Combining a transcriptional-based approach to predict tumor antigen reactivity with experimental confirmation of antigen specificity, we identify a subpopulation of tumor antigen-specific CD8+ T cells which are shared between tumor and blood and resemble KIR+CD8+ regulatory T cells (Tregs) recently described to have a role in regulating autoinflammatory responses2,3. This evidence concerns the gene KIR3DL1 and neoplasm.