Fig. 4
From: Mutations in topoisomerase IIβ result in a B cell immunodeficiency
B cells are functionally impaired in the absence of Top2b, in vivo and in vitro. a Mice fail to produce specific IgG antibody in response to vaccination with ovalbumin (OVA) in the absence of Top2b in B cells (n = 9 mice per group, shown as mean ± SEM, ***p < 0.005 by the Kruskal–Wallis test). b–d Adult Top2b−/− mb1 cre and littermate mice were immunized with Pneumovax-23 (PPV23). At 6 days post-immunization (b), B cells produce PPV23-specific IgM in the absence of TOP2B, at similar levels to wild-type control mice. Four weeks after immunization with Pneumovax-23, anti-PPV23 IgG3 (c) and IgG2b (d) production is impaired in Top2b−/− mb1-cre mice compared to wild-type control animals (n = 6 WT or 5 Top2b−/− mb1 cre, shown as mean ± SEM, *p < 0.05 by the Kruskal–Wallis test). e In vitro, Top2b−/− mb1 cre mouse-derived B cells fail to proliferate, as assessed by CFSE dilution, in the presence of stimulation with LPS (blue histogram). Untreated, CFSE stained cells are shown in red. FACS plots are representative of 4 mice per group. Total number of CFSE positive cells is quantified in (f). g Top2b−/− mb1-cre mouse-derived B cells have increased cell death as measured by LDH release (n = 7 WT or 8 Top2b−/− mb1 cre mice per group, in duplicate, shown as mean ± SEM). *p < 0.05, two-tailed Student’s t test. h The B cells that do survive have reduced upregulation of the activation marker MHC II, as shown by mean fluorescence intensity (MFI). *p < 0.05, two-tailed Student’s t test (n = 4 mice per group)
