T cell activation in vivo causes IFN-γ dependent Paneth loss. (A–G) Wild-type and IFN-γ KO mice were injected i.p. with anti-CD3 antibody (50 µg/mouse); as a control PBS was injected in wild-type mice. 24 h after injection, mice were sacrificed for histological analysis. Groups of n = 7 animals per condition were used and results were reproduced in 2 independent experiments. (A) Lysozyme immunostaining shows reduced PC granules after T cell activation in wild-type but not in IFN-γ KO mice. (B) Quantification of lysozyme-positive cells per crypt section in 45 crypts/animal/region. Mean number ± SD is shown. *, P < 0.05; **, P < 0.01; ***, P < 10−4; Student’s t test compared with control-injected mice. (C) Defa6 in situ hybridization. (D) Quantification of Defa6+ cells per crypt section; mean cell number ± SD is shown. **, P < 10−3; ***, P < 10−5; Student’s t test compared with control-injected mice. (E) Cleaved Caspase-3 immunostaining shows pronounced induction of apoptosis in both wild-type and IFN-γ KO crypts. (F) Quantification of cleaved Caspase-3+ cells per crypt section. Mean cell number ± SD is shown. ***, P < 10−6; Student’s t test compared with control-injected mice. (G) Co-staining of cleaved Caspase-3 (red) and PC granules (UAE-1; green) shows broad induction of apoptosis, also in non-PCs. Nuclei stained with DAPI (gray). Bars, 50 µm.
