Loss of miR-221/222 does not alter B cell development in the bone marrow or spleen, and steady-state serum antibody levels are unaffected. (A) Representative flow cytometry gating strategy for bone marrow analysis. Upper left gate is a subgate of live, singlet, CD19⁺, B220⁺ cells. Further subsetting by B220^int, CD43⁺, CD24⁺, IgM⁻ pro-B cells; B220^int, CD43^int, CD24⁺, IgM⁻ pre-B cells; B220^int, CD24⁺, IgM^hi, IgD⁻ immature B cells; and B220^hi, IgM^int, IgD⁺, CD24^lo mature cells. (B) Enumeration of percentage and number of each developmental bone marrow subset determined in A. (C) Representative flow cytometry gating strategy for splenic analysis. Leftmost plot is pregated on live, singlet, B220⁺, CD4⁻ cells that are subdivided into transitional CD93⁺ subsets CD23⁻, IgM^hi T1; CD23⁺, IgM^hi T2; and CD23⁺, IgM^lo T3 or into mature CD93⁻ subsets CD23⁺, CD21^int follicular and CD23^lo, CD21^hi marginal zone B cells. (D) Enumeration of percentage and number of each developmental splenic subset determined in C. (E) Steady-state serum concentrations for the labeled isotypes in flox and Δ mice. All P values were derived from a two-tailed Student’s t test; P > 0.05 for all unlabeled comparisons; *, P < 0.05. Representative experimental data of two independent experiments with at least four mice per genotype.