Fig. 5
From: Mutations in topoisomerase IIβ result in a B cell immunodeficiency
B cell development is negatively affected whenTOP2B is mutated. a Spleen to body weight ratio for wild-type (n = 3), Top2b−/−-mb1 cre (n = 3), and Top2b+/EE587E mice (n = 4) reveal smaller ratios in knockin and knockout mice compared to controls (shown as mean ± SEM). *p < 0.05 by Kruskal–Wallis test. b Total serum IgG is reduced in Top2b−/− mb1 cre mice (n = 6) and Top2b+/EE587E (n = 4) mice compared to controls (n = 7, shown as mean ± SEM). *p < 0.05 by Kruskal–Wallis test. c, d Heterozygous mutant mice fail to produce specific IgG antibody in response to vaccination with ovalbumin (OVA, n = 4, (c) or pneumovax-23 (d) (n = 3 mice per group, shown as mean ± SEM, *p < 0.05 by the Kruskal–Wallis test). Bone marrow (e) and spleen (f) cells were isolated from Top2b+/EE587E mice and littermate controls. Phenotypic analysis by flow cytometry demonstrates that the bone marrow of Top2b+/EE587E mice (n = 3) have fewer PrePro B cells (Fr. A, B220+, CD43−, BP1−, CD24−), Pre B cells (Fr. D, B220+, CD43−, IgD−, IgM−), and immature B cells (Fr. E, CD19+, B220+, CD43−, IgM+, IgD−) compared to control mice (e). In the spleen (f), there are overall fewer B cells with significant reductions in transitional (CD19+, B220+, IgDlo, IgM+, CD21/35int, CD23 variable), follicular (CD19+, B220+, IgMlo, IgDhi, CD38+) and activated (CD19+, B220+, IgDhi, IgMhi, Flt3+) B cells compared to control mice (n = 4, shown as mean ± SEM, absolute numbers calculated from whole tissue numbers). *p < 0.05; **p < 0.01, two-tailed Student’s t test. Expression of mutant Top2b results does not affect E2A (g, n = 6)) or Rag1 (h, n = 8) expression in common lymphoid progenitor cells (compared to WT n = 6), whereas B cell-specific transcription factors Pax5 (i) and Foxo1 (j) show reduced expression of compared to wild-type mice. (n = 4 mice per group, shown as mean ± SEM, *p < 0.05, two-tailed Student’s t test)
