For RA patients, by administrating etanercept (a TNF-alpha inhibitor), the serum level of IL-33 significantly decreased at 3 and 6 months, and serum IL-33 levels showed a significant correlation with the number of tender joints, C-reactive protein, Disease Activity Core of 28 joints including CRP and the WBC count, and an inverse correlation with the RBC count and hemoglobin level [44]. This evidence concerns the gene TNF and rheumatoid arthritis.