Fig 2.

B-cell precursors in aged bone marrow are resistant to cytokine-induced apoptosis. (A) Unfractionated bone marrow cells (1 × 10⁶ ml⁻¹) from young and aged ‘severely pre-B depleted’ (see Fig.1) B6 and BALB/c mice were cultured and IL-7 CFU determined. IL-7 CFU from young controls were set at 100%. (B) Bone marrow cells from young and aged mice were cultured with either 10 ng ml⁻¹ rmTNFα or 10 ng ml⁻¹ rmTGFβ in IL-7 CFU assays. IL-7 CFU for cultures not treated with TNFα or TGFβ were set to 100% for each group. Normalized IL-7 CFU values were obtained for 6–12 individual experiments for each group. Statistical significance (two-tailed Student's t-test): ***P = 0.0001; ****P < 0.0001.