Fig. 3.

Loss of type 1, but not type 2, NF-κB activity blocks CD40-mediated proliferation of primary B cells. (A) Induction of G₁–S cell cycle transition genes. B cells from WT mice were stimulated with anti-CD40 mAb, hBAFF, or LPS. RNA was collected for analysis of c-Myc, CDK4, and cyclin D2 by Northern blot. (B) Contribution of type 1 NF-κBto c-Myc and cyclin D2 induction. WT (lane 1), p50^–/– (lane 2), c-Rel^–/– (lane 3), and p50^–/–c-Rel^–/– (lane 4) B cells were stimulated with medium (open bars), anti-CD40 (filled bars), and LPS (hatched bars) for 12 h. RNA was isolated for Q-PCR analysis of the indicated genes. (C) DNA synthesis. WT (solid lines in Upper and Lower), p52^–/– (broken lines in Upper), and p50^–/–c-Rel^–/– (broken lines in Lower) B cells were stimulated in triplicate with a 3-fold dilution series of anti-CD40 mAb (squares), hBAFF (circles), or LPS (triangles) for 48 h. The high dose of each ligand, labeled 6, was 45, 0.9, and 30 μg/ml for anti-CD40 mAb, hBAFF, and LPS, respectively. DNA synthesis was measured by addition of [³H]thymidine at 20 h poststimulation. Data represent the mean ± SD of two experiments.