IL1R1 and rheumatoid arthritis: Percentages of these IL-1R1+ Th17 cells were only significantly increased in PsA patients (mean 4.40%, SEM 1.13%) compared with HCs (mean 1.78%, SEM 0.25%; p < 0.01, Figure 2D), but not in axSpA (mean 1.60%, SEM 0.23%) and RA (mean 1.69%, SEM 0.35%) patients.