Collagen-induced arthritis (CIA) in B6 and DBA/1 mice. Mice were immunised with type II collagen in complete Freund's adjuvant, and paw diameter (a) and clinical score (b) were measured for 120 days (n = 10 arthritic mice per group). (a) Paw swelling reached a peak in DBA/1 mice on day 30 and declined thereafter. In contrast, in B6 mice, paw swelling, although less pronounced, remained elevated up to day 120. **P < 0.01. (b) The clinical score was less in B6 CIA than DBA/1 CIA throughout most of the period studied. *P < 0.05.