transformed T cells. Based on the finding that HVS-transformed T cells can replace PBMC as APC for isolation and propagation of antigen-specific TCC, a protocol was developed and successfully executed, which allows to establish and maintain vaccine-specific T cell clones from 20 ml of blood. This method might be particularly significant in clinical trials of immune intervention strategies.
