Fig. 2

Shift in CD4⁺/CD8⁺ MAIT cell subsets and low CD161 expression in early, untreated RA patients. a MAIT cells divided based on CD4 and CD8 expression. Whereas MAIT cells are generally mostly CD8⁺, in early RA patients most MAIT cells are CD4⁺, indicating a shift within the MAIT cell population. Median double-negative MAIT cells (DN): controls 12.8%, SpA 21.2%, RA 11.2%. Median CD4⁺ MAIT cells: controls 8.4%, SpA 12.3%, RA 52.6%. Median CD8⁺ MAIT cells: controls 70.3%, SpA 56.8%, RA 32.6%. b CD161 expression lower in early RA patients compared to controls and SpA patients, both ex vivo and upon stimulation (based on MFI). Median CD161 MFI unstimulated MAIT cells: controls 2348, SpA 2219, RA 226. Median MFI upon stimulation: controls 2134, SpA 1844, RA 482.5. **p ≤ 0.01; ***p ≤ 0.001. MAIT mucosal-associated invariant T, MFI mean fluorescence intensity, RA rheumatoid arthritis, SpA spondyloarthritis