KLRB1 and rheumatoid arthritis: Peripheral RA MAIT cells were mostly CD4+ (controls 8.3%, SpA 12.3%, RA 52.6%; p < 0.001) and CD161 expression was strongly reduced (control mean fluorescence intensity (MFI) = 2348, SpA MFI = 2219, RA MFI = 226; p < 0.001).