The defect in B lymphopoiesis is cell autonomous.

<p>(A, D) Schematics of bone marrow transplants. Recipient mice received two doses of lethal irradiation (7+4.75 Gy) followed by intravenous injection of 5×10⁶ bone marrow cells. (B, E) Representative contour plots from flow cytometric analyses of B cells in the bone marrow 16 weeks post-transplant. Numbers indicate frequency of gated population for each genotype. (C, F) Frequency and absolute number of B cells in the bone marrow as determined by flow cytometry. <i>n</i> = 6–8 mice/genotype.