Peroxiredoxin II Regulates Effector and Secondary Memory CD8<SUP>+</SUP> T Cell Responses

Reactive oxygen intermediates (ROI) generated in response to receptor stimulation play an important role in cellular responses. However, the effect of increased H ₂ O ₂ on an antigen-specific CD8 ⁺ T cell response was unknown. Following T cell receptor (TCR) stimulation, the expression and oxidation of peroxiredoxin II (PrdxII), a critical antioxidant enzyme, increased in CD8 ⁺ T cells. Deletion of PrdxII increased ROI, S phase entry, division, and death during in vitro division. During primary acute viral and bacterial infection, the number of effector CD8 ⁺ T cells in PrdxII-deficient mice was increased, while the number of memory cells were similar to those of the wild-type cells. Adoptive transfer of P14 TCR transgenic cells demonstrated that the increased expansion of effector cells was T cell autonomous. After rechallenge, effector CD8 ⁺ T cells in mutant animals were more skewed to memory phenotype than cells from wild-type mice, resulting in a larger secondary memory CD8 ⁺ T cell pool. During chronic viral infection, increased antigen-specific CD8 ⁺ T cells accumulated in the spleens of PrdxII mutant mice, causing mortality. These results demonstrate that PrdxII controls effector CD8 ⁺ T cell expansion, secondary memory generation, and immunopathology.