LDHA-Associated Lactic Acid Production Blunts Tumor Immunosurveillance by T and NK Cells

Elevated lactate dehydrogenase A (LDHA) expression is associated with poor outcome in tumor patients. Here we show that LDHA-associated lactic acid accumulation in melanomas inhibits tumor surveillance by T and NK cells. In immunocompetent C57BL/6 mice, tumors with reduced lactic acid production (Ldhalow) developed significantly slower than control tumors and showed increased infiltration with IFN-γ-producing T and NK cells. However, in Rag2–/–γc–/– mice, lacking lymphocytes and NK cells, and in Ifng–/– mice, Ldhalow and control cells formed tumors at similar rates. Pathophysiological concentrations of lactic acid prevented upregulation of nuclear factor of activated T cells (NFAT) in T and NK cells, resulting in diminished IFN-γ production. Database analyses revealed negative correlations between LDHA expression and T cell activation markers in human melanoma patients. Our results demonstrate that lactic acid is a potent inhibitor of function and survival of T and NK cells leading to tumor immune escape. [Display omitted] •Human melanoma metastases exhibit a “Warburg phenotype” with high lactic acid levels•LDHA-associated lactic acid production and acidification lead to immune evasion•Lactic acid and acidification diminish NFAT levels and T and NK cell activation•LDHA expression in melanoma patients correlates with survival and T cell activity Brand et al. link altered tumor glucose metabolism and immune escape and show that increased lactic acid production by LDHA in cancer cells impairs cytokine production, in particular IFN-γ, in tumor-infiltrating T cells and NK cells, thereby inhibiting tumor immunosurveillance and promoting tumor growth.