title: Human umbilical cord blood NK T cells kill tumors by multiple cytotoxic mechanisms.
abstract: Natural killer (NK) T cells are restricted by CD1d and play an important role in the rejection of malignant tumors, but how kill these tumors is unclear. To investigate this, we cultured Valpha24+CD4+ NK T cells in human umbilical cord blood, which was enriched by immunomagnetic beads. In short-term (4 h) cytotoxicity assays, the NK T cells could kill only those targets expressing CD1d. In longer cytotoxicity assays (20 h), however, the NK T cells were able to kill all the tumors, regardless of CD1d expression. When each of the perforin, Fas-FasL, and TNF-alpha cytotoxic mechanisms were blocked, it was apparent that perforin killing dominated in both the short- and long-term assays. In the short-term assay, perforin killing required that the targets expressed CD1d, but killing was more efficient if Fas was present because then the Fas-FasL mechanism was also used. Thus, cells that lacked Fas and CD1d and were not killed in the 4-h assay, were instead lysed in 20-h assay through a combination of perforin and TNF-alpha killing. NK T cells can kill tumor targets by perforin, Fas-FasL, and TNF-alpha mechanisms. TNF-alpha killing requires longer contact between effectors and targets, suggesting that TNF-alpha acts by enhancing perforin killing.
authors.affiliation: Department of Hematology and Rheumatology, Kanagawa, Japan.
authors.forename: Balgansuren
authors.initials: B
authors.lastname: Gansuvd
authors.forename: Masao
authors.initials: M
authors.lastname: Hagihara
authors.forename: Ying
authors.initials: Y
authors.lastname: Yu
authors.forename: Hiroyasu
authors.initials: H
authors.lastname: Inoue
authors.forename: Yoko
authors.initials: Y
authors.lastname: Ueda
authors.forename: Takahide
authors.initials: T
authors.lastname: Tsuchiya
authors.forename: Aya
authors.initials: A
authors.lastname: Masui
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Ando
authors.forename: Yoshihiko
authors.initials: Y
authors.lastname: Nakamura
authors.forename: Namid
authors.initials: N
authors.lastname: Munkhtuvshin
authors.forename: Shunichi
authors.initials: S
authors.lastname: Kato
authors.forename: Judith M
authors.initials: JM
authors.lastname: Thomas
authors.forename: Tomomitsu
authors.initials: T
authors.lastname: Hotta
mesh_terms: D018949:Antigens, CD1 / Q000276:immunology* / Q000378:metabolism; D055610:Antigens, CD1d; D015496:CD4-Positive T-Lymphocytes / Q000378:metabolism; D002478:Cells, Cultured; D016207:Cytokines / Q000032:analysis / Q000276:immunology; D003602:Cytotoxicity, Immunologic; D003713:Dendritic Cells / Q000276:immunology / Q000378:metabolism; D053222:Fas Ligand Protein; D005260:Female; D005312:Fetal Blood / Q000276:immunology*; D006801:Humans; D007371:Interferon-gamma / Q000032:analysis; D007694:Killer Cells, Natural / Q000276:immunology* / Q000378:metabolism; D007959:Lymphocyte Culture Test, Mixed; D008562:Membrane Glycoproteins / Q000276:immunology* / Q000378:metabolism; D009369:Neoplasms / Q000276:immunology* / Q000378:metabolism; D054353:Perforin; D052899:Pore Forming Cytotoxic Proteins; D014409:Tumor Necrosis Factor-alpha / Q000276:immunology
chemical_list: D018949:Antigens, CD1; D055610:Antigens, CD1d; C526877:CD1D protein, human; D016207:Cytokines; C505661:FASLG protein, human; D053222:Fas Ligand Protein; D008562:Membrane Glycoproteins; D052899:Pore Forming Cytotoxic Proteins; D014409:Tumor Necrosis Factor-alpha; D054353:Perforin; D007371:Interferon-gamma