Immunomodulatory therapies can effectively control haematological malignancies by promoting anti-tumour immunity. Previously we reported transient control growth of poorly immunogenic murine non-Hodgkin B cell lymphomas (B-NHL) by targeting natural killer T (NKT) cells with a therapeutic vaccine approach. Therapeutic efficacy was highly dependent on the ability of the vaccine to provoke rapid IFNγ production from NKT and NK cells. By manipulating the capacity of either host or lymphoma cells to signal through the IFNγ receptor (IFNγR) we investigated whether the therapeutic effect conferred by vaccine-induced IFNγ is a result of immune cell activation, lymphoma IFNγ sensitivity, or a combination of both. We demonstrated that anti-tumor immunity elicited by vaccination requires IFNγ-signalling within host cells, but not tumor cells. IFNγR deficient mice failed to mount an effective anti-tumor immune response following vaccination despite elevated IFNγ levels. With successive exposure to vaccination, lymphomas acquired an increasingly therapy-resistant phenotype and displayed a reduction in MHCI and CD1d surface expression, which is independent of tumor intrinsic IFNγ-signalling. Our results suggest that immunotherapy-induced IFNγ production mainly exerts its therapeutic effect via signalling through host cells, rather than directly to tumor cells in B-NHL. This signifies that intact IFNγ signalling within patients' immune compartment rather than tumor cell sensitivity to IFNγ is more critical for successful treatment. Finally, tumor IFNγ-signalling alone does not drive acquired tumor resistance to vaccination, implying that additional immunoediting pathways are responsible tumour immune escape.Immunology and Cell Biology accepted article preview online, 20 January 2016. doi:10.1038/icb.2016.9.