Impaired IL-7 response of the BM BLPs from mb.1-Rap1A17 Tg mice. (A) BM cells from Rap1A17^f (solid line) and mb.1-Rap1A17 (fine dotted line) Tg mice were 3-color stained with anti-B220, anti-CD25, and anti–IL-7α antibodies and analyzed with FACSCalibur. IL-7Rα–staining profiles in a B220⁺ CD25⁺ gate are indicated. The course dotted line indicates the control staining. (B) The B220⁺ BM cells from Rap1A17^f (○) and mb.1-Rap1A17 Tg (●) mice were cultured in the presence (solid lines) or absence (dotted lines) of IL-7 (10 ng/mL), and B220⁺ cell numbers were determined at the indicated days (left). In independent experiments, the cells were cultured in the presence of various doses of IL-7 (0 ∼ 25 ng/mL) for 6 days (right). The mean percentages and SEs of the viable B220⁺ cell recoveries in triplicate cultures are indicated. *P < .05; **P < .01. (C) The aliquot cells of the cultures (IL-7 at 10 ng/mL) were multicolor analyzed with the indicated antibodies. The percentages of cells in the quadrants are indicated. (D) B220⁺ cells sorted from the BM of normal B6 and Rag2^−/− mice were infected with empty (□) or Rap1A17-containing (■) MIG and cultured in the presence of IL-7 (10 ng/mL). On days 1 and 5, the numbers of GFP⁺ B220⁺ cells were determined. The means and SEs of triplicate cultures are indicated.