PDCD1 and systemic lupus erythematosus: Previous reports on peripheral CD8+ T cells in SLE include several reports on enhanced CD8+ T cell function29, 31 as well as impaired CD8+ T cell function due to increased CD38 expression or metabolic abnormalities.32, 35 In this study, activated CD8+ T cells showed no evidence of exhaustion, such as reduced cytotoxic capacity or inflammatory cytokine production (cell surface components, such as programmed cell death protein-1 and cytotoxic T lymphocyte-associated protein-4, were not assessed).