CD8A and rheumatoid arthritis: Specifically, RA was causally linked to a decreased level of CD3 on activated CD4 regulatory T cell (IVW beta: -0.10, 95% CI: -0.18, -0.01, p = 0.021) and increased CD25++ CD8+ T cell % CD8+ T cell (IVW beta: 0.11, 95% CI: 0.03-0.19, p = 0.006), while genetically predicted MS was significantly associated with higher expression of CD127 on granulocyte (IVW beta: 0.11, 95% CI: 0.04-0.17, p = 0.002) (Supplementary Table 6).