MASP2 gene deficient (MASP2‐/‐) mice treated with bovine collagen type II protected arthritis induction, evidenced by reduced clinical disease activity, decreased histopathological scores, C3 deposition and infiltration of synovial macrophages, neutrophils, whereas the wild‐type mice showed severe features of arthritis.18 Here, MASP2 is linked to arthritic joint disease.