SABIIA - Sistema Aberto e Integrado de Informação em Agricultura (Sabiia)

Verdolin,B.A.; Ficker,S.M.; Faria,A.M.C.; Vaz,N.M.; Carvalho,C.R..

Initial contacts with a T-dependent antigen by mucosal routes may result in oral tolerance, defined as the inhibition of specific antibody formation after subsequent parenteral immunizations with the same antigen. We describe here an additional and permanent consequence of these initial contacts, namely, the blockade of secondary-type responsiveness to subsequent parenteral contacts with the antigen. When repeatedly boosted ip with small doses (3 µg) of ovalbumin (OVA) (or lysozyme), primed B6D2F1 mice showed progressively higher antibody responses. In contrast, mice primed after a single oral exposure to the antigen, although repeatedly boosted, maintained their secondary antibody titers on a level which was inversely proportional to the dose of antigen...

Aging and immunoglobulin isotype patterns in oral tolerance

Palavras-chave: Oral tolerance; Mucosal immunity; Stability; Memory.

Ano: 2001

URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2001000200008

Faria,A.M.C.; Ficker,S.M.; Speziali,E.; Menezes,J.S.; Stransky,B.; Verdolin,B.A.; Lahmann,W.M.; Rodrigues,V.S.; Vaz,N.M..

In the present review we address oral tolerance as an important biological phenomenon and discuss how it is affected by aging. Other factors such as frequency of feeding and previous digestion of the antigen also seem to influence the establishment of oral tolerance. We also analyze immunoglobulin isotypes of specific antibodies formed by tolerant and immunized animals of different ages submitted to different conditions of oral antigen administration. Isotypic patterns were studied as a parameter for assessing the pathways of B and T cell interactions leading to antibody production

Ethanol-induced colitis prevents oral tolerance induction in mice

Palavras-chave: Oral tolerance; Aging; Isotypes; Gut; Mucosa.

Ano: 1998

URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X1998000100005

Andrade,M.C.; Vaz,N.M.; Faria,A.M.C..

The gut mucosa is a major site of contact with antigens from food and microbiota. Usually, these daily contacts with natural antigens do not result in inflammatory reactions; instead they result in a state of systemic hyporesponsiveness named oral tolerance. Inflammatory bowel diseases (IBD) are associated with the breakdown of the immunoregulatory mechanisms that maintain oral tolerance. Several animal models of IBD/colitis are available. In mice, these include targeted disruptions of the genes encoding cytokines, T cell subsets or signaling proteins. Colitis can also be induced by intrarectal administration of chemical substances such as 2,4,6-trinitrobenzene sulfonic acid in 50% ethanol. We report here a novel model of colitis induced by intrarectal...

IgA response in serum and gut secretion in sensitized mice fed with the dust mite Dermatophagoides pteronyssinus extract

Palavras-chave: Ethanol; Colitis; Oral tolerance; Cytokines.

Ano: 2003

URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2003000900013

Maciel,M.; Fusaro,A.E.; Oliveira,C.R.; Futata,E.A.; Duarte,A.J.S.; Sato,M.N..

Induced oral tolerance to mucosal-exposed antigens in immunized animals is of particular interest for the development of immunotherapeutic approaches to human allergic diseases. This is a unique feature of mucosal surfaces which represent the main contact interface with the external environment. However, the influence of oral tolerance on specific and natural polyreactive IgA antibodies, the major defense mechanism of the mucosa, is unknown. We have shown that oral administration of an extract of the dust mite Dermatophagoides pteronyssinus (Dp) to primed mice caused down-regulation of IgE responses and an increase in tumor growth factor-ß secretion. In the present study, we observed that primed inbred female A/Sn mice (8 to 10 weeks old) fed by gavage a...

Indirect effects of oral tolerance to ovalbumin interfere with the immune responses triggered by Schistosoma mansoni eggs

Palavras-chave: Mucosa; Atural IgA antibodies; Oral tolerance; Cytokines; Allergy; Dermatophagoides pteronyssinus.

Ano: 2004

URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2004000600006

Carvalho,C.R.; Lenzi,H.L.; Correa-Oliveira,R.; Vaz,N.M..

The objective of the present study was to investigate whether the injection of a tolerated protein (indirect effects) affects the formation of granulomas around Schistosoma mansoni eggs trapped in the lungs after intravenous (iv) injection into normal (noninfected) C57BL/6 mice (6 animals per group). To induce oral tolerance to chicken egg ovalbumin a 1/5 dilution of egg white in water was offered ad libitum in a drinking bottle for 3 days. Control mice received water. After 7 days, control and experimental animals were injected iv with 2,000 S. mansoni eggs through a tail vein. In some mice of both groups the iv injection of eggs was immediately followed by intraperitoneal (ip) immunization with 10 µg of dinitrophenylated conjugates of ovalbumin (DNP-Ova)...

Interruption of recently induced immune responses by oral administration of antigen

Palavras-chave: Oral tolerance; Ovalbumin; Granuloma; Schistosoma mansoni.

Ano: 2002

URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2002001000012

Conde,A.A.; Stransky,B.; Faria,A.M.C.; Vaz,N.M..

Interest in oral tolerance has been renewed in the last few years as a possibility of intervention in human autoimmune diseases. An obstacle in this direction is that, although easily induced in animals virgin of contact with the antigen, oral tolerance becomes hard to induce in previously immunized animals. The present results show that there is an early period after primary immunization in which prolonged oral exposure to the antigen may arrest ongoing immune responses. Beyond this period, oral exposures to the antigen become ineffective and may actually boost immune responses. The end of the susceptible period coincides with the emergence of free specific antibodies in serum. However, the previous administration of purified anti-ovalbumin antibodies (40...

Oral tolerance induction with altered forms of ovalbumin

Palavras-chave: Suppression; Antibody response; Oral tolerance; Ovalbumin.

Ano: 1998

URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X1998000300008

Stransky,B.; Faria,A.M.C.; Vaz,N.M..

As a T cell-dependent phenomenon, oral tolerance is not expected to depend necessarily on native configuration of antigens. We investigated the induction of oral tolerance with modified ovalbumin (Ova). Oral administration of heat-denatured (HD-Ova) and cyanogen bromide-degraded ovalbumin was less effective than native Ova in inducing oral tolerance in B6D2F1 mice. HD-Ova was effective in suppressing delayed-type hypersensitivity (DTH) reactions but did not suppress specific antibody formation. Injection of Ova directly into the stomach, but not into the ileum or cecum, suppressed subsequent immunization to DTH reactions. Gavage with protease inhibitors (aprotinin or ovomucoid) before gavage with Ova was ineffective in blocking tolerance induction....

Coupling of palmitate to ovalbumin inhibits the induction of oral tolerance

Palavras-chave: Antigen; Digestion; Oral tolerance; Mouse; Ovalbumin.

Ano: 1998

URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X1998000300009

Oliveira,F.M.; Silva-Neto,A.F.; Silva,C.A.; Gontijo,C.M..

Oral tolerance is a phenomenon that may occur in animals exposed to protein antigens for the first time by the oral route. They become unable to produce immune responses at the levels normally observed when they are immunized parenterally with antigen in the presence of adjuvants. Lipids have been used as adjuvants for both parenteral and oral immunization. In the present study we coupled ovalbumin with palmitate residues by incubating the protein with the N-hydroxysuccinimide palmitate ester and tested the preparation for its ability to induce oral tolerance. This was performed by giving 20 mg of antigen to mice by the oral route 7 days prior to parenteral immunization in the presence of Al(OH)3. Mice were bled one week after receiving a booster that was...

Effect of aging and oral tolerance on dendritic cell function

Palavras-chave: Oral tolerance; Lipid-protein conjugates; Antigen absorption; Gut mucosa; Ovalbumin.

Ano: 1998

URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X1998001100009

Simioni,P.U.; Fernandes,L.G.R.; Gabriel,D.L.; Tamashiro,W.M.S.C..

Oral tolerance can be induced in some mouse strains by gavage or spontaneous ingestion of dietary antigens. In the present study, we determined the influence of aging and oral tolerance on the secretion of co-stimulatory molecules by dendritic cells (DC), and on the ability of DC to induce proliferation and cytokine secretion by naive T cells from BALB/c and OVA transgenic (DO11.10) mice. We observed that oral tolerance could be induced in BALB/c mice (N = 5 in each group) of all ages (8, 20, 40, 60, and 80 weeks old), although a decline in specific antibody levels was observed in the sera of both tolerized and immunized mice with advancing age (40 to 80 weeks old). DC obtained from young, adult and middle-aged (8, 20, and 40 weeks old) tolerized mice were...