The condition disappeared a few days after discontinuation of IFN.12 Seropositive polyarthritis with high erythrocyte sedimentation rate (ESR), elevated C-reactive protein (CRP), and high rheumatic factor (RF) titer was reported in a 42-year-old woman with RRMS after 30 months of treatment with INF-β1b.12 Animal experiments have shown that GA could exacerbate autoimmune arthritis. Here, CRP is linked to polyarticular arthritis.