engleski

Effect of levamisole on the goblet cells in the small intestine of pigs immunized with F4ac+ or F18ac+ non-enterotoxigenic Escherichia coli strains

Postweaning colibacillosis is etiologically complex disease commonly induced by F4ac^+ or F18ac^+ porcine enterotoxigenic (ETEC) strains. A complete immune protection is not achieved either by live or subunit (fimbrial) vaccines for parenteral use or by attenuated vaccines for peroral use comprising thermally treated ETEC strains. The intestinal goblet cells are interspersed among the absorptive cells of the mucosal epithelium. Their function is synthesis of the water-soluble mucins. When released from the goblet cells, mucin protects the underlying mucosa from various insults, such as those induced by microbial or dietary antigens, toxins and digestive enzymes. The objective of this study was to determine nonspecific immunomodulatory effect of levamisol in the combination with specific intragastric immunization of weaned pigs with either F4ac^+ or F18ac^+ vaccine candidate non-ETEC strains on the population of the ileal goblet cells. Twelve 4-week old (just weaned) pigs were assigned to 5 groups and immunized with F4ac^+ or F18ac^+ non-ETEC strains, or with or without levamisol. All pigs were euthanatized and samples of ileum (1 cm) were collected, fixed in methacarn, dehydrated, embedded in paraplast and 7 ľm sections were stained with Alcian blue (AB, pH 2.5) which stains acidic carbohydrates and periodic acid-Schiff (PAS) for demonstration of neutral carbohydrates. The volume density (V_V) of the AB^+ and PAS^+ goblet cells was determined using stereological point-counting method. The most numerous were AB^+ goblet cells in pigs immunized with F4ac^+ non-ETEC strain (V_V = 0.262 ą 0.018 mm^0). The Vv of AB^+goblet cells in levamisol treated pigs was 0.159 ą 0.023 mm^0, but the difference was not significant. Hence, levamisol used as an immune response modifier/adjuvant in this model did not induce hyperplasia of the goblet cells, and thus, did not alter a normal function of mucosal surface in the ileum of weaned pigs.

Intestinal goblet cells; immunization; E. coli; levamisole; pigs

nije evidentirano