Two stable rough mutants of Salmonella spp. were studied as live peroral vaccines. The SF1591 mutant of S. typhimurium (Ra chemotype) protected germ-free piglets against subsequent infection with virulent smooth S. typhimurium LT2, whereas a deep-rough mutant of S. minnesota mR595 (Re chemotype) did not. We investigated cytokine and leukocyte profiles in the ilea of gnotobiotic piglets colonized for 1 week either with rough mutants alone or with rough mutants followed by S. typhimurium LT2. The ileal mucosae of piglets associated with strain SF1591 alone were not inflamed. Villi contained activated macrophages, and enterocytes expressed transforming growth factor beta (TGF-beta). Subsequent infection of piglets with S. typhimurium LT2 resulted in immigration of alphabeta T cells and immunoglobulin A (IgA) response. In contrast, the ileal mucosae of piglets associated with strain mR595 alone expressed heat shock proteins and inflammatory cytokines but not TGF-beta. Acellular villi contained numerous gammadelta T cells but no alphabeta T cells. After subsequent challenge with the LT2 strain, most piglets died of sepsis. Intestinal mucosae contained IgG but no IgA. These findings suggest the importance of cytokine signals in the regulation of intestinal responses against Salmonella infection.

• MeSH
• Cytokines immunology   MeSH
• Germ-Free Life * MeSH
• Ileum immunology   microbiology   pathology   MeSH
• Swine, Miniature MeSH
• Swine MeSH
• Salmonella typhimurium * MeSH
• Salmonella Infections, Animal immunology   pathology   MeSH
• Animals MeSH
• Check Tag
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Cytokines MeSH

The aim of this study was to investigate spontaneous immunoglobulin production and a pattern of isotype switching by thymic B lymphocytes (TBL) as compared with cells isolated from spleen during early ontogeny using a pig model in which B-cell development is not influenced by maternal regulatory factors. A sensitive ELISPOT assay was therefore employed to detect immunoglobulins in pig fetuses, colostrum-deprived germ-free (GF) piglets as well as conventionally (CONV) reared pigs. The first spontaneously immunoglobulin-secreting cells in the thymus were detected in 67-day-old fetuses (the length of gestation period in pigs is 114 days), their number increasing during fetal ontogeny. In contrast to fetal splenic cells, which secrete exclusively IgM, fetal thymic immunoglobulin-secreting cells were determined to undergo spontaneous isotype switching to IgG and IgA. In 28-day-old GF piglets and 3-month-old CONV pigs the number of thymic immunoglobulin-secreting cells of all isotypes was comparable to the number of thymic immunoglobulin-secreting cells detected in the newborn thymus. Considerable augmentation of IgG and IgA production by splenic immunoglobulin-secreting cells in CONV pigs was observed as compared to GF newborns and GF piglets, in which IgG- and IgA-secreting cells were detected occasionally. Our results indicate that TBL represent the first B-cell population in early fetal ontogeny spontaneously undergoing isotype switching to IgG and IgA; in the postnatal period the TBL population does not appear to be influenced by external antigenic stimuli of conventional microflora.

• MeSH
• B-Lymphocytes immunology   MeSH
• Enzyme-Linked Immunosorbent Assay MeSH
• Gestational Age MeSH
• Germ-Free Life * MeSH
• Immunoglobulin A biosynthesis   MeSH
• Immunoglobulin G biosynthesis   MeSH
• Immunoglobulin M biosynthesis   MeSH
• Immunoglobulin Isotypes biosynthesis   MeSH
• Swine, Miniature embryology   growth & development   immunology   MeSH
• Swine MeSH
• Immunoglobulin Class Switching MeSH
• Spleen growth & development   immunology   MeSH
• Thymus Gland embryology   growth & development   immunology   MeSH
• Animals MeSH
• Check Tag
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Comparative Study MeSH
• Names of Substances
• Immunoglobulin A MeSH
• Immunoglobulin G MeSH
• Immunoglobulin M MeSH
• Immunoglobulin Isotypes MeSH

Immunoglobulin (Ig) response to different polyclonal B-cell activators was measured by ELISA in cell culture media of thymocytes, splenocytes and liver cells isolated from pig fetuses, 8-d-old germ-free piglets and conventionally reared pigs. Both in fetal and in postnatal life polyclonally stimulated lymphocytes were found to produce predominantly the IgM isotype; the first IgM formation was detected in 50-d-old fetal liver (gestation in pigs lasts 114 d). Surprisingly, 73-d-old fetal thymic cells were shown to be induced to Ig synthesis and secretion. In contrast to splenocytes of the same age, which secreted exclusively IgM, fetal thymocytes produced IgM, IgG and IgA. Polyclonally stimulated splenic cells as compared with thymic cells started to produce IgA later in fetal ontogeny, whereas the IgG response was not detectable in splenic cell culture media during the whole embryonal development and appeared only after birth. The earliest and the highest Ig stimulation was found after cultivation of lymphocytes with Nocardia delipidated cell mitogen. Interestingly, the moderate stimulatory effect of 65-kDa heat shock protein (Hsp-65) in polyclonal IgM response of fetal splenocytes was observed. We showed that thymic B lymphocytes represent probably the first maturing B cell population detectable in fetal life, which is able to differentiate after polyclonal stimulation into IgM as well as IgA and IgG producing cells.

• MeSH
• Lymphocyte Activation * MeSH
• B-Lymphocytes drug effects   immunology   MeSH
• Bacterial Proteins * MeSH
• Chaperonin 60 MeSH
• Chaperonins immunology   MeSH
• Enzyme-Linked Immunosorbent Assay MeSH
• Germ-Free Life immunology   MeSH
• Liver cytology   embryology   growth & development   immunology   MeSH
• Lipopolysaccharides immunology   MeSH
• Pokeweed Mitogens immunology   MeSH
• Mitogens immunology   MeSH
• Organic Chemicals MeSH
• Organ Culture Techniques MeSH
• Fetus immunology   MeSH
• Swine embryology   growth & development   immunology   MeSH
• Spleen cytology   immunology   MeSH
• Thymus Gland cytology   embryology   growth & development   immunology   MeSH
• Antibody Formation * MeSH
• Animals MeSH
• Check Tag
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Bacterial Proteins * MeSH
• Chaperonin 60 MeSH
• Chaperonins MeSH
• heat-shock protein 65, Mycobacterium MeSH Browser
• Lipopolysaccharides MeSH
• Pokeweed Mitogens MeSH
• Mitogens MeSH
• Nocardia delipidated cell mitogen MeSH Browser
• Organic Chemicals MeSH

A monoclonal antibody (ML30) recognizing the 65-kDa heat-shock protein of mycobacteria and reacting with homologous human protein was found to stain various porcine tissues. Development of this reactivity was studied. The first ML30-positive cells were embryonic hepatocytes. The protein reacting with the ML30 antibody was localized predominantly in the Golgi area and mitochondria of hepatocytes. Cell membranes of some peripheral blood lymphocytes were also found to bind ML30.

• MeSH
• Embryo, Mammalian metabolism   MeSH
• Immunoenzyme Techniques MeSH
• Liver embryology   metabolism   MeSH
• Humans MeSH
• Antibodies, Monoclonal MeSH
• Animals, Newborn MeSH
• Swine MeSH
• Heat-Shock Proteins biosynthesis   MeSH
• Animals MeSH
• Check Tag
• Humans MeSH
• Female MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Antibodies, Monoclonal MeSH
• Heat-Shock Proteins MeSH