SEQUENTIAL CELLULAR AND HUMORAL RESPONSES IN THE ABOMASAL MUCOSA AND BLOOD OF ROMNEY SHEEP DOSED WITH TRICHOSTRONGYLUS-AXEI

Pfeffer A., Douch P. G. C., Shaw R. J., Gatehouse T. K., Rabel B., Gre en R. S., Shirer C. L., Jonas W. E. & Bisset S. 1996. Sequential cellu lar and humoral responses in the abomasal mucosa and blood of Romney s heep dosed with Trichostrongylus axel. International Journal for Paras itology 26: 765-773. Abomasal cannulae were surgically placed in 7 2-y ear-old New Zealand Romney sheep which had been maintained parasite-fr ee from birth. Four of these sheep were randomly selected and dosed or ally with 10,000 infective Trichostrongylus axei larvae per week for 8 weeks, while the remaining 3 sheep served as uninfected controls. Abo masal biopsy, blood and faecal samples were obtained from all sheep at regular intervals from 5 days before and until 58 days after the firs t infection. The sheep were then killed, worm burdens assessed and abo masal and small intestinal samples collected. Faecal egg counts of all 4 dosed sheep were low and only one (No. 701) had a substantial worm burden (8400) post mortem. Overall, levels of mucosal mast cells/globu le Leukocytes, eosinophils, T19(+) cells and larval migration inhibito ry activity increased significantly in the abomasal mucosa of the dose d sheep compared to the controls. The CD4(+):CD8(+) cell ratio in the abomasal mucosa of the dosed sheep also increased compared to that of the controls (P=0.06). In blood, T. axei-specific antibody (total and IgG,) and eosinophil numbers increased significantly in the dosed shee p. Mucosal cells staining for IgE (IgE(+)), and blood and mucosal eosi nophils showed the earliest substantive increases in number followed b y increases in specific serum antibody levels, numbers of mucosal cell s fluorescing under UV light (UVf) and T19(+) cells. The difference in the IgE(+) and UVf cell responses indicated that expansion of globule leukocyte numbers lagged behind that of mucosal mast cells. The resul ts supported the concept of CD4(+) T cell help in the abomasal mucosa and defined the sequential expression of components of the immunologic al responses potentially mediating resistance to T. axel. Tn sheep No. 701, persistence of adult worms was associated with lower mucosal IgE (+) cell and eosinophil responses compared with the other dosed sheep. Copyright (C) 1996 Australian Society for Parasitology.