CCR9 and rheumatoid arthritis: In immune-mediated diseases like primary Sjögren’s syndrome (pSS) (56), primary biliary cholangitis (PBC) (57), inflammatory bowel disease (IBD) (58–61), rheumatoid arthritis (RA) (62), and type 1 diabetes (T1D) (63–65), the chemokine and cytokine milieu in inflamed tissues drives MAIT cell via various chemokine receptors such as CCR9, CXCR5, CXCR4, CXCR3, CCR6, and CCR10 (Figure 1).