Electron transport complex I is required for CD8+ T cell function

After Ag encounter, CD8(+) T cells become activated and begin to proliferate. Early during infection, when Ag-specific effector CD8(+) T cells are proliferating, producing cytokines, and lysing infected cells in vivo, their mitochondrial potential is increased. The purpose of the experiments presented here was to determine whether mitochondrial function was required for CD8(+) T cell function. To block mitochondrial function, transgenic CD8(+) T cells were incubated with increasing doses of rotenone, an inhibitor of electron transport complex I. Within minutes of T cell activation, rotenone incubation decreased the production of H2O2, calcium flux, and ERK1/2 phosphorylation. Failure to undergo signal transduction resulted in a decrease in T cell division initiated by peptide-coated cells, CD3/CD28 Abs, and PMA/ionomycin stimulation. Decreased function following roitenone incubation was not restricted to naive cells, as effector and memory CD8(+) T cells isolated directly ex vivo from lymphocytic choriomeningitis virus-infected mice displayed decreased production of IFN-gamma and TNF-alpha production after peptide stimulation. Furthermore, incubation with rotenone decreased degranulation of effector and memory cells, a critical step in the cytolysis of infected cells. These data suggest that electron transport complex I is required for CD8(+) T cell signal transduction, proliferation, cytokine production, and degranulation.