Antibiotic treatment response rescues preleukemic Cdkn2a^−/−Il10^−/− B cells from impaired development and DNA damage. Analysis of 8- to 12-week-old Cdkn2a^−/−Il10^+/+ and Cdkn2a^−/−Il10^−/− mice. (A) Absolute bone marrow (BM) count of total B220⁺CD19⁺ B cells and BM B-cell subsets. (B) Percent of γH2AX⁺ cells among total BM B cells and BM B-cell subsets. (C) Schematic diagram of antibiotic (ABX) treatment and tracking of peripheral blood and BM cells in adult mice. (D) Concentration of cytokines in Il10^−/−Cdkn2a^−/− mice and controls. Lines connect values from the same mouse sampled before and after antibiotic treatment. Flow analysis of the percentage of CD11b⁺CD19⁻ cells (E) and CD19⁺ B220⁺ cells (F) in BM. (G) Percentage of γH2AX⁺ of CD19⁺B220⁺ cells in Cdkn2a^−/−Il10^+/+ and Cdkn2a^−/−Il10^−/− mice after treatment with placebo (-) or antibiotics (+) for 4 weeks. Data in (A-B) are representative of 2 experiments. Data in (D-G) were obtained from a single-cohort study. Error bars represent the mean ± standard deviation. *P ≤ .05, **P ≤ .01, ***P ≤ .001, ****P ≤ .001. Statistical tests used are described in Methods.