TNF and neoplasm: NK cells and CD8+T cells participate in tumour progression by secreting cytokines such as interferon- (IFN-) γ and tumour necrosis factor- (TNF-) α. To explore whether the microbiota affects the secretion of cytokines from pulmonary NK cells and CD8+T cells, we also measured IFN-γ and TNF-α secretion in the four groups of mice at stages 1 and 3.