(A) Histological analysis by H&E staining of large intestine of control, ATM-/-, ATMINΔL, NBS1ΔL, ATMINΔLNBS1ΔL mice at 12 weeks of age. (B) Histological scores of the large intestine of control, ATM-/-, ATMINΔL, NBS1ΔL, ATMINΔLNBS1ΔL and 3 individual moribund ATMINΔLNBS1ΔL mice. (C) Histological analysis by anti-CD3 staining of the large intestine of control and a moribund ATMINΔLNBS1ΔL mouse. (D) Representative flow cytometry data of CD4 and CD8 expression, as well as (E) TCRβ and TCRγδ expression on isolated IELs from the small intestine of control, ATMINΔL, NBS1ΔL and ATMINΔLNBS1ΔL mice, along with the quantification of D-E. N = 5–8 mice per genotype. (F) Representative flow cytometry data of IL17A and IFNγ production by YFP- and YFP+ IELs (gated on the CD4+ population) isolated from the small intestine of control and ATMINΔLNBS1ΔL mice after PMA and ionomycin stimulation. (G) Large intestinal sections from control, ATM-/-, ATMINΔL, NBS1ΔL and ATMINΔLNBS1ΔL mice were stained for γH2AX and DAPI. Error bars represent SEM (**P<0.01, ***P<0.001).