The induction of tolerance to a soluble protein antigen by oral administration

The repeated administration of bovine serum albumin by stomach tube to Charles River and Black Norwegian rats resulted in a state of partial tolerance to the antigen. A very small amount of antibody was detected in the serum at the end of the oral regime but anti-BSA-producing cells could not be demonstrated in the lamina propria, in the Peyer's patches of the small intestine, in the mesenteric nodes or in the spleen of these animals. Antibody was not demonstrated in the small intestinal contents or in the faeces of the same animals.     

Enhanced immunological tolerance against allograft rejection by oral administration of allogeneic antigen linked to cholera toxin B subunit

A single oral intragastric administration of cholera toxin B subunit (CTB) conjugated to allogeneic thymocytes (ATC, 4 x 10(7) cells) under conditions allowing the CTB to bind the complex to GM1 ganglioside receptors was shown to be efficacious in inducing peripheral T cell tolerance associated with significant suppression of both primary and secondary accelerated rejection of heart allografts when tested in mice. Allogeneic in vivo delayed-type hypersensitivity (DTH), in vitro cytotoxicity responses, and mixed lymphocyte reactions (MLR) by T cells from mesenteric lymph nodes (MLN), popliteal lymph nodes (PLN), and spleen were significantly reduced in mice treated with the CTB-ATC conjugate, as were also the numbers of cells in these organs producing IL-2, IFN-gamma, or IL-4. In contrast, a marked increase in the production of IL-4 in Peyer's patches (PP) and of TGF-beta(1) in PLN was observed. The suppressive potential of T cells from PP and/or MLN after oral treatment with CTB-ATC was further evident by intraperitoneal transfer of such cells from CTB-ATC-treated animals to primed recipients, which led to marked suppression of both allogen-specific DTH and MLR responses. A critical role for PP in inducing peripheral tolerance after oral CTB-ATC treatment was indicated by the absence of tolerance induction in animals whose PP had been destroyed before treatment with CTB-ATC. The results indicate that the protection against allograft rejection by oral treatment with CTB-ATC is mediated by T cells and associated with a strong induction of IL-4 production at mucosal sites and TGF-beta(1) at the effector sites.     

胸腺内注射同种异体抗原抑制坐骨神经移植排斥反应的免疫学研究

目的:探讨胸腺内注射同种异体MHC抗原对同种异体坐骨神经移植的效应.方法:以C57BL/6(H-2b)为供体,BALB/c(H-2d)为受体,将受体鼠分为4组:Ⅰ:自体移植组、Ⅱ:异体移植组、Ⅲ:异体移植加用免疫抑制剂组、Ⅳ:胸腺内注射组:坐骨神经移植前2周将供体MHC抗原提取物注射到受体鼠的胸腺内,移植后3周进行IL-2R、TNF-α、MLR、细胞凋亡等免疫学的检测.结果:胸腺内注射组小鼠的各项免疫指标与异体移植组相比具有统计学意义.结论:胸腺内注射同种异体抗原对抑制同种异体神经移植排斥反应具有一定作用.     

Effects of oral administration of interferon-alpha on antibody production in mice with induced tolerance.

In vivo systemic effects and the immunomodulating potential of the oral administration of murine interferon-alpha (IFN-alpha) were investigated through mRNA expression of both IFN-alpha-inducible factors, interferon regulatory factor-1 (IRF-1) and 2,5-adenylate synthetase [2-5(A) synthetase] and 2-5(A) synthetase enzymatic activity in spleen and antibody production. The daily administration of IFN-alpha (0.1, 1, 10, and 100 IU/body) for 1 week augmented IRF-1 and 2-5(A) synthetase mRNA expression levels, as well as 2-5(A) synthetase enzymatic activity in spleen cells but not in cervical lymph nodes. The in vivo immunomodulating potential of the oral administration of IFN-alpha was also evaluated through antibody production in mice with induced tolerance. Ovalbumin (OVA) was administered intraperitoneally (i.p.) to induce systemic antibody production on day 0 when OVA feeding was initiated. The OVA was fed every 2-3 days for a total of 14 doses to suppress serum antibody levels. Oral administration of murine IFN-alpha was initiated on day 0 and was continued for 5 consecutive days weekly for 5 weeks (24 doses). On every sampling date (days 10, 17, 24, and 32), specific antibody levels in the IFN-alpha-administered groups were significantly higher than those in the control (nonadministered) group. This was especially noted in early phases (days 10 and 17) of antibody production when the levels of antibody in serum from the IFN-alpha-administration groups were equivalent to those of the nontolerance group. Altogether, it is suggested that oral use of IFN-alpha can elicit immunomodulating actions (e.g., antibody levels) by affecting the systemic immune system(s).     

B cell tolerance induced by polymeric antigens. VI. Kinetics and reversibility of the inhibition of antibody-forming cells by antigen.

Injection of mice already making antibodies to 2,4-dinitrophenylated (DNP) Ficoll with tolerizing doses of DNP-pneumococcal polysaccharide (DNP-lys-S3) markedly inhibits the secretion of anti-DNP antibodies by IgM antibody-forming cells. The present study shows that the degree of inhibition depends not only on the dose of DNP-lys-S3 but also on the duration of exposure to antigen. DNP-lys-S3 was detectable on the surface of antibody-forming cells at a time when their rate of secretion was unimpaired, thus suggesting that the inhibition involves intracellular events subsequent to the binding of antigen to the cell membrane. The inhibition was reversible if antibody-forming cells were exposed to antigen for 24 h, and then cultured for 18 h in its absence, but became irreversible if the treatment period was extended to 48 h. The relevance of this model of inhibition of lymphocyte function by antigen to possible mechanisms of B cell tolerance is discussed.     

Visualizing the T-cell response elicited by oral administration of soluble protein antigen

Oral administration of soluble protein antigen induces tolerance, while particulate antigens encountered in the intestine provoke active immunity. Although the events that lead to these distinct outcomes are not yet fully characterized, they may reflect differences at the antigen-presenting cell (APC) level. The role of dendritic cells (DC) in regulating responses at mucosal sites has remained largely undefined because of the low frequency of DC in mucosal-associated tissues. In this study we have used the growth factor Flt3-ligand (Flt3L) to expand DC populations in vivo, in combination with an adoptive transfer system, in order to track antigen-specific T cells during oral tolerance induction. We observed rapid T-cell activation, localized particularly in the mucosal tissues, within hours after feeding the soluble protein antigen, ovalbumin (OVA). The response was enhanced in Flt3L-treated mice, indicating an important role for DC during the inductive phase of tolerance.     

Adaptive T-cell responses regulating oral tolerance to protein antigen

The term oral (or mucosal) tolerance has been classically defined as the suppression of T- and B-cell responses to an antigen by prior administration of the antigen by the oral route. In recent years, it has become clear that both innate and acquired regulatory immune responses are essential for the development of oral tolerance. As such, mucosal microenvironmental factors such as transforming growth factor- β, prostaglandins but also dietary vitamin A create conditioning of an adaptive regulatory T-cell response that suppresses subsequent antigen-specific responses. Particular resident subsets of antigen presenting dendritic cells are pivotal to convey conditioning signals next to the presentation of antigen. This review discusses the primary mechanisms of adaptive regulatory T-cell induction to ingested soluble protein antigen. However, we also discuss the limitations of our knowledge with respect to understanding the very common food hypersensitivity Celiac disease caused by an aberrant adaptive immune response to the food protein gluten.     

Regulation of oral antigen delivery early in life: Implications for oral tolerance and food allergy

The increasing incidence of food allergy remains a significant public health concern. Food allergy is partially due to a lack, or loss of tolerance to food allergens. Clinical outcomes surrounding early life practices, such as breastfeeding, antibiotic use and food allergen exposure, indicate the first year of life in children represents a unique time for shaping the immune system to reduce allergic outcomes. Animal models have identified distinctive aspects of when and where dietary antigens are delivered within the intestinal tract to promote oral tolerance prior to weaning. Additionally, animal models have identified contributions from maternal proteins from breast milk and bacterial products from the gut microbiota in regulating dietary antigen exposure and promoting oral tolerance, thus connecting decades of clinical observations on the benefits of breastfeeding, early food allergen introduction and antibiotic avoidance in the first year of life in reducing allergic outcomes. Here, we discuss how exposure to gut luminal antigens, including food allergens, is regulated in early life to generate protective tolerance and the implications of this process for preventing and treating food allergies.     

Autoimmune disease induced by oral administration of mercuric chloride in Brown-Norway rats

Only few reports are available on the consequences of chronic oral administration of low doses of mercuric chloride (HgCl2). Forty Brown-Norway rats received 150 micrograms HgCl2/100 g body weight 3 times a week by gavage or by i.m. injection with 100 micrograms twice per week. After 2 weeks of oral HgCl2 administration, the rats lost weight and hair. Phases of proteinuria were observed in weeks 5-8 and then continuously from week 12 until the end of the experiment at week 39. Antibodies binding to renal, intestinal, and vascular basement membrane developed after 2 weeks; circulating immune complexes were detectable in increasing titers starting at week 3. There were linear deposits of IgG, IgM, and IgA in the glomerular basement membrane and tubular basement membrane, and along the intestinal basement membrane. After week 11, the first granular immune deposits were observed in renal and intestinal basement membranes. Light microscopy showed thickening of glomerular basement membrane, mesangial matrix, and tubular basement membrane. In addition, interstitial nephritis was observed in some animals. Interestingly, kidney involvement was as severe in the orally as the i.m.-treated animals.     

空弯菌抗原诱导的自身抗体产生动力学

用CJ-S131菌苗经口免疫小鼠16周,观察免疫小鼠体内的自身抗体(抗ds-DNA,ss-DNA,组蛋白和ENA抗体)产生动力学。在CJ-S131菌苗连续免疫的16周内,免疫小鼠有两个自身抗体产生峰。免疫后第6周,出现第一峰,抗组蛋白和ENA抗体的阳性率高于抗ds-DNA和ss-DNA抗体;在第16周,抗ds-DNA和ss-DNA抗体的阳性率高于抗组蛋白和ENA抗体。在正常小鼠体内,存在“自然”抗核酸抗体(抗ds-DNA和ss-DNA抗体),随年龄而增长,但个体差异较大;而抗核蛋白抗体(抗组蛋白和ENA抗体)始终测不出。上述结果提示,抗组蛋白抗体和抗ENA抗体在自身免疫病的发病机理和早期诊断中,具有潜在意义,值得进一步研究。     

Mechanism of tolerance toSalmonella typhi Vi antigen induced with cyclophosphamide

Treatment with Vi antigen followed after 46–48 h by cyclophosphamide induces a state of specific areactivity in mice which persists through adoptive transfer. Only trace amounts of Vi antigen were found in the blood and spleen of the tolerant mice after 2–3 weeks. No T suppressors were found in the spleen of the tolerant animals: Cells of the tolerant mice did not depress the immune response of normal lymphocytes when cultured togetherin vivo and they did not induce tolerance in intact recipients; the cells of normal donors partially restored the immunoreactivity of the tolerant animals. The results suggest that this form of tolerance is due to elimination or prolonged inactivation of the immunocompletent cells.Laboratory of Immunological Tolerance, N. F. Gamaleya Institute of Epidemiology and Microbiology, Academy of Medical Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR P. A. Vershilova.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 83, No. 4, pp. 440–443, April, 1977.     

Characteristics of immunity induced by viral antigen or conferred by antibody via different administration routes

The characteristics of the immunity induced by viral antigens or conferred by antiviral antibody via different routes of administration were evaluated comparatively. C57BL/6 mice were immunized via intranasal, intradermal or enteric routes with a live recombinant vaccinia virus expressing the respiratory syncytial virus (RSV) F glycoprotein (F.rVV) or RSV, and then challenged intranasally with RSV. Inhibition of RSV replication was observed in the lungs of all the mice; however, only intranasal immunization hindered virus replication in the nose. Lung inflammation, characterized by infiltration of neutrophils and of mononuclear cells was strongest in the intradermally immunized mice, but was observed in all F.rVV immunized mice to various degrees. Intranasal administration of a potently neutralizing human anti-RSV antibody Fab fragment to infected mice inhibited RSV replication in the nose and, when combined with intraperitoneal administration, protected both the lung and the nose in the absence of deleterious lung pathology. These data suggest that intranasal immunization with F.rVV reduces RSV replication in the respiratory tract, but still induces pathological lung inflammation, even though this is milder than that observed following intradermal immunization. Local neutralizing antibody is indispensable for protection in the nose.     

Rat urinary bladder hyperplasia induced by oral administration of carbonic anhydrase inhibitors.

The carbonic anhydrase inhibitors, acetazolamide and MK-0927, were given by oral route to male Sprague-Dawley rats at 200 mg/kg/day and 25 mg/kg/day, respectively, for up to 4 weeks. Sequential necropsies were performed and urinary bladders were examined by light microscopy (LM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Similar urinary bladder changes were seen with both compounds. SEM evidenced slight multifocal urothelial changes consisting of cell swelling, dissociation, degeneration, and exfoliation after 3 and 5 days of treatment. After 2 and 4 weeks of treatment, elevated or leafy microridges on the luminal cell surfaces were seen together with foci of swollen cells. After a 2-month-recovery-period, the urothelial surfaces were normal. LM and TEM showed multifocal vacuolation of the urothelium associated with inflammation of the underlying lamina propria after 3 and 5 days of treatment. Cellular hypertrophy and hyperplasia of the transitional epithelium was seen after a 5-day treatment, persisted without increasing severity after 2 and 4 weeks of treatment, and totally regressed after the recovery period. It was concluded that, in the rat urinary bladder, oral administration of acetazolamide and MK-0927 induced early degeneration and inflammation followed by epithelial regeneration, resulting in a reversible hyperplasia of the transitional epithelium.     

Immune tolerance induced by polyethylene glycol-conjugate of protein antigen: clonal deletion of antigen-specific Th-cells in the thymus

Polyethylene glycol (PEG) conjugates of protein antigens induce antigen-specific immune tolerance of helper T (Th)-cells. However, the mechanism of this Th-cell tolerance has remained unelucidated. Using transgenic mice with ovalbumin (OVA)-specific T-cell receptor (TCR) genes, we examined the response of OVA-specific Th-cells towards tolerogenic PEG-conjugate of OVA in vitro and in vivo. When stimulated with PEG--OVA in vitro, transgenic OVA-specific Th-cells proliferated and produced interleukin 2, the levels of which were comparable to those induced by unmodified OVA. In contrast, PEG--OVA administered into the circulation of transgenic mice induced unresponsiveness in peripheral OVA-specific Th-cells. Moreover, in the thymus of these transgenic mice, the frequency of immature CD4+CD8+ (double positive) thymocytes was reduced. A similar phenomenon was not observed in transgenic mice treated with unmodified OVA. As autoreactive T-cells are known to be clonally deleted at the immature double positive stage in the thymus. Th-cell tolerance induced by PEG--protein antigens is at least in part mediated by central tolerance in the thymus, and is likely caused by the markedly enhanced stability of PEG--protein conjugates in the circulatory system.     

Pulmonary dendritic cells producing IL-10 mediate tolerance induced by respiratory exposure to antigen

Respiratory exposure to allergen induces T cell tolerance and protection against the development of airway hyperreactivity and asthma. However, the specific mechanisms by which tolerance is induced by respiratory allergen are not clear. We report here that pulmonary dendritic cells (DCs) from mice exposed to respiratory antigen transiently produced interleukin 10 (IL-10). These phenotypically mature pulmonary DCs, which were B-7(hi) as well as producing IL-10, stimulated the development of CD4(+) T regulatory 1--like cells that also produced high amounts of IL-10. In addition, adoptive transfer of pulmonary DCs from IL-10(+/+), but not IL-10(-/-), mice exposed to respiratory antigen induced antigen-specific unresponsiveness in recipient mice. These studies show that IL-10 production by DCs is critical for the induction of tolerance, and that phenotypically mature pulmonary DCs mediate tolerance induced by respiratory exposure to antigen.     

Immune tolerance induced by polyethylene glycol-conjugate of protein antigen: Clonal deletion of antigen-specific Th-cells in the thymus

Polyethylene glycol (PEG) conjugates of protein antigens induce antigen-specific immune tolerance of helper T (Th)-cells. However, the mechanism of this Th-cell tolerance has remained unelucidated. Using transgenic mice with ovalbumin (OVA)-specific T-cell receptor (TCR) genes, we examined the response of OVA-specific Th-cells towards tolerogenic PEG-conjugate of OVA in vitro and in vivo. When stimulated with PEG-OVA in vitro, transgenic OVA-specific Th-cells proliferated and produced interleukin 2, the levels of which were comparable to those induced by unmodified OVA. In contrast, PEG-OVAadministered into the circulation of transgenic mice induced unresponsiveness in peripheral OVA-specific Th-cells. Moreover, in the thymus of these transgenic mice, the frequency of immature CD4+CD8+ (double positive) thymocytes was reduced. A similar phenomenon was not observed in transgenic mice treated with unmodified OVA. As autoreactive T-cells are known to be clonally deleted at the immature double positive stage in the thymus, Th-cell tolerance induced by PEG-protein antigens is at least in part mediated by central tolerance in the thymus, and is likely caused by the markedly enhanced stability of PEG-protein conjugates in the circulatory system.     

Alteration of oral carbohydrate tolerance during administration of a fiber-free formula diet

Summary Fiber-free formula diets are widely used for medical and experimental purposes. In healthy individuals no major changes of fasting blood glucose have been reported, whereas oral glucose tolerance tests indicate a deterioration of carbohydrate tolerance following ingestion of liquid diets containing certain sugars. We examined carbohydrate tolerance in normal subjects during prolonged administration of a fiber-free semisolid diet containing polysaccharides instead of sugars. In the first experiment, diet A (55% starch, 40% highly polyunsaturated fat, P/S 5.4, 15% protein) served as the sole source of energy for 4 weeks. During this time a progressive deterioration of carbohydrate tolerance was observed, indicated by a gradual increase of the postprandial glycemic response (area under the curve) from –316 to +3874 mg/dl × min without significant alteration of postprandial serum insulin concentrations. For the second study, nutrient relations of the diet were modified (diet B: 45% starch, 40% saturated fat, P/S 0.3, 15% protein). The changes of carbohydrate tolerance during 1 week of feeding diet B were similar to those seen in the first experiment. However, follow-up observations during a subsequent pharmacological trial showed that the changes of postprandial blood glucose curves were reversed within 2 weeks. This was associated with an enhanced serum insulin response. The reason for the different durations of the metabolic effects of diets A and B are not obvious from our data. The time course may have been influenced by the different nutrient intake. Fasting blood glucose concentrations were not sensitive enough to detect the deterioration of carbohydrate tolerance.     

Therapeutic efficacy induced by the oral administration of Agaricus blazei Murill against Leishmania amazonensis

The development of therapeutic alternatives to treat leishmaniasis has received considerable attention. The present study aimed to investigate the efficacy of the Agaricus blazei Murill water extract (AbM) to treat BALB/c mice infected with Leishmania amazonensis. First, a dose-titration curve was performed. The most well-defined concentration able to induce the most effective results in the infected animals, considering a daily administration of the product, was that of 100?mg?kg(-1)?day(-1). In this context, the AbM was administered orally, beginning on day 0 up to 20?days postinfection. Additional animals were treated with amphotericin B (AmpB, 5?mg?kg(-1)?day(-1)) by peritoneal route for the same period of time, while the control group received distilled water. The animals were evaluated at 14?weeks post-infection, at which time the parasitological and immunological parameters were analyzed. Mice treated with the AbM presented a 60?% reduction in the inflammation of infected footpads as compared to untreated control-infected mice. Moreover, in the treated mice, as compared to the untreated controls, approximately 60 and 66?% reductions could be observed in the parasite burdens of the footpad and draining lymph nodes, respectively. In addition, no parasites could be detected in the spleen of treated mice at week?14 postinfection. These treated animals produced significantly higher levels of interferon gamma (IFN-γ) and nitric oxide (NO), higher levels of parasite-specific IgG2a isotype antibodies, and lower levels of interleukin (IL)-4, and IL-10 in the spleen and lymph node cell cultures than did the controls. Differences could be observed by comparing animals treated with AbM to those treated with AmpB, as indicated by a significant reduction in tissue parasitism, higher levels of IFN-γ and NO, and lower levels of IL-4 and IL-10, as well as by a decreased hepatic toxicity. In conclusion, the present study's data show that the A. blazei Murill water extract presents a high potential for the treatment of leishmaniasis, although additional studies on mice, as well as on other mammal hosts, are warranted in an attempt to determine this extract's true efficacy as compared to other known therapeutic products.