AGBL2 and Epstein-Barr virus infection: To exclude the possibility that we could not detect an IgG anti-CCP2 response in the kidney transplants patients because those patients receive immunosuppressive drugs that might interfere with the development of a mature antibody response, we compared anti-EBV antibody levels measured at the third time point (median 1 month after EBV infection, range 0–34 months) in serum of the kidney transplant patients with anti-EBV antibody levels detected in the non-immunosuppressed kidney donors (S1 Fig).