Killing activity of human umbilical cord blood-derived TCRValpha24(+) NKT cells against normal and malignant hematological cells in vitro: a comparative study with NK cells or OKT3 activated T lymphocytes or with adult peripheral blood NKT cells.
OBJECTIVE
We aimed to determine the effects of human umbilical cord blood (UCB)-derived natural killer T (NKT) cells as immunological effectors against hematological malignancies, as well as auto- or allo-dendritic cells (DCs) or EB transformed cell lines (EBCLs).


METHODS
TCRValpha24(+) Vbeta11(+) UCB- or PB-NKT cells were isolated by sorting and activated by alpha-galactosylceramide-pulsed autologous DCs. UCB-NK cells were induced from CD34(+) cells by stem cell factor plus IL-15. UCB-T cells were primarily activated by anti-CD3 monoclonal antibody. All those effectors were cultured with IL-2 (100 U/ml), and their cytotoxic activities were evaluated by (51)Cr-release assay. UCB-NKT cells were cultured with IL-12, IL-18 or higher dose of IL-2 (1000 U/ml), and again tested for the cytotoxicity against selected targets.


RESULTS
UCB-NKT cells exhibited a pattern of killing activity against various hematological malignancies similar to that of UCB-NK cells, but could not kill K562, which was a vulnerable target for NK cells. The level of activity was quite similar to that of PB-NKT cells. In contrast, OKT-3-activated UCB-T lymphocytes showed a stronger and wider spectrum of killing compared with UCB-NK or NKT cells. IL-12, IL-18 or a higher dose of IL-2 upregulated the activity; however several targets, including fresh leukemic cells, still remained resistant. NKT cells killed auto- or allo-DCs at a level similar to that of T cells, but could not kill allo-EBCLs, which were efficiently killed by T cells. While NK cells showed only marginal or no killing against DC or EBCLs.


CONCLUSIONS
The anti-cancer activity of human NKT cells depends on the concentrations or the combination of Th1-cytokines. Basically, those cells might not be contributing to the immune surveillance of hematological malignancies, as shown by a relatively low cytotoxicity against malignant cells, together with the quite strong killing against auto-DCs.
Hagihara
Masao
M
Department of Hematology and Rheumatology, Tokai University School of Medicine, Bohseidai, Isehara, Kanagawa, Japan 259-1193. masaoha@is.icc.u-tokai.ac.jp
Gansuvd
Balgansuren
B
Ueda
Yoko
Y
Tsuchiya
Takahide
T
Masui
Aya
A
Tazume
Kei
K
Inoue
Hiroyasu
H
Kato
Shunichi
S
Hotta
Tomomitsu
T
D018949:Antigens, CD1 / Q000032:analysis / Q000276:immunology; D055610:Antigens, CD1d; D000951:Antigens, Neoplasm / Q000032:analysis / Q000276:immunology; D015551:Autoimmunity; D001773:Blood Cells; D002461:Cell Line, Transformed; D002469:Cell Separation; D003602:Cytotoxicity, Immunologic / Q000187:drug effects; D003713:Dendritic Cells / Q000276:immunology; D004305:Dose-Response Relationship, Drug; D005312:Fetal Blood / Q000166:cytology* / Q000276:immunology; D005434:Flow Cytometry; D005699:Galactosylceramides / Q000276:immunology; D015332:Gene Rearrangement, alpha-Chain T-Cell Antigen Receptor; D019337:Hematologic Neoplasms / Q000276:immunology / Q000473:pathology; D006801:Humans; D018664:Interleukin-12 / Q000494:pharmacology; D020382:Interleukin-18 / Q000494:pharmacology; D007694:Killer Cells, Natural / Q000187:drug effects / Q000276:immunology*; D008213:Lymphocyte Activation / Q000187:drug effects; D016853:Muromonab-CD3 / Q000494:pharmacology*; D014411:Neoplastic Stem Cells; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000235:genetics*; D016176:T-Lymphocyte Subsets / Q000187:drug effects / Q000276:immunology*; D014407:Tumor Cells, Cultured
D018949:Antigens, CD1; D055610:Antigens, CD1d; D000951:Antigens, Neoplasm; C526877:CD1D protein, human; D005699:Galactosylceramides; D020382:Interleukin-18; D016853:Muromonab-CD3; D016693:Receptors, Antigen, T-Cell, alpha-beta; D018664:Interleukin-12