Lactate Potentiates Differentiation and Expansion of Cytotoxic T Cells

Exercise has a wide range of systemic effects. In animal models, repeated exertion reduces malignant tumor progression, and clinically, exercise can improve outcome for cancer patients. The etiology of the effect of exercise on tumor progression is unclear, as are the cellular actors involved. We show here that exercise-induced reduction in tumor growth is dependent on CD8+ T cells and that lactate, which is produced at high levels during exertion, increases proliferative capacity and cytotoxicity of CD8+ T cells. We found that at elevated levels lactate is used as a fuel during T cell activation. We further found that daily injections of lactate into animals can reduce malignant tumor growth in a dose- and CD8+ T cell-dependent manner. These data demonstrate that lactate can act to enhance expansion of cytotoxic T cells and in so doing reduce cancer progression.