In hematological malignancies, BTLA/HVEM axis dysregulation decreased perforin and granzyme B production by BTLA+ T cells and was associated with poor outcome in DLBCL and FL, whereas only two studies reported about BTLA and HVEM expression on leukemic cells from CLL [42,51,55]. This evidence concerns the gene PRF1 and diffuse large B-cell lymphoma.