Autoantibodies to murine type II collagen in collagen-induced arthritis: a comparison of susceptible and nonsusceptible strains.

Collagen-induced arthritis (CIA) is an experimental autoimmune disease elicited in genetically susceptible strains of mice by immunization with heterologous type II collagen. This experimental disease is mediated by the immune response of both T cells and B cells, and susceptibility is restricted by the class II molecules of the MHC. In this study we identify specific epitopes bound by autoantibodies elicited through immunization of several haplotypes of C57BL/10 mice with chick alpha1 (II)-CB11. ELISA analysis using a panel of 15-mer murine type II collagen peptides revealed a pattern of autoantibody epitope specificity that was remarkably similar among CIA-susceptible and nonsusceptible congenic strains, regardless of class II haplotype. However, one epitope was identified that was bound only by autoantibodies from CIA-susceptible strains bearing I-A(q) (B10.Q and B10.QbetaBR). In addition, this epitope was also present within affinity-purified Ab obtained from the CIA-susceptible strain DBA/1 (I-A(q)). Analyses of immune serum from B10.Q and B10.QbetaBR mice revealed that a subset of the antibodies binding this epitope were of the IgG2 subclass, and therefore efficient at fixing complement, a requirement for pathogenicity of the Abs in CIA.