We found that the activation markers, CD69 (35.0 ± 32.0% vs. 11.4 ± 11.2%, p < 0.01) and CD38 (12.9 ± 16.7% vs. 1.7 ± 1.6%, p < 0.05), were upregulated in MAIT cells from patients with PBC compared to those from HCs (Figure 2A, Supplementary Figure 2) with the stimulation of anti-CD3 and anti-CD28 antibodies, suggesting that MAIT cells from patients with PBC were over-activated. This evidence concerns the gene CD28 and primary biliary cholangitis.