Studies on the role of mucus and mucosalhypersensitivity reactions during rejection ofTrichostrongylus colubriformis from the intestine ofimmune sheep using an experimental challenge model

Markers/parameters for the evaluation of natural resistance status of small ruminants against gastrointestinal nematodes

“…It has been confirmed that both mast cells and intraepithelial mucosal mast cells (globule leucocytes) are present in substantial numbers in abomasal tissue niches of hypersensitized and relatively resistant animals. Additionally, mucosal tissue eosinophilia, increased mucus production and the Evaluation of resistance status of small ruminants presence of inhibitory substances in the mucus have been consistently observed in relation to the development of immunity to GINs in ruminants (Huntley et al, 1984 andPfeffer et al, 1996;Harrison et al, 1999;Balic et al, 2000b;Bricarello et al, 2004). Differences in cellular counts in resistant and susceptible individuals/breeds and their possible role as parameters are summarized in the following.…”

“…The level of immunoglobulins may also be helpful in determining the resistance and/or the tolerance potential of the host against GINs as infection involves the production of parasitespecific immunoglobulins such as IgA, IgG1 and IgE (Pfeffer et al, 1996;Harrison et al, 1999 andGill et al, 2000;Huntley et al, 2001;Strain and Stear, 2001) and these are powerful aids to verify the results of other practiced phenotypic parameters. Stear et al (1995) reported a strong correlation between immunoglobulins and worm burden in a study carried out on Rhö n sheep.…”

“…circumcincta, and a positive correlation between mast cells and worm fecundity has also been reported. Although globule leucocytes seem to posses stronger association with host resistance, yet increase in mucosal mast cells has been observed in many situations corresponding to changes in the host resistance with respect to age, physiological state and vaccination; thus, failing in understanding their precise role in this mechanism (Harrison et al, 1999). Mucosal mast cells appeared to be involved in expulsion of worms within 2 to 4 h of a challenge infection via an intense IgE-mediated hypersensitivity reaction (Miller, 1984).…”

Relationship of intestinal histology with the resistance to Trichostrongylus colubriformis infection in three breeds of sheep

“…The elucidation of the mechanism that controls such genetic variations in resistance to nematode parasites is critical to design an effective parasite vaccine, and to develop methods to identify geneticallyresistant breeding livestock (Gill et al 2000). Harrison et al (1999) showed that sheep that are immune to Trichostrongylus colubriformis had higher antibody and histamine levels as well as greater numbers of mucosal mast cells and globule leucocytes after challenge, compared to naive sheep. These results are evidence for an immediate hypersensitivity reaction in the intestine of immune sheep, from where challenge larvae may be expelled within 2 h (Harrison et al 1999 Trichostrongylus colubriformis and then allowed to graze on infected pasture had significantly more globule leucocytes, mast cells and eosinophils in gastrointestinal tissue and significantly higher levels of mucous antiparasitic activity than unimmunized sheep (Douch 1989).…”

“…Harrison et al (1999) showed that sheep that are immune to Trichostrongylus colubriformis had higher antibody and histamine levels as well as greater numbers of mucosal mast cells and globule leucocytes after challenge, compared to naive sheep. These results are evidence for an immediate hypersensitivity reaction in the intestine of immune sheep, from where challenge larvae may be expelled within 2 h (Harrison et al 1999 Trichostrongylus colubriformis and then allowed to graze on infected pasture had significantly more globule leucocytes, mast cells and eosinophils in gastrointestinal tissue and significantly higher levels of mucous antiparasitic activity than unimmunized sheep (Douch 1989). Winter et al (1997) reported an increase in mucosal eosinophil and mast cell numbers in Suffolk lambs during the period of the rejection of adult Nematodirus battus, as compared to uninfected control animals.…”