This assumption is further supported by the correlation analysis between sHLA-G levels and LILRB1 recognition: Although a significant positive correlation between sHLA-G level and LILRB1 recognition was found in both healthy controls (r = 0.57, p = 0.003) and RA patients (r = 0.52, p < 0.001), the correlation did differ with respect to the slope of their linear regression line (Fig 3): For healthy controls the slope of regression line was with 4.43 ± 2.2 steeply rising, whereas for RA patients the slope of regression line was with 0.96 ± 0.18, clearly decreased. Here, LILRB1 is linked to rheumatoid arthritis.