Intestinal immune response of Silurus glanis and Barbus barbus naturally infected with Pomphorhynchus laevis (Acanthocephala).

Immunopathological and ultrastructural studies were conducted on the intestine of barbel Barbus barbus and sheatfish Silurus glanis that were naturally infected with the acanthocephalan Pomphorhynchus laevis. Enteric helminths often cause inflammation of the digestive tract, inducing the recruitment of different types of immune cells at the site of infection. The results of our study clearly demonstrated that mast cells (MC) were the dominant immune cells which occur at the site of inflammation in both hosts. MC were associated with fibroblasts and were found in close proximity to, and inside, the capillaries of the intestine, thus, migration of mast cells via the bloodstream was suggested. Significant degranulation of MC was present. Immunohistochemical staining revealed met-enkephalin and serotonin (5-HT) in intestinal MC of both uninfected and infected barbel and the absence of the antimicrobial peptides piscidin 3 and piscidin 4 in both species. Data are discussed with respect to host immune response to an intestinal helminth and compared with other host-parasite systems.