Blockade of the PD-1/PD-L1 pathway is reported to increase the production of Th1 cytokines,22, 31 and a recent study examining correlates of response to a different PD-L1 antibody (MPDL3280A) found that a tumor environment with a Th1 orientation (measured by gene expression) was associated with favorable clinical outcome.32 It has also been reported that the addition of a PD-1-blocking antibody to a stimulation assay of PBMCs from cancer patients decreased Th2 cytokines (for example, IL5 and IL13);33 however, those effects were not noted in HDs. The gene discussed is IL13; the disease is cancer.