Autoreactivity against TIMPs in blood and synovial fluid of patients with RA and in controls. Autoreactivity was measured as absorbance at 450 nm. White boxes, patients with RA, n = 89; coloured boxes, controls (blood n = 62, synovial fluid n = 21). The box plots represent the means and interquartile ranges in each group. The dashed line indicates the cut-off level for each type of TIMP equal to the mean +2 standard deviations of the controls. TIMP, tissue inhibitor of metalloproteinases.