PDCD1 and leprosy: In the immunosuppressive environment like leprosy, upregulation of inhibitory molecules such as cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4) and programmed cell death-1 (PD-1) on T cells and their ligands on APCs which resemble T-cell anergy and exhaustion in leprosy patients (4, 22).