Immunopathogenesis of Ascaridia galli infection in layer chicken.

Gastro-intestinal nematode infections in mammals are associated with local T lymphocyte infiltrations, Th2 cytokine induction, and alterations in epithelial cell secretion and absorption. This study demonstrates that Ascaridia (A.) galli infection in chicken also elicits local gut-associated immune reactions and changes in the intestinal electrogenic nutrient transport. In A. galli-infected birds we observed infiltrations of different T cell populations in the intestinal lamina propria and accumulation of CD4+ lymphocytes in the epithelium. The Th2 cytokines IL-4 and IL-13 dominated the intestinal immune reactions following A. galli infection. A. galli-specific systemic IgY antibodies were detected after two weeks post infection, and did only poorly correlate with detected worm numbers. Electrogenic transport of alanin and glucose was impaired in A. galli-infected chicken. Our data provide circumstantial evidence that local immune responses and electro-physiological intestinal functions may be connected and contribute to the elimination of worm infection.