Cystatin C-deficient mice have a higher incidence of arthritis but have a similar arthritic score. A, Cystatin C-deficient mice (Cyst C-/-, n = 17) had a greater cumulated arthritis incidence (that is, all mice that have shown signs of arthritis at any time point are included as diseased individuals) compared to heterozygous (Cyst C-/+, n = 23) and wild type litters Cyst C+/+, n = 9). Data shown are from one representative experiment out of two separate experiments (combined data shown in Table 1). * P-value < 0.05 as tested in Fisher's exact test. B, Cystatin C-deficient mice (n = 15) had a similar arthritic severity compared to heterozygous (n = 17) and wild type littermate controls (n = 5) when affected mice were compared (mice were excluded if no clinical signs of arthritis was seen after 115 days post immunization).