In addition, serum IL-33 levels in SLE patients were significantly higher than those in healthy subjects, which are thought to be closely related to IgA, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP), speculating that IL-33 may be part of the acute phase response, even if it is not related to SLE activity [18]. Here, CRP is linked to systemic lupus erythematosus.