The present work presents evidence that a progressively growing, endogenous tumor indeed fails to activate NK-cell effector functions. Escape from NK-cell surveillance seems

to be more complex than the hypothesis of failing priming or failing triggering might suggest. Possibly, NK cells are exhausted as a consequence of prolonged activation, as it was described for T cells 44. Alternately, developing tumors might actively paralyze NK cells. These observations should be considered when establishing, e.g. approaches Cobimetinib manufacturer of adoptive NK-cell transfer. All cell lines were cultured in RPMI 1640 (Invitrogen, Karlsruhe, Germany) medium supplemented with 5% heat-inactivated FBS, 2 mM L-Glutamine, 100 U/mL penicillin and streptomycin, non essential aa, and 50 μM 2-ME. Cells were kept

at 37°C in a humidified 5% CO2 atmosphere. A20 and MPC11 are BALB/c-derived B-cell lymphoma cell lines 45, 46. The variant A20low expressing reduced levels of MHC class I was generated by transfection of A20 with an mCMV-derived gene 6. The murine lymphoma cell line YAC-1 served as a target for NK-cell killing in cytotoxicity assays 47. DC were generated exactly as previously described 22. λ-myc cell lines myc-B, myc-E and 291S were generated by seeding primary lymphoma cells from λ-myc mice on irradiated MRC-5 fibroblasts as a feeding layer. After about 2 wk of culture, cells were able INCB024360 concentration to grow independently. All animals were kept under specific pathogen-free conditions in our animal facility. C57BL/6 and BALB/c WT mice were purchased from Bommice (Ry, Denmark). λ-myc mice 29 are of C57BL/6 origin and were bred in our own facility. All animal experiments were in accordance with relevant regulations and had been approved by the Regierung von Oberbayern. Groups of at least six age-matched mice were used for experiments. Animals were treated with 10 nMol

CpG-ODN 1668 (Metabion, Martinsried, Germany) that was injected i.p. in 1- to 2-wk intervals 6 or received 5×105 DC subcutaneously as described earlier 22. NK-cell depletion was done by using anti-asialo GM1 Ab (Wako, Neuβ, Germany). 100–300 μL were administered i.v. and i.p. 1 day before each CpG-ODN injection Florfenicol in λ-myc mice; 300 μL were given i.p. 1 day before as well as 2 and 9 days after challenge with myc-B tumor cells in WT mice. NKT cells were not affected by treatment with anti-asialo GM1. In total, 104 to 105 myc-B, myc-E, 291S or MPC11 cells or 106 A20 or A20low cells were injected i.v. Phenotyping of NK cells was done by labeling with the following mAb: CD49b (DX5, BD Pharmingen, Heidelberg, Germany), CD45R (RA3-6B2, BD Pharmingen), NKG2D (CX5, eBioscience, San Diego, USA), Ly49D (4E5, BD Pharmingen), Ly49I (YLI-90, BD Pharmingen), CD69 (H1.