Fig. 6.

Enhanced B cell proliferation and expansion of MZ B cells. (A) B and T cells purified from spleens of WT and GAPT^−/− mice were incubated with medium (–), anti-IgM F(ab′)₂, anti-CD40, and LPS or anti-CD3 and PMA plus ionomycin (P+I), respectively, for 48 h. Proliferating cells were then examined by measuring [³H] thymidine incorporation. Experiments were performed in triplicate, and figures represent three independent experiments with similar results. Left panel, B cells were stimulated by anti-IgM at 10 μg/ml; right panel, B cells were stimulated by anti-IgM at different concentrations shown in the figure. (B) The absolute numbers of total T cells, B cells, and B cell subsets per mouse spleen. (C) Percentages of MZ B cells in WT and GAPT^−/− mice. MZ B cells were characterized as CD23⁻CD21⁺B220⁺ cells. Figure also shows the increased percentage of MZ and T2 B cells as a result of increased MZ B cell percentage. (D) Concentrations of circulating serum Ig isotypes in aged GAPT^−/− mice. *, P < 0.05; **, P < 0.01.