On the other hand, weak immune responses have been generated in immunocompromised patients, including those with autoimmune disease (22, 23), solid organ transplant patients (24, 25), cancer patients treated with programmed cell death protein 1/programmed death-ligand 1 inhibitors or chemotherapy (26), patients with immune-mediated inflammatory disease (27), and patients with chronic lymphocytic leukemia or other hematological malignancies (28). Here, PDCD1 is linked to hematologic disorder.