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Biomedical subjects

E Telemo

Publications and source records attributed to E Telemo.

At least 37 records · Page 2Linked to original sources
PubMed1996

Antibodies in milk.

The immaturity of the infant's immune system and the rapid evolution of pathogens has created a demand for the mother to provide ready made specific defence factors to her offspring. This is achieved during the fetal period by transplacental transport of IgG antibodies, and after birth via IgA antibodies in the breast milk. The breast milk also contains a variety of nonspecific defence factors contributing to its antimicrobial effect. Breast feeding has been shown to decrease morbidity in gastroenteritis, septicemia, otitis media, urinary tract infection, encephalitis, pneumonia, and necrotizing enterocolitis. The antibody content in the mother's milk probably contributes not only to the immediate but also to the long term protection of the infant including both resistance to infection and development of immunological tolerance to harmless environmental antigens.

Antibodies↗
PubMed1996

Different expression of IL-2 receptor alpha-chain on a lamina propria T cell population and goblet cells in rats orally tolerized or sensitized to ovalbumin (OA) after colonization with an OA-producing Escherichia coli.

The aim of this study was to compare the local gut immune response in sensitized and orally tolerized experimental animals. The development of IgE/IgG antibodies and the DTH to OA was studied in rats made orally tolerant to OA and compared with sensitized control rats after colonization with an Escherichia coli genetically engineered to produce OA. At 3 weeks of age, pups were weaned onto a standard diet without OA or an OA-containing diet for 4 weeks and then switched to a standard diet without OA. Both groups of rats were parenterally immunized with a mixture of OA and human serum albumin (HSA) in Freund's complete adjuvant when they were 8 weeks old. After DTH measurement 2 weeks later, all rats were colonized with an E. coli producing OA for 5 days. The local immune response in the small intestine was assessed, using immunohistochemistry, as the expression of MHC class II molecules and IL-2 receptor (IL-2R) alpha-chain. The OA-tolerant rats showed the classical signs of oral tolerance, with a reduced IgE and IgG antibody and DTH response to OA before colonization. The difference between the two groups in the anti-OA antibody response became even more pronounced after colonization with the E. coli that produce OA. Rats orally tolerant to OA maintained a normal villus architecture after colonization, with a normal expression of MHC class II molecules similar to non-treated adult rats, but with a significantly higher (P = 0.004) expression of IL-2R alpha-chain on T cells in the lamina propria of the villus core compared with sensitized control rats. The tolerant rats showed a very weak staining with the anti-IL-2R alpha-chain-specific antibody on a few goblet cells in only one out of seven rats. In the sensitized control rats, a marked local immune response was seen with an intense staining with a monoclonal anti-IL-2R alpha-chain-specific antibody on goblet cells in five out of seven rats (P = 0.019) and also an increased expression of MHC class II molecules in the epithelial cells and cells in the lamina propria of all rats. Rats orally tolerant to OA maintained a normal villus architecture after colonization, but with a significantly higher (P = 0.004) expression of IL-2R alpha-chain on T cells in the lamina propria of the villus core compared with sensitized control rats. The novel finding that goblet cells express IL-2R alpha-chain and the striking difference in expression of the receptor and the numbers of goblet cells between tolerant and sensitized rats may suggest a direct T cell regulation of the goblet cells. A possibility that oral tolerance might be maintained by the activated T cells expressing IL-2R alpha-chain in the lamina propria of the villus core is also discussed.

Administration, Oral↗
PubMed1996

Oral tolerization leads to active suppression and bystander tolerance in adult rats while anergy dominates in young rats.

Oral tolerance was induced in 4-week-old (young) and 12-week-old (adult) rats by feeding ovalbumin (OvA)-containing pellets during 4 weeks. Seven weeks after removal of the OvA-pellets the rats were immunized with a mixture of OvA and human serum albumin (HSA) in Freund's complete adjuvant (FCA), and the following immune response was monitored. Both the young and adult groups of OvA-fed rats had significantly suppressed OvA-specific delayed-type hypersensitivity (DTH) responses and T-cell proliferation, reflecting a long-lasting T-cell tolerance to OvA both in vivo and in vitro. Furthermore, spleen cells from rats tolerized as adults were able to suppress the proliferation of primed T-cells from normal immunized rats, demonstrating the presence of antigen-specific suppressive cells. Accordingly, the adult rats showed bystander suppression of the response to HSA with respect to DTH-reaction, specific proliferation, and reduced enlargement of the draining lymph nodes after immunization. There was no evidence of active suppression in vitro or bystander tolerance in the orally tolerized young group, indicating that anergy rather than active suppression was prevalent in these rats. Furthermore, in the young group there was no suppression of the antibody response since the IgG and IgE anti-OvA antibody levels were indistinguishable from those of the controls. Contrary to the young rats, the adult fed group showed transiently elevated levels of IgG anti-OvA antibodies at 1 week post-immunization, followed by a subsequent significantly suppressed IgG antibody response. In conclusion, the results demonstrate that the induction of anergy or active suppression after antigen feeding can be determined by the age at which the antigen is introduced to the mucosal immune system.

Administration, Oral↗
PubMed1995

Effect of early weaning on the development of immune cells in the pig small intestine.

The controlled effects of age and weaning on the numbers of CD2+ T cells, subsets (CD4+, CD8+), accessory cells (macrophage/granulocyte) and cells expressing MHC class II (DQw) and IL-2R in the piglet intestine was investigated. At birth low numbers of CD2+CD4-CD8- cells were the only demonstrable T cells in the intestine. Monocyte/granulocyte and MHC class II+ cells were also detected in low numbers and IL-2R+ cells were proportionally quite numerous. All those cell populations, except the IL-2R+ cells, increased thereafter and peaked at Week 7 when the numbers of cells were comparable with those of adult animals. CD4+ cells increased dramatically after Week 1. In contrast, CD8+ remained scarce until after 5-7 weeks of age in unweaned animals. Four days after weaning at 3 weeks old, there were increases in CD2+ (P < 0.001) and macrophage/granulocyte (P < 0.01) cells in proximal small intestinal villi and in CD2+ cells only (P < 0.01) in crypts. No significant changes in cell numbers were demonstrated in the distal small intestine.

Aging↗
PubMed1995

Bystander suppression of the immune response to human serum albumin in rats fed ovalbumin.

Bystander suppression of delayed-type hypersensitivity (DTH) and the antibody response to human serum albumin (HSA) were studied in young normal rats and in young rats made partially tolerant to ovalbumin (OVA) by feeding an OVA-containing diet for 4 weeks from weaning. At 2 months of age, the animals were intracutaneously immunized with a mixture of OVA and HSA in Freund's complete adjuvant (FCA) at one site of the back, or separately at two different sites on the back. All rats made orally tolerant to OVA showed a significantly reduced IgE and IgG anti-OVA antibody production and DTH response to OVA, compared to the controls. OVA-fed rats subsequently immunized with a mixture of OVA + HSA had significantly lower IgE and DTH responses to HSA than the controls. When rats were immunized with OVA and HSA at two different sites, however, there was no difference in the response to HSA between the OVA-fed rats and the control rats, which rules out the possibility of shared epitopes between the antigens. Ear-challenge with the mixture of OVA + HSA gave a significantly lower DTH reaction in the tolerant rats immunized with a mixture of the antigens, compared to the control rats. However, suppression of the DTH reaction was not seen when tolerant and control rats were immunized with HSA alone and challenged with the mixture of OVA + HSA in one ear. These results present evidence that young rats orally tolerant to one antigen show a suppressed T-cell and antibody response to an unrelated antigen, provided that the two antigens are given in a mixture during the inductive phase. There was no evidence for bystander suppression of the T-cell response at the effector site.

Animals↗
PubMed1994

The effect of delayed weaning on the development of oral tolerance to soya-bean protein in pigs.

The antibody response to a dietary antigen (soya-bean protein) and the development of oral tolerance was studied in pigs in a family pen system where the piglets are left with their mothers and gradually wean themselves onto a soya-bean-based diet over a 12 week period. In the first experiment three groups of pigs (eight pigs/group) aged either 2, 8 or 13 weeks were immunized with soya-bean protein or ovalbumin (OvA; controls) intra-peritoneally (i.p.) in Quill A adjuvant and subsequently boosted 2 weeks later. All groups showed an IgG response to the injected antigens indicating lack of tolerance induction to the dietary antigen. Interestingly the groups injected with OvA showed an almost identical response to soya-bean protein as the groups injected with soya-bean protein. In a second experiment with a similar protocol, soya bean was withdrawn from the feed before immunization which resulted in lack of response to soya-bean protein in the groups injected with OvA and a lack of response to injected soya-bean protein in the 14-week-old group, indicating that systemic tolerance was established by 12 weeks of age. The results from the two experiments suggest a compartmentalized response to soya-bean protein i.e. local antibody production to dietary soya bean along with systemic tolerance to injected soya-bean protein. The work also suggests that delayed 'natural' weaning may avoid damaging hypersensitivity reactions associated with early weaning.

Aging↗
PubMed1994

Altered immune response to proteins fed after neonatal exposure of piglets to the antigen.

The weaning of piglets onto soya proteins at 3 weeks old normally results in an active response to the fed protein, as determined by the appearance of serum IgG antisoya antibody. This system thus allows the effects of manipulation on the response to a fed protein to be studied. In animals previously given 1 g of soya protein at birth, the magnitude of the antibody response to soya fed at 3 weeks was decreased, although similar amounts of the fed protein could be detected in serum. In addition, the relative affinity of the dominant interaction between antigen and antibody was reduced in these piglets by almost an order of magnitude. By comparison, the ability of piglets given soya at birth to respond to injected soya was not significantly reduced. These results indicate that the regulation of responses to fed and systemic antigens is largely separate. Very early oral exposure to antigen may affect the ability of neonatal animals to mount immune responses to, specifically, fed proteins while leaving the response to systemic antigen largely intact.

Animals↗
PubMed1994

Immune response against ovalbumin in rats colonized with an ovalbumin-producing Escherichia coli and the influence of feeding ovalbumin.

The influence of feeding ovalbumin (OA) on the development of IgE/IgG antibodies and delayed-type hypersensitivity (DTH) against OA was studied in rats colonized from birth with an Escherichia coli genetically manipulated to produce OA. At 21 days of age, colonized pups and pups with a normal intestinal flora were weaned onto either an OA-containing or a conventional diet without OA. At 2 months of age the colonized rats showed an increased DTH reaction to OA, but they did not have any anti-OA antibodies in serum. The rats were then immunized intracutaneously with OA in Freund's complete adjuvant. After immunization the colonized rats fed the conventional diet had a significantly higher DTH reaction to OA and significantly higher serum levels of IgE anti-OA antibodies than the uncolonized rats on the same diet. The colonized rats eating the OA-containing diet showed a 73% decrease in the DTH reaction to OA and also significantly lower levels of IgE and IgG antibodies against OA compared with the colonized rats fed conventional diet. The dams colonized as adults by the OA-producing E. coli developed IgE anti-lipopolysaccharide antibodies in serum while the pups colonized via the dams at birth did not. Neonatal colonization with an E. coli strain producing OA resulted in increased DTH reactivity against OA and priming for secondary IgE anti-OA response. Feeding the animals an OA-containing diet from weaning abrogated this intestinally induced hypersensitivity and rendered the animals orally tolerant to OA.

Animals↗
PubMed1993

Immune cell distribution in the small intestine of the pig: immunohistological evidence for an organized compartmentalization in the lamina propria.

Using monoclonal antibodies in immunohistochemistry, the distribution of the cells with the following surface antigens was studied in samples of proximal and distal small intestine of five 6-month-old pigs: CD2, CD4 (helper/inducer T-cells), CD8 (suppressor/cytotoxic T cells), accessory cell marker (monocyte/granulocyte), MHC Class II (DRw), and interleukin 2 (IL-2) receptor. CD2+ cells were found in high numbers in both the epithelium and the lamina propria. More cells were demonstrated in villis than in crypts (proportion approximately 4:1). At least two subpopulations of intraepithelial lymphocytes were identified: apically in the epithelium there were CD2+CD4-CD8- (double negative) cells, whereas cells expressing CD8 marker were concentrated around the basement membrane. CD4+ cells were localized in the lamina propria towards the villus core. Accessory cells were distributed in crypts and the villus base and more cells were found in ileum than in duodenum. In contrast, MHC Class II+ cells were located predominantly in villi, just underneath the basement membrane, forming a sheath of cells between the CD8+ and the CD4+ cells. Cells expressing IL-2 receptor were sparse but widely distributed in both the lamina propria and the epithelium. This organized cell distribution may be related to the physiology of the mucosal immune system in the gut.

Animals↗
PubMed1993

Specific immunological unresponsiveness following active primary responses to proteins in the weaning diet of piglets.

Young piglets weaned onto soya diets frequently develop diarrhoea which may have a dietary and/or immunological component. Piglets abruptly weaned onto soya at 3 weeks of age developed levels of serum IgG anti-soya antibodies almost comparable to those induced by injection with soya protein in adjuvant at 7 weeks. In the piglets primed by feeding, no significant further increase in antibody occurred after subsequent systemic injection. In contrast, secondary responses were observed in age-matched animals, previously primed by injection, and primary responses were obtained in previously naive piglets. The results demonstrate the development of specific unresponsiveness to soya proteins in neonates fed soya, despite the occurrence of an initial vigorous immune response to the fed protein.

Administration, Oral↗