Specific antibody responses to recombinant collagen type II peptides in chronic and acute collagen-induced arthritis. (A) Chronic arthritis in male mice from B10.Q × (BALB/c × B10.Q) N2 mice (n = 10). Clinical arthritis is denoted on the right y axis: straight lines, mean arthritis score; dashed grey lines, mean + standard error the mean. Scoring of the mice was performed until day 201. The left y axis shows percent responders to the overlapping recombinant collagen type (rCII) peptides in sera from chronic collagen-induced arthritis (CIA) mice at day 35 (onset), day 80 (early-chronic disease), and day 210 (late-chronic disease). (B) rCII peptides detected in ≥50% of the mice are included. (C), (D), (E) Autoantibody recognition of rCII peptides in chronic CIA: dotted lines, cutoff calculated as the mean ± three standard deviations of naïve mice. Numbers above the bars correspond to the rCII peptides in the library followed by the epitope name in brackets for B-cell epitopes identified earlier. (F) CIA development in B10.Q male mice depicted as the mean arthritis score + standard error of the mean. (G) Sera from the acute CIA mice, collected on day 50, were also tested for specificity to the rCII peptides.