The lack of detection of this PTLC subtype in our adoptive transfer experiments is still unclear, although it might reflect the need of cooperating genetic events that could favor the emergence of a T cell subtype different from the TFH phenotype characteristic of AITL (e.g., viral integrations in the case of adult T cell leukemia/lymphoma [ATLL], loss of TP53 and/or TET2 genes in AITL) [36,37,38]. Here, TET2 is linked to adult T-cell leukemia/lymphoma.