Mature Tln1^−/− B cells cannot enter lymph nodes or home to BM. (A) Top: FACS analysis B220⁺ inguinal lymph node (LN) cells from WT or CD19 Tln1^−/− mice stained with anti-IgD and anti-IgM mAbs. Bottom: Absolute numbers of total (B220⁺) and mature (IgD⁺) cells isolated from either inguinal (left) or cervical lymph nodes (right) of WT or CD19 Tln1^−/− mice (talin null). ***P < .001 for the compared groups. n = 10. (B) Left images: Inguinal LN sections stained with anti-B220 (green), anti-CD3 (red), and anti-CR1 (8C12, light blue). Right images: Similar LN sections stained with anti-IgD (green) and anti-CD3 (red). (C) Competitive adoptive transfer of WT versus talin1-deficient B cells into WT recipient mice. The numbers of B220⁺ B cells from either WT or CD19Tln1^−/− spleens, each labeled with a different fluorescent cell tracker (CMTMR or CFSE), recovered in both the inguinal and cervical lymph nodes of recipient mice 20 hours after intravenous. injection. The numbers of differentially dye labeled T cells recovered in these organs were determined by anti-CD3 staining and are shown for comparison. ***P < .001. n = 6. N.S. indicates no statistical significance. (D) The numbers of competitively transferred B220⁺ B cells or CD3⁺ T cells from either WT or CD19Tln1^−/− spleens (CD19 talin null), labeled as in panel C and recovered in the BM of recipient WT mice, were determined after 20 hours by flow cytometry. The numbers of dye-labeled T cells recovered in these organs were determined by anti-CD3 staining and are shown for comparison. ***P < .001. n = 6. (E) Competitive adoptive transfer of WT versus talin1-deficient B cells into WT recipient mice. Dye-labeled splenocytes (15-25 × 10⁶) from WT or CD19Tln1^−/− spleens were coinjected into WT host mice. Dye-labeled B cells were determined in the spleen of the recipient mice after 20 hours by B220 staining. ***P < .001. n = 6. (F) Steady-state numbers of circulating WT and talin1-deficient B cells and WT T cells. Absolute cell numbers of either B220⁺ or CD3⁺ peripheral blood lymphocytes determined in equal blood volumes of either WT or CD19Tln1^−/− mice (CD19 talin null). ***P < .001. n = 4.