Autoantibodies in plasma. Plasma samples were collected and autoantibody levels were measured as described in the Material and Methods section using samples collected at 24 weeks and compared with four different pools of pre-disease six-week-old mice. Antibody levels for SSA/Ro (A) SSB/La (B) and ANA (C) are shown (mean ± SD). Significant differences are indicated (*) and were determined by one-way ANOVA test followed by unpaired student's t-test. LacZ (N = 8) and TNFR1:IgG (N = 6).