Figure 2: iGB cells differentiate into cells with a B_mem phenotype in recipient mice.

(a) Day 4 iGB cells derived from C57BL/6 Ly5.1⁺ congenic mice (2×10⁷) were purified and transferred i.v. into γ-irradiated (6.5 Gy) C57BL/6 mice (Ly5.2⁺). Eight weeks later, pooled spleens of four recipients and a spleen of an untreated C57BL/6 mouse were stained with the indicated antibodies and analysed by flow cytometry. Ly5.1⁺ CD19⁺ donor and Ly5.1⁻ CD19⁺ recipient B cells were gated as indicated and analysed for their BCR isotypes. (b) Expression of the indicated markers on the donor IgG1⁺ (Ly5.1⁺ CD19⁺ IgD⁻: red line) or IgM/D⁺ (Ly5.1⁺ CD19⁺ IgD⁺: blue line) iMB cells and the recipient naïve B cells (Ly5.1⁻ CD19⁺ IgD⁺: shaded) shown in (a) were analysed. Anti-mouse IgG1 Ab was not used because it often cross-reacts with rat antibodies. The data shown are representative of three independent experiments performed with three to four mice per group. (c) Expression levels of B7.1 and Fas on Ly5.1⁺ iMB cells (closed circles; n=8) or Ly5.1⁻ naïve B cells from the recipient and two normal C57BL/6 mice (open circles; n=10). Plotted are geometric means (geomean) of the fluorescence intensity of the cells from individual mice with the average value of each group of mice indicated by a horizontal line.