IL-2Rα is not essential for MZ B-cell development in a noninflamed environment. Mixed bone marrow chimeras were generated by reconstitution of irradiated WT C57BL/6 mice (CD45.1) with a 1:1 mixture of bone marrow cells of WT (CD45.1) and il2ra^−/− (CD45.2) or WT (CD45.1) and DKO (CD45.2) mice. Two months later, the spleen was removed, and the isolated cells were analyzed by flow cytometry. (A) Cells were stained with anti-CD21, anti-CD23, anti-CD19, and anti-CD45.2 or CD45.1 monoclonal antibodies. Representative dot plots of individual samples show CD21 and CD23 expression gated on CD19⁺ CD45.2⁺ B cells (top panel) or CD19⁺ CD45.1⁺ B cells (bottom panel). (B) Shown is ratio of knockout (CD45.2) versus WT (CD45.1) CD21⁺CD23⁻ MZ B cells among CD19⁺ cells. Values indicate averages ± SEM of 4 mice per group. (C) Percentages of FoxP3⁺ regulatory T cells among CD4⁺ cells. Symbols indicate individual mice. Notably, more than 90% of the Tregs in the chimera were derived from CD45.1 WT bone marrow (data not shown). (D) CD44 and CD62L expression on cells gated on CD4⁺ and CD45.2⁺. Shown are dot plots of individual samples representative of a group of mice.