Figure 4. CEACAM1 promotes B-cell survival in vivo.

(a) Scheme of developmental, maturation and migration stages of B cells in bone marrow, blood, lymph node and spleen. Arrows indicate most likely developmental pathway. Dotted arrow indicates still debated developmental pathway. Red arrow indicates differentiation after antigen challenge. (b–e) Representative dot blots, gating strategy and total numbers of B-cell subpopulations from wild-type (WT) and Ceacam1^−/− mice as measured by flow cytometry in bone marrow (b, n=6), in blood (c, n=4), in lymph node (d, n=4) and in spleen (e, n=10). (f,g) Representative immunofluorescence of spleen and lymph node (f, n=6) sections derived from naïve WT and Ceacam1^−/− mice after staining for B cells (B220, blue) or T cells (CD90.2, green) and spleen sections stained for marginal zone B cells (CD1d, red), follicular B cells (CD19, green), marginal zone macrophages (CD169, red) or B cells (B220, blue; g, n=6). (h) Representative immunofluorescence results of spleen sections from Jh^−/− mice that were left untreated or were subjected to adoptive transference with 1 × 10⁷ B cells derived from WT or Ceacam1^−/− mice 30 days before analysis, stained for T cells (CD90.2, green) and B cells (CD19, blue; n=3). (i,j) Representative dot blots, gating strategy and statistical analysis of B-cell subpopulations from murine bone marrow chimeras reconstituted with 1:1 composition of bone marrow from WT(CD45.1): WT(CD45.2) mice in one group and bone marrow from WT(CD45.1): Ceacam1^−/−(CD45.2) mice in another group after 45 days of reconstitution (n=5 per group) as measured by flow cytometry in blood (i) and spleen (j; only second group has been shown for FACS gating strategy). Scale bars, 300 μm. *P<0.05; **P<0.01 and ***P<0.001 (Student’s t-test); NS=not significant. Data are representative of one (h) or two (b–d,i,j) or three (e) experiments (mean±s.e.m., b–e). One representative slide of three (h) or six (f,g) slides is shown.