PD-L1 gene expression is elevated in patients with active TB disease. Human gene expression of PD-1 and PD-L1 in whole-blood decrease during successful TB treatment. Infections with live M. tuberculosis upregulated PD-L1 expression on monocytes. In vitro PD-1 blocking rescued M. tuberculosis-specific IFN-γ-producing T cells from undergoing apoptosis. PD-1 blockade potentiates the specific degranulation of CD8+ T cells. The gene discussed is IFNG; the disease is tuberculosis.