Figure 1. Tet1-deficiency drives B cell malignancy upon advanced age.

a) Kaplan-Meier survival curve of Tet1-deficient mice with heterozygous (Tet1^+/−, n = 44) and homozygous (Tet1^−/−, n = 78) deletion compared to wild-type mice (Tet1^+/+ n = 28). * P = <0.0005. b) Peripheral blood smears stained with Wright-Giemsa; arrows indicate normal lymphocyte (left panel) and aberrant lymphocyte (right panel). Representative of n = 8–10 mice per genotype. c) Lymph nodes from Tet1^+/+ and Tet1^−/− mice; representative of n = 8–10 mice per genotype. Scale bar = 1cm. d). Flow cytometric analysis of malignant cells in the lymph nodes of moribund Tet1^−/− compared to age-matched Tet1^+/+ mice. Upper panels; side-scatter (SSC) vs. B cells (B220⁺). Middle Panels; B220⁺ gated cells stained for progenitor/precursor B cells (IgM⁻IgD⁻), immature B cells (IgM⁺IgD⁻), transitional B cells (IgM⁺IgD^low) and mature B cells (IgM⁺IgD^high). Lower panels; B220⁺ gated cells stained for progenitor B cell marker CD43 vs. CD19 staining. Data are representative of 3 independent experiments, n = 8–10 mice per genotype. Histological analysis by H&E staining of e) liver, lung, kidney and f) lymph node sections from sick Tet1^+/− and Tet1^−/− mice compared to Tet1^+/+ controls. Arrows indicate infiltration of lymphocytes. C = cortex, M = Medulla; Scale bar = 100 μm in all panels g) Immunohistochemistry of lymph nodes from Tet1^+/+ and sick Tet1^−/− mice stained with anti-Bcl-6, anti-IRF4, anti-CD138 antibodies (brown) and hematoxylin. Scale bar = 100 μm in all panels. Data are representative of n = 4 mice per genotype.