Fig. 2.

Microbial colonization during early life prevents the CD1d/iNKT cell-dependent high mortality in oxazolone colitis in GF mice. (A to C) Eight-week-old GF and SPF mice were treated once with 1 mg of 19G11 or isotype control IgG2b antibody before presensitization and rectal oxazolone challenge. (A) Survival after oxazalone challenge is shown. (B) On day 5, the colons were collected for histological analysis, and (C) the cytokine concentration in the supernatant of 24 hours-colon organ explant cultures was measured with ELISA (n ≥ 4 mice per group). (D) Colonic LP lymphocytes were analyzed for iNKT cells by flow cytometry. (GF/a) mice were GF mice that were exposed to SPF environmental conditions at the age of 5 weeks and maintained for 4 more weeks. (GF/n) mice were pups exposed to SPF conditions on their first day of life and maintained under SPF environmental conditions for 8 to 9 weeks. Each circle represents a mouse. (E to F) Colonized mice were treated as above with oxazolone (n = 5 mice per group). All data were obtained from more than two independent experiments with similar results. Error bars indicate SD. *P < 0.05, **P < 0.01, unpaired t test and *P < 0.05, log-rank test in (A) and (E).