CD274 and infection: In CHB patients, PD-1 on total CD8 T cells in PBMCs and PD-L1 expression in liver are variable depending on the stage of infection and age of the patient, suggesting that some, but not all patients may have PD-1/PD-L1 pathway dependent activity required for responses to PD-L1 blockade [15,17–20,34,35].