Figure 8.

Increased immunogenicity of nucleosomes derived from apoptotic cells and involvement of TLR2 in the autoimmune response. (A) Groups of five BALB/c mice each were i.v. immunized three times with 50 μg of purified nucleosomes from viable and apoptotic Jurkat cells in intervals of 3 wk. A control group received PBS. Sera were collected before the first immunization and 3 wk after each immunization. Concentrations of IgG antibodies against nucleosomes, ssDNA, dsDNA, and histones were determined by ELISA. All sera were tested in the same assay. Mean values of the OD and SD are shown. Statistical analysis was performed using the nonparametric Mann-Whitney U test for unpaired samples. **, P ≤ 0.01; *, P ≤ 0.05. (B) To evaluate the requirement of TLR2 for the production of autoantibodies in vivo, groups of TLR2^−/−, TLR2/4^−/−, and C57BL/6 mice were i.v. injected with 75 μg of purified nucleosomes from apoptotic cells in intervals of 2 wk. 2 wk after the third immunization, anti-dsDNA and antihistone IgG antibodies were quantified in serum samples by ELISA. All sera were tested in the same assay. Bars indicate the mean values. Statistical analyses were performed using the Student's t test for unpaired samples. *, P ≤ 0.05.