Up-regulation of TNF-α and iNOS mRNA precedes the symptoms of inflammatory disease and can be detected as early as day 3. The mRNA levels for TNF-α, iNOS, and IFN-γ in the thymus, liver, and salivary gland at (A) 3 days and (B) 2 weeks after birth. Bars represent the mean values ± SE from 4 to 5 mice, with tc-ptp^-/- values (▪) shown as fold increase from those of age-matched tc-ptp^+/+ mice (□). Statistical significance was determined by a 2-tailed unpaired Student t test. ^*P < .05; ^**P < .005 tc-ptp^-/- compared with tc-ptp^+/+. ND indicates not determined.