Dysregulated immune features in a patient with a homozygous loss-of-function mutation in PDCD1 suggest that IL-6, IL-23, STAT3 and ROR gamma T might be potential targets for treatment of PD-1 blockade-induced autoimmunity.The pathophysiology of adverse events following programmed cell death protein 1 (PD-1) blockade, including tuberculosis (TB) and autoimmunity, remains poorly characterized. We studied a patient with inherited PD-1 deficiency and TB who died of pulmonary autoimmunity. The patient's leukocytes did not express PD-1 or respond to PD-1-mediated suppression. The patient's lymphocytes produced only small amounts of interferon (IFN)-gamma upon mycobacterial stimuli, similarly to patients with inborn errors of IFN-gamma production who are vulnerable to TB. This phenotype resulted from a combined depletion of V delta 2(+) gamma delta T, mucosal-associated invariant T and CD56(bright) natural killer lymphocytes and dysfunction of other T lymphocyte subsets. Moreover, the patient displayed hepatosplenomegaly and an expansion of total, activated and ROR gamma T+ CD4(-)CD8(-) double-negative alpha beta T cells, similar to patients with STAT3 gain-of-function mutations who display lymphoproliferative autoimmunity. This phenotype resulted from excessive amounts of STAT3-activating cytokines interleukin (IL)-6 and IL-23 produced by activated T lymphocytes and monocytes, and the STAT3-dependent expression of ROR gamma T by activated T lymphocytes. Our work highlights the indispensable role of human PD-1 in governing both antimycobacterial immunity and self-tolerance, while identifying potentially actionable molecular targets for the diagnostic and therapeutic management of TB and autoimmunity in patients on PD-1 blockade.