Furthermore, in a recently published study ACPA IgA was identified as a risk factor for disease flare during drug tapering in patients with RA (25) and there is now emerging eveidence that IgA autoantibodies, and particularly the IgA2 subclass, contribute to the inflammatory processes of RA by activating macrophages and neutrophils (26). Here, PRTN3 is linked to rheumatoid arthritis.