IFNG and neoplasm: The current understanding of the dichotomous nature of immune cells in tumours is that IFN-γ-producing CD4+ T helper (Th) 1 and CD8+ T lymphocytes, along with mature dendritic cells (DCs), NK cells, M1 macrophages, and type 1 NK T-cells can generate anti-tumour responses; and conversely, CD4+ Th2 cells, CD4+ T regulatory (Treg) and type 2 NK T-cells, MDSC, immature DCs, or alternatively activated (M2) macrophages promote tumour tolerance and support tumour growth and progression (Gobert et al. 2009, Ruffell et al. 2010, Zamarron & Chen 2011, Emens 2012).