A positive correlation was obtained between FLC concentrations and SLEDAI scores for high CRP SLE patients (SLEDAI range: 0–21, median: 4) (Fig 8A) (r-values of 0.506 (p = 0.004), 0.500 (p = 0.005) and 0.453 (p = 0.012), regarding concentrations of total FLC, λFLC and κFLC, respectively), but not between FLC concentrations and SLEDAI scores for low CRP SLE patients (SLEDAI range: 0–12, median: 4) (Fig 8B) (r-values of 0.246 (p = 0.378), 0.393 (p = 0.148) and -0.056 (p = 0.844), regarding concentrations of total FLC, λFLC and κFLC, respectively). Here, CRP is linked to systemic lupus erythematosus.