Figure 4.

B cells derived from the 1–82 mice behave as mature cells. (A) Adult control Ii^−/− or 1–82 mice were fed BrdUrd in their drinking water for 3 days. Splenic B cells were analyzed for their BrdUrd incorporation. Histograms represent BrdUrd labeling of B220⁺-gated spleen cells. Numbers represent percentage of BrdUrd-positive cells. The results presented are representative of three different experiments. (B) LN cells from control, Ii^−/−, and 1–82 mice were double-stained with anti-B220 and anti-CD8. Dot plots show the CD8 and B220 populations in the various mice. The results presented are representative of three different experiments. (C) Wild-type B cells (B con), immature B cells from Ii^−/− mice (B ^−/−Ii), or 1–82-derived B cells were labeled with ⁵¹Cr, washed, resuspended in adhesion medium, and added to fibronectin-coated wells in the presence of phorbol 12-myristate 13-acetate or SDF-1 stimulation. The adherent cells were lysed, and radioactivity was determined. One experiment representative of four is depicted. (D) B cells purified from C57BL/6 (B6) Ii^−/− and 1–82 transgenic mice were cultured in the presence of elevated concentrations of anti-IgM. Proliferation was determined by the addition of 1 μCi of [³H]thymidine for the last 18 h of a 2-day culture. One experiment representative of three is depicted.