Altered B-cell differentiation in CD19Tln1^−/− mice. (A) Top left: FACS analysis of B220⁺ BM cells from WT or CD19Tln1^−/− mice stained with anti-AA4 and anti-IgM mAbs, depicting pre-pro (P.), immature (I.), and mature (M.) B-cell subsets. Top right: FACS analysis of B220⁺ and CD43⁻ BM cells from WT or CD19Tln1^−/− (talin null) mice. These subsets were costained with anti-IgD and anti-IgM mAbs. Bottom panels: Absolute numbers of B220⁺ and of the indicated B subsets within equal volumes of BM suspensions from either WT or CD19Tln1^−/− mice, determined by flow cytometry. The B220⁺ and CD43⁻ subsets were also quantified by double staining of the AA4 and IgM markers. ***P < .001. n = 10. (B) Absolute numbers of total B220⁺ cells within spleen suspensions derived from either WT or CD19Tln1^−/− mice (talin null), determined by flow cytometry. ***P < .001. n = 10. (C) FACS analysis of B220⁺ spleen cells isolated from WT or CD19Tln1^−/− mice stained with anti-CD21, anti-CD24, and anti-CD23 mAbs, depicting FO, MZ, T2, and T1 B-cell subsets. (D) The fractions of spleen B220⁺ subsets determined by flow cytometry for WT versus CD19Tln1^−/− mice (talin null). *P < .05. ***P < .001. N.S. indicates not significant. n = 10. (Ei) Spleen sections of WT or CD19Tln1^−/− mice were stained with anti-B220 (green), anti-CD4 (red), and anti–MAdCAM-1 (light blue) antibodies. (Eii) Spleen sections of WT or CD19Tln1^−/− mice were stained with anti-B220 (green), anti-CD3 (red), and anti-CR1 (8C12, light blue) antibodies.