Kinetics of the local cellular response in the gastric lymph of immune and susceptible sheep to infection with Teladorsagia circumcincta.

Groups of yearling sheep were trickle infected with Teladorsagia circumcincta for 8 weeks, then the infection cleared with anthelmintic and both these animals and a group of parasite naïve sheep were challenged with 50 000 infective T. circumcincta larvae. The previously infected sheep demonstrated acquired immunity to the parasite, manifested by reduced worm burdens which were evident as early as 2 days after challenge. Cannulation of the common efferent gastric lymph duct allowed the kinetics of their local cell traffic to be monitored, and the phenotype of these lymphocytes was analysed. A blast cell response, consisting of both T and B lymphocytes, was observed in both groups of sheep, however this occurred more rapidly in the previously infected, immune animals. CD4+, CD8+ and CD25+ blast cell output peaked at day 3 in the previously infected animals, whereas CD21+ blast cell output peaked slightly later at day 5. In the control group the peak output of all phenotypes of blast cells occurred more slowly, peaking 10 days after infection.