Transduction with the antioxidant enzyme catalase protects human T cells against oxidative stress.

Patients with diseases characterized by chronic inflammation, caused by infection or cancer, have T cells and NK cells with impaired function. The underlying molecular mechanisms are diverse, but one of the major mediators in this immune suppression is oxidative stress caused by activated monocytes, granulocytes, or myeloid-derived suppressor cells. Reactive oxygen species can seriously hamper the efficacy of active immunotherapy and adoptive transfer of T and NK cells into patients. In this study, we have evaluated whether enhanced expression of the antioxidant enzyme catalase in human T cells can protect them against reactive oxygen species. Human CD4(+) and CD8(+) T cells retrovirally transduced with the catalase gene had increased intracellular expression and activity of catalase. Catalase transduction made CD4(+) T cells less sensitive to H(2)O(2)-induced loss-of-function, measured by their cytokine production and ability to expand in vitro following anti-CD3 stimulation. It also enhanced the resistance to oxidative stress-induced cell death after coculture with activated granulocytes, exposure to the oxidized lipid 4-hydroxynonenal, or H(2)O(2). Expression of catalase by CMV-specific CD8(+) T cells saved cells from cell death and improved their capacity to recognize CMV peptide-loaded target cells when exposed to H(2)O(2). These findings indicate that catalase-transduced T cells potentially are more efficacious for the immunotherapy of patients with advanced cancer or chronic viral infections.