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U Dahlgren

Publications and source records attributed to U Dahlgren.

46 records · Page 3Linked to original sources
PubMed1983

IgA antibodies in rat bile are not solely derived from thoracic duct lymph.

The IgA level in rat bile was significantly decreased by drainage of the thoracic duct, and passively administered IgA antibodies to Escherichia coli O antigen decreased similarly. In contrast, specific IgA antibodies against E. coli O antigen raised by immunization in the Peyer's patches did not diminish significantly in the bile. Rats immunized in the Peyer's patches with sheep erythrocytes had IgA-forming cells in the thoracic lymph nodes, in the mesenteric lymph nodes, and in the spleen. Perfusion of the liver of immunized animals significantly decreased the bile levels of the IgA antibodies. It seems that IgA antibodies reach the bile not only via the thoracic duct but also via lymph ducts originating from thoracic lymph glands and the spleen.

Animals↗
PubMed1982

The mucosal immune response in the neonate.

Human infants are relatively deficient in the IgA system defending mucosal membranes, but are provided via the maternal milk with considerable amounts of SIgA directed against microbes and food antigens to which both mother and infant are exposed. It is possible that serum antibodies may support the mucosal defense as do the lactoferrin, lysozyme and other defense factors present in the milk.

Animals↗
PubMed1981

Dimeric IgA in the rat is transferred from serum into bile but not into milk.

Intravenous administration of ductus thoracicus lymph with dimeric IgA antibodies against Escherichia coli 06 to lactating rat dams did not result in transfer of IgA antibodies into the milk, although the antibodies were detectable in serum 1 min after the administration and in bile 60 min later. After intravenous injection of serum from bile-duct-occluded (BDO) rats immunized in the Peyer's patches into lactating rat dams. IgA antibodies appeared in the serum and remained there up to 230 min. At this time no IgA antibodies were seen in the milk while they were present in bile. IgG and IgM 06 antibodies did not appear in bile or milk after intravenous administration of lymph or serum from BDO rats.

Animals↗
PubMed1979

The secretory IgA system in the neonatal period.

It is still not known when the secretory IgA response, important for defence of the mucous membranes, becomes fully competent in the human infant. The infant is, however, provided with 0.25--0.5 g of secretory IgA/day via the maternal milk. The milk contains secretory IgA antibodies against a wide variety of antigens from microorganisms, including bacteria, viruses and parasites. Many of the antibodies are directed against important virulence factors such as bacterial pili, enterotoxins, capsular polysaccharides and endotoxic lipopolysaccharides. The passive transfer of antibodies through the milk may explain why breast-fed infants are resistant to enteric infections in particular. The antibodies in the milk are often directed against antigens in the mother's milieu and intestine. An entero-mammary gland link, possibly consisting of lymphoid cells homing from the Peyer's patches in the intestine to the mammary gland, has been suggested. A limited selective uptake of oligomeric IgA from serum in exocrine glands, including the mammary glands, has also been indicated. Whichever the mechanism, the antibodies transferred via breast milk are composed to meet the needs of the infant.

Adolescent↗
PubMedDate not supplied

Defence of mucous membranes by antibodies, receptor analogues and non-specific host factors.

Most infections reach man via the mucosal membranes, and more than half of the lymphoid system is found in connection with mucosae. The major antibodies found on mucous membranes are secretory IgA, which function primarily by binding microorganisms and thereby preventing their contact with the host tissues. The optimal mode of immunization to obtain a secretory IgA response is not well defined. Repeated mucosal exposure with antigen may result in oral tolerance, with decreasing circulating antibodies but a remaining secretory IgA response. The secretory IgA response is usually short-lived and can be difficult to boost. IgM as well as IgG antibodies may add to host defence at the mucosal level, but when engaged, they usually induce inflammation in host tissues. Analogues to bacterial receptors on mucosal epithelium may be present in exocrine secretions such as human milk. During an attack on the host, it is possible that such receptor analogues may aid in the prevention of attachment of bacteria to mucous membranes used as an initial site. A number of non-specific host factors support mucosal defence. One of them is lactoferrin. Lactoferrin deficiency seems to result in recurrent bacterial infections, suggesting its importance in normal host defence.

Administration, Oral↗
PubMedDate not supplied

The secretory IgA system.

The secretory IgA system is common to all mucosal membranes and is presumably of great importance for their defense. In addition to the secretory IgA antibodies produced in a mucosa in response to a local antigenic stimulus there is a spread of this type of IgA response via committed lymphocytes. They originate from central lymphoid organs in the intestinal (Peyer's patches) and bronchial mucosa (bronchus-associated lymphoid tissue, BALT) which they leave after antigenic exposure. They migrate, or "home", to exocrine glands such as the lacrimal, salivary, mammary and prostatic glands and mucosal membranes of the respiratory, gastrointestinal and genito-urinary tract. Almost half of all lymphocytes may be involved in the production of IgA antibodies. The secretory IgA antibodies are the dominating immunoglobulins in exocrine secretions on mucous membranes. They function primarily by preventing contact between the microbe and the host tissue most commonly attacked in infections, the mucous membrane. The fact that breast-feeding protects the infant against intestinal infections is one good example of the clinical significance of secretory IgA antibodies. This mode of protection can be enhanced by vaccination.

Breast Feeding↗
PubMedDate not supplied

Food allergens transformed into tolerogens.

Antigen presentation determines immunologic outcome, and by modifying the presentation of allergen to the host one can prevent an allergic response. Under certain conditions, covalent linkage, of ovalbumin to rat IgG, a molecule already tolerated by the host, can make a protein-IgG conjugate which down-regulates the immune response to this food allergen. The suppression is allergen specific. It affects both T and B cell immune responses. Administration of allergens linked to isologous IgG may provide a novel strategy for allergy prevention.

Allergens↗