Human TCR-αβ+ CD4− CD8− T Cells Can Derive from CD8+ T Cells and Display an Inflammatory Effector Phenotype

The origin and function of human double negative (DN) TCR-alphabeta+ T cells is unknown. They are thought to contribute to the pathogenesis of systemic lupus erythematosus because they expand and accumulate in inflamed organs. In this study, we provide evidence that human TCR-alphabeta+ CD4- CD8- DN T cells can derive from activated CD8+ T cells. Freshly isolated TCR-alphabeta+ DN T cells display a distinct gene expression and cytokine production profile. DN cells isolated from peripheral blood as well as DN cells derived in vitro from CD8+ T cells produce a defined array of proinflammatory mediators that includes IL-1beta, IL-17, IFN-gamma, CXCL3, and CXCL2. These results indicate that, upon activation, CD8+ T cells have the capacity to acquire a distinct phenotype that grants them inflammatory capacity.