A comparison of larval development and mucosal mast cell responses in worm-naïve goat yearlings, kids and lambs undergoing primary and secondary challenge with Teladorsagia circumcincta.

Larval development, mucosal mast cell (MMC) and eosinophil responses in worm-nai;ve lambs, yearling goats and goat kids were compared using two different experimental challenge regimes involving oral administration of infective Teladorsagia circumcincta L(3). Experimental challenge regimes enabled primary and secondary immune responses in the two species to be compared. Goats carried higher worm burdens than lambs and there were significant differences in the stages of development attained by the larval challenge that established in the two species. Possible physiological reasons for these differences are discussed. There were also differences in the establishment and development of larvae in individual yearlings which may indicate the development of a weak age-related immune response. Quantitative analysis of MMC and globule leukocyte (GL) recruitment and functional activity in the form of mast cell-specific proteinase (MCP) production demonstrated differences between the species with goat tissues containing significantly higher numbers of GL and lower concentrations of MCP than the lambs. Quantitative analysis of blood and tissue eosinophil responses failed to demonstrate any significant differences in either species under the two challenge regimes.