Susceptibility to collagen-induced arthritis: cytokine-mediated regulation

Collagen-induced arthritis is an animal model of inflammatory polyarthritis that is induced in susceptible strains of rats and mice by intradermal immunization with heterologous type II collagen emulsified in complete Freund's adjuvant. Previous studies have demonstrated that disease induction is highly MHC-restricted, with only mice of H-2(q) or H-2(r) haplotypes being susceptible. We have used a panel of both susceptible and resistant strains of mice in which either IFN-gamma or IL-10 signaling has been abolished by gene deletion and show that disease can be readily induced in several resistant strains of the H-2(b) and H-2(d) haplotype; susceptibility was highly dependent on IL-12. IL-4 was also shown to be crucial for disease induction in this model. These results suggest that both Th1 and Th2 cytokines may be important in the etiopathogenesis of disease and that disease susceptibility may be a function of a dysregulated cytokine environment.