Stool levels of TNF and TNF-RII during induction of chronic DSS colitis. Levels of TNF (panel A) and TNF-RII (panel B) were determined by enzyme immunoassay in stool samples obtained before DSS exposure began, at the end of each 5 day cycle of DSS administration, and after 16 days of recovery prior to beginning the next DSS cycle for wild type (n = 49–50 mice for days 0, 47, and 62, and n = 9 – 10 for the remaining time points) and RAG-2-/- mice (n = 14). Mean cytokine concentrations per 100 mg stool are shown. Error bars are omitted for clarity. * indicates values significantly different from pre-treatment level for a given genotype. # indicates values significantly different (p ≤ 0.02) in wild type vs. RAG-2-/- mice.