% SELF ANTIGEN BK AII VEGF bFGF Reproducibility 96 97 90 90 Sensitivity         primary kOA 26 13 23 8 secondary kOA 17 8 5 3 Specificity 96 95 93 91

Table 2: Reproducibility, sensitivity and specificity of detection of natural IgG antibodies in osteoarthritis of the knee.