Fig. 1.

Excess CD40L induces autoantibody production in 56R mice without perturbing clonal deletion in bone marrow. Anti-DNA antibody H chain-Tg mice 3H9 and 56R mice on the BALB/c background were each crossed with CD40L Tg mice on the C57BL/6 background to generate F1 mice. (A) Sera were obtained from 8- to 15-wk-old F1 mice, and the titers of IgM anti-DNA antibodies (Left) and total serum IgM (Right) were measured by ELISA. Numbers of mice that were analyzed are indicated in parentheses. The titer of anti-DNA antibodies was determined by ELISA relative to a standard curve of DNA binding of anti-DNA monoclonal antibody BW28-20-1 derived from NZB/W F1 mice (IgM; a gift from Hirose, Juntendo University, Tokyo, Japan). Horizontal bars represent mean values. NS, not significant. (B) Bone marrow cells were obtained from 8- to 15-wk-old F1 mice and stained for B220 and IgM expression. Cells in the lymphocyte gate were analyzed by flow cytometry as described previously (50), and percentages of pro/pre B cells, immature B cells, transitional B cells, and mature B cells in lymphocyte-gated cells were calculated. Representative data of three experiments are shown.