engleski

Response of porcine intestinal lymphocytes to F4 antigen of Escherichia coli or immune response modifiers

To determine the response of porcine intestinal lymphocytes we have perorally inoculated 4-week-old pigs with either F4^+ (1466 and 2407) or F4^- (1467) nonenterotoxigenic E. coli (non-ETEC) strains and with challenge F4^+ ETEC strains (M1823 and 11-800/1/94). Also, we have evaluated in vitro and in vivo adjuvanticity of the immune response modifiers (IRMs) such as: peptidoglycan monomer (PGM), Baypamun (BPM), copolymer of polyoxyethylene-polyoxypropylene (POE-POP) and N-acetylglucosaminyl-(beta,1-4)-N-acetyl-muraminyl-L-alanyl-D-isoglutamine (GMDP) in a model of postweaning colibacillosis. Small intestinal washes were obtained immediately after euthanasia at 8, 10 and 12 days following the specific immunization, and the presence of anti-F4ac secretory IgA (sIgA) antibody was detected by use of an indirect ELISA. Simultaneously, the specimens from jejunum, ileum, and mesenteric lymph node (MLN) were taken for phenotyping the immune cells by flow cytometry and immunohistology using monoclonal antibodies reactive with swine leukocyte CD antigens, and for testing their proliferative responses. Non-ETEC strain 2407 activated lymphocytes from ileal Peyer's patches (IPP) and MLN to respond better to control mitogens (PHA and PWM; P < 0.01 or < 0.05, respectively) or IRMs (BPM and PGM, P < 0.05) than the control cells from noninoculated pigs. Non-adherent strain 1467 did not affect the in vitro responsiveness of the cells tested. About 75% of 2407+POE-POP-treated pigs, and 50% to 60% of pigs that were immunized with either 2407+GMDP or 2407 strain, respectively, had anti-F4ac sIgA antibodies. The numbers of CD4a+ and CD8a+ cells were much higher (p < 0.05) in IPP and jejunal lamina propria, respectively. In 2407+GMDP- or 2407-treated pigs we have observed that T cell antigen - CD3a - was expressed on jejunal/ileal intraepithelial lymphocytes and numerous cells in the extrafollicular areas of MLN and dome region of IPP. The B cells expressing CD21 surface molecule were demonstrable in the interfollicular areas of MLN and the germinal centers of IPP in 2407-treated pigs. A strong reaction to sIgA was exhibited by plasma cells in the lumen of the crypts and by those residing the lamina propria of jejunum/ileum. It was concluded that peroral immunization of weaned pigs with F4ac^+ non-ETEC strain may induce a local (intestinal) immune response, which can be additionally enhanced by IRMs tested.

Intestine; lymphocyte; Escherichia coli; immune response modifiers; pigs

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