All 28 AITL cases with tissue biopsy showed CD3 and PD-1 immunoreactivity by immunohistochemistry, and PD-1 expression on abnormal T-cells by flow cytometry showed excellent correlation with immunohistochemistry (Supplementary Table 2, Fig. 2a–i). This evidence concerns the gene PDCD1 and angioimmunoblastic T-cell lymphoma.