PDCD1 and angioimmunoblastic T-cell lymphoma: Neoplastic cells of AITL are thought to originate from the monoclonal expansion of follicular helper T cells (TFHs) [3, 4], manifesting as CD4+CD8- T-cell receptor (TCR) α/β cells that express CXCL13, CD10, BCL6, PD-1, and ICOS [2, 5–8].