Summary of clinical arthritis and histological scores of immunized mice. (a) Groups of mice with different genotypes were immunized with arthrogenic antibodies on day 0, followed by LPS on day 3. Each paw was evaluated and scored on a scale of 0–3, as outlined in Methods. Results are expressed as the mean arthritis score on day 7 of all four paws (maximum score of 12 per mouse). Joint sections were evaluated by a blinded observer for cellular infiltrate (b), severity of joint exudate (c), and proteoglycan (PG) depletion(d). Degree of proteoglycan depletion was scored on a scale of 0–3 with 3 being most severe. Results are expressed as mean ± SEM for each of the histological features, quantified in WT, DPPI–/–, NE–/– × CG–/–, NE–/–, and CG–/– mice (n = at least four animals and 16 paws per genotype). *P < 0.01, **P < 0.001.