CD8A and rheumatoid arthritis: A similar GZMBloGZMKhi CD8 population was identified in the synovial fluid in rheumatoid arthritis, having lower cytotoxic potential than the GZMBhi CD8 T cells in the blood, and was able to drive reactive oxygen species (ROS) and inflammatory cytokine production of fibroblasts in vitro.48 This non-canonical cytotoxicity profile suggests that instead of inducing apoptosis, ocular CD8 T cells might play a role in initiating or sustaining the inflammatory tone in uveitis.