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Cytokine and antibody subclass responses in the intestinal lymph of sheep during repeated experimental infections with the nematode parasite Trichostrongylus colubriformis
- Pernthaner, A., Cole, S.A., Morrison, L., Green, R., Shaw, R.J., Hein, W.R.
- Veterinary immunology and immunopathology 2006 v.114 no.1-2 pp. 135-148
- lymph, messenger RNA, genetic resistance, Trichostrongylus colubriformis, interleukins, food animals, sheep, nematode infections, tumor necrosis factor-alpha, animal parasitic nematodes, intestines, immunoglobulins, genotype, gene expression, immune response, pest resistance, interferons
- The expression of interleukin (IL)-4, IL-5, IL-10, IL-13, TNF-α and IFN-γ genes, and parasite-specific IgM, IgG1, IgG2, IgA and total IgE levels, were monitored daily in intestinal lymph of sheep infected repeatedly with the nematode parasite Trichostrongylus colubriformis. Host genotype had a significant influence on IL-13 gene activity, with resistant-line (R) sheep consistently expressing higher levels of mRNA than susceptible-line (S) sheep. Mean gene expression of IL-13, IL-4 and IFN-γ did not differ significantly between the first and second nematode challenge. Field-primed R and S as well as field-primed R and naïve S sheep had lower mean gene expression of IL-5 and IL-10, respectively, during the second when compared to primary challenge. Genes for IL-13 and IL-5 were transiently and strongly up-regulated after nematode infection, particularly in animals with previous exposure to nematodes. Genes for TNF-α and IFN-γ were also transiently up-regulated, but to a lesser extent and more typically after primary challenge. Naïve sheep of both genotypes produced relatively little antibody response after primary challenge. A second nematode challenge resulted in large increases in the lymphatic levels of all antibody sub-classes which were significant for adult antigen-specific IgA and larval antigen-specific IgG1. In naïve S line sheep, the larval-specific IgA and IgG2 response appeared delayed when compared to the R line animals. Field-primed R and S line sheep had relatively high lymphatic IgG1 levels prior to experimental infection and these did not change significantly afterwards. These results demonstrate that during nematode infections, the intestinal micro-environment of sheep is transiently skewed towards Th2 cytokine dominance, although IFN-γ gene expression continues. This response is accompanied by increases of nematode-specific IgG1, IgA, IgG2 and IgM, as well as of total IgE in lymph plasma.