Cytokine transcript levels in yearling abomasal mucosa. Relative cytokine transcript levels in samples of abomasal mucosa, in comparison to ATPase, from naïve and previously infected yearling sheep (Scottish Blackface × Bluefaced Leicester and Dorset × Suffolk) following challenge with T. circumcincta. Previously infected sheep were orally infected with 2,000 L3 larvae three times per week for eight weeks. All sheep were treated with Levamisole (7.5 mg/kg) then challenged one week later with 50,000 L3 larvae and killed on day 0, 2, 5 or 10 following challenge. An additional group of naïve sheep were killed on day 21 following challenge. Analysed using Tukey’s test with a 95% confidence interval, n = 6 sheep per group for each time point. Significant difference between naïve and previously infected groups: *P < 0.05, **P < 0.01, ***P < 0.001. Significant difference between day 0 and corresponding day 2: #P < 0.05, ##P < 0.01.