Fig. 3.

Anti-CarP antibodies and ACPA are two separate autoantibody systems. (A) IgG reactivity of 76 sera from RA patients, toward several forms of a Fib peptide is depicted. (B and C) Antibody binding to Ca-FCS or Ci-FCS was inhibited using preincubations with fluid-phase inhibitors. (D) FCS, Ca-FCS, and Ci-FCS were separated by SDS-PAGE gels and blotted. The presence of antibodies reactive to proteins on the blots was analyzed by incubating these blots with either anti-CarP–positive ACPA-negative and anti-CarP–negative ACPA-positive sera.