The frequency of cells secreting interferon-gamma and interleukin-4, -5, and -10 in the blood and duodenal mucosa of children with cow's milk hypersensitivity

Food protein-induced enteropathy: a revision for the clinician

Food protein-induced enteropathy (FPE) belongs to non-IgE gastrointestinal mediated food allergies. FPE is a syndrome characterized by diarrhea, weight loss and failure to thrive in young infants. Cow milk is the culprit food that most frequently causes FPE. The prevalence of FPE has not been fully estimated, but it is relatively rare. The diagnosis is based on the clinical manifestations and histological findings through colonoscopy. Laboratory tests are somewhat helpful in the diagnosis, although there are no disease-specific findings. Allergy testing for food specific IgE is not routinely recommended. The cornerstone of the management of FPE is the removal of culprit food from the diet. FPE is usually a transient condition that resolves in most cases by 1-2 years of life. This review addresses the latest findings on FPE, including a practical guide to assist pediatricians treating children with FPE.

Food Protein-Induced Enterocolitis Syndrome, Allergic Proctocolitis, and Enteropathy

Food protein-induced enterocolitis (FPIES), allergic proctocolitis (FPIAP), and enteropathy (FPE) are among a number of immune-mediated reactions to food that are thought to occur primarily via non-IgE-mediated pathways. All three are typically present in infancy and are triggered most commonly by cow's milk protein. The usual presenting features are vomiting with lethargy and dehydration in FPIES; bloody and mucous stools in FPIAP; and diarrhea with malabsorption and failure to thrive in FPE. Diagnosis is based on convincing history and resolution of symptoms with food avoidance; confirmatory diagnostic testing other than food challenge is lacking. The mainstay of management is avoidance of the suspected inciting food, with interval challenge to assess for resolution, which usually occurs in the first years of life. Studies published in the past few years clarify common presenting features, report additional culprit foods, address potential biomarkers, and suggest new management strategies.

Serum cytokine pattern in young children with screening detected coeliac disease

Coeliac disease is an autoimmune disease characterized by inflammation localized to the small bowel, but less is known about systemic signs of inflammation. The aim was to measure cytokines of the T helper 1 (Th1) and T helper 2 (Th2) cell patterns in children with screening-detected coeliac disease before and after treatment with a gluten-free diet. Serum samples selected before and after the start of a gluten-free diet from 26 3-year-old children diagnosed with biopsy-proven coeliac disease and from 52 matched controls were assayed in an multiplex enzyme-linked immunosorbent assay (ELISA) for the 10 cytokines: interferon (IFN)-γ, interleukin (IL)-1β, IL-2, IL-4, IL-5, IL-8, IL-10, IL-12p70, IL-13 and tumour necrosis factor (TNF)-α. Among Th1 cytokines, IFN-γ and IL-12p70 were elevated significantly in children with coeliac disease compared to controls (P < 0·001 and P = 0·001, respectively). Similar findings were demonstrated for the Th2 cytokines IL-5 (P < 0·001), IL-10 (P = 0·001) and IL-13 (P = 0·002). No difference in cytokine levels between the two groups was found for TNF-α, IL-1β, IL-2, IL-4 and IL-8. After gluten-free diet, levels of IL-5, IL-12 and IL-10 decreased significantly (P < 0·001, P = 0·002 and P = 0·007) and IFN-γ levels were reduced (P = 0·059). Young children with coeliac disease detected by screening demonstrate elevated levels of serum cytokines at time of diagnosis. A prolonged systemic inflammation may, in turn, contribute to long-term complications known to be associated with untreated coeliac disease.

Indication of immune activation in patients with perceived food hypersensitivity

Majority of the patients with perceived food hypersensitivity have irritable bowel syndrome (IBS), and a significant proportion of IBS patients also attribute their gastrointestinal complaints to food items. Different factors such as disturbed intestinal fermentation, enteric dysmotility, post-infectious changes and altered microbial flora in the colon as well as psychological disturbances likely play a role in the pathophysiology and symptoms generation in patients with food hypersensitivity. In addition, a number of studies in these patient groups indicate that local, systemic and mucosal immune systems are activated. The question now is no longer intestinal immune activation, but how the immune system is activated in these patients. In the following review, the potential pathogenetic role of the immune system and evidence of immune activation are reported in patients with perceived food hypersensitivity.

Review article: intestinal lymphoid nodular hyperplasia in children--the relationship to food hypersensitivity

BACKGROUND

Lymphoid aggregates are normally found throughout the small and large intestine. Known as lymphoid nodular hyperplasia (LNH), these aggregates are observed especially in young children and are not associated with clinical symptoms being considered 'physiological'. In children presenting with gastrointestinal symptoms the number and size of the lymphoid follicles are increased. Patients suffering from gastrointestinal symptoms (i.e. recurrent abdominal pain) should systematically undergo gastroduodenoscopy and colonoscopy. With these indications LNH, especially of the upper but also of the lower gastrointestinal tract has been diagnosed, and in some children it may reflect a food hypersensitivity (FH) condition.

AIM

To review the literature about the relationship between LNH and FH, particularly focusing on the diagnostic work-up for LNH related to FH.

METHODS

We reviewed literature using Pubmed and Medline, with the search terms 'lymphoid nodular hyperplasia', 'food hypersensitivity', 'food allergy' and 'food intolerance'. We overall examined 10 studies in detail, selecting articles about the prevalence of LNH in FH patients and of FH in LNH patients.

RESULTS

Collected data showed a median of 49% (range 32-67%) LNH in FH patients and a median of 66% (range 42-90%) FH in LNH patients. Literature review pointed out that the most important symptom connected with LNH and/or FH was recurrent abdominal pain, followed by diarrhoea and growth retardation. Both LNH and FH are associated with an increase in lamina propria γ/δ+ T cells, but the mechanisms by which enhanced local immune responses causing gastrointestinal symptoms still remain obscure.

CONCLUSIONS

When assessing FH, we rely on clinical evaluation, including elimination diet and challenge tests, and endoscopic and immunohistochemical findings. Considering the possible co-existence of duodenal and ileo-colonic LNH, upper endoscopy can be recommended in children with suspected FH, especially in those presenting with additional upper abdominal symptoms (i.e. vomiting). Likewise, lower endoscopy might be additionally performed in patients with suspected FH and LNH of the duodenal bulb, also presenting with lower abdominal symptoms (i.e. recurrent abdominal pain).

Microbial exposures in infancy predict levels of the immunoregulatory cytokine interleukin-4 in Filipino young adults

OBJECTIVES

Infancy represents a window of development during which long-term immunological functioning can be influenced. In this study, we evaluate proxies of microbial exposures in infancy as predictors of interleukin-4 (IL-4) in young adulthood. IL-4 is an immunoregulatory cytokine that plays a role in the pathogenesis of atopic and allergic diseases.

METHODS

Data were obtained from 1,403 participants in the Cebu Longitudinal Health and Nutrition Survey, an ongoing population-based study in the Philippines. Relationships between microbial and nutritional environments in infancy and plasma IL-4 concentrations in adulthood were evaluated using tobit regression models.

RESULTS

Having older siblings and more episodes of respiratory illness in infancy significantly predicted lower concentrations of plasma IL-4 in adulthood. Unexpectedly, more episodes of diarrheal illness in infancy were associated with higher IL-4 in adulthood. Interactions between a composite household pathogen exposure score and the duration of exclusive breastfeeding approached significance. This interaction showed that the negative association between household pathogen exposure in infancy and adult IL-4 was only significant for individuals who had been exclusively breastfed for a short duration of time. Finally, currently living in an urban household was unexpectedly, negatively associated with adult IL-4. Associations were independent of early nutrition, socioeconomic status (SES), and urbanicity, as well as current measures of infection, body fat, SES, and smoking.

CONCLUSIONS

This study builds on a growing body of literature demonstrating that early ecological conditions have long-term effects on human biology by providing evidence that multiple proxies of microbial exposures in infancy are associated with adult IL-4.

Late type of bronchial response to milk ingestion challenge: a comparison of open and double-blind challenge

Background. In some asthmatics the food allergy, for example, to milk, can participate in their bronchial complaints. The role of food allergy should be confirmed definitively by food ingestion challenge performed by an open challenge with natural foods (OFICH) or by a double-blind placebo-controlled food challenge (DBPCFC). Objectives. To investigate the diagnostic value of these techniques for confirmation of a suspected milk allergy in bronchial asthma patients. Methods. In 54 asthmatics with a positive history and/or positive skin tests for milk the 54 OFICH, and DBPCFC, were performed in combination with spirometry. Results. The 54 patients developed 39 positive late asthmatic responses (LAR) and 15 negative asthmatic responses to OFICH and 40 positive LARs and 14 negative responses to DBPCFC. The overall correlation between the OFICH and DBPCFC was statistically significant (P < 0.01). Conclusions. This study has confirmed the existence of LAR to milk ingestion performed by OFICH and DBPCFC in combination with spirometry. The results obtained by both the techniques did not differ significantly. The OFICH with natural food combined with monitoring of objective parameter(s), such as spirometry, seems to be a suitable method for detection of the food allergy in asthmatics. The DBPCFC can be performed as an additional check, if necessary.

Intestinal epithelial barrier dysfunction in food hypersensitivity

Intestinal epithelial barrier plays a critical role in the maintenance of gut homeostasis by limiting the penetration of luminal bacteria and dietary allergens, yet allowing antigen sampling for the generation of tolerance. Undigested proteins normally do not gain access to the lamina propria due to physical exclusion by tight junctions at the cell-cell contact sites and intracellular degradation by lysosomal enzymes in enterocytes. An intriguing question then arises: how do macromolecular food antigens cross the epithelial barrier? This review discusses the epithelial barrier dysfunction in sensitized intestine with special emphasis on the molecular mechanism of the enhanced transcytotic rates of allergens. The sensitization phase of allergy is characterized by antigen-induced cross-linking of IgE bound to high affinity FcεRI on mast cell surface, leading to anaphylactic responses. Recent studies have demonstrated that prior to mast cell activation, food allergens are transported in large quantity across the epithelium and are protected from lysosomal degradation by binding to cell surface IgE and low-affinity receptor CD23/FcεRII. Improved immunotherapies are currently under study including anti-IgE and anti-CD23 antibodies for the management of atopic disorders.

Changes in intestinal mucosal immune barrier in rats with endotoxemia

AIM: To investigate the dysfunction of the immunological barrier of the intestinal mucosa during endotoxemia and to elucidate the potential mechanism of this dysfunction.

METHODS: Male Wistar rats were randomly distributed into two groups: control group and lipopolysaccharide (LPS) group. Endotoxemia was induced by a single caudal venous injection of LPS. Animals were sacrificed in batches 2, 6, 12 and 24 h after LPS infusion. The number of microfold (M)-cells, dendritic cells (DCs), CD4⁺ T cells, CD8⁺ T cells, regulatory T (Tr) cells and IgA⁺ B cells in the intestinal mucosa were counted after immunohistochemical staining. Apoptotic lymphocytes were counted after TUNEL staining. The levels of interleukin (IL)-4, interferon (IFN)-γ and forkhead box P3 (Foxp3) in mucosal homogenates were measured by ELISA. The secretory IgA (sIgA) content in the total protein of one milligram of small intestinal mucus was detected using a radioimmunological assay.

RESULTS: This research demonstrated that LPS-induced endotoxemia results in small intestinal mucosa injury. The number of M-cells, DCs, CD8⁺ T cells, and IgA⁺ B cells were decreased while Tr cell and apoptotic lymphocyte numbers were increased significantly. The number of CD4⁺ T cells increased in the early stages and then slightly decreased by 24 h. The level of IL-4 significantly increased in the early stages and then reversed by the end of the study period. The level of IFN-γ increased slightly in the early stages and then decreased markedly by the 24 h time point. Level of Foxp3 increased whereas sIgA level decreased.

CONCLUSION: Mucosal immune dysfunction forms part of the intestinal barrier injury during endotoxemia. The increased number and function of Tr cells as well as lymphocyte apoptosis result in mucosal immunodeficiency.

The epithelial gatekeeper against food allergy

The rapid rise of allergic disorders in developed countries has been attributed to the hygiene hypothesis, implicating that increased environmental sanitation in early childhood may be associated with higher incidence of hypersensitivity. Intestinal epithelial barriers play a crucial role in the maintenance of gut homeostasis by limiting penetration of luminal bacteria and dietary allergens, yet allowing antigen sampling via the follicle-associated epithelium for generation of tolerance. However, this intricate balance is upset in allergic intestines, whereby luminal proteins with antigenic properties gain access to the subepithelial compartment and stimulate mast cell degranulation. Recent studies demonstrated that food allergens were protected from lysosomal degradation, and were transported in large quantities across the epithelium by binding to cell surface IgE/CD23 (FcepsilonRII) that prevented the antigenic protein from lysosomal degradation in enterocytes. IL-4 (a Th2-type cytokine) not only increased production of IgE from B cells, but also upregulated the expression of CD23 on intestinal epithelial cells. Further studies indicated that CD23 was responsible for the bidirectional transport of IgE across epithelium. The presence of IgE/CD23 opens a gate for intact dietary allergens to transcytose across the epithelial cells, and thus foments the mast cell-dependent anaphylactic responses. The understanding of the molecular mechanism responsible for epithelial barrier defects may be helpful in designing novel therapies to treat food allergy and other allergic diseases.

Cow's milk protein-specific T-helper type I/II cytokine responses in infants with necrotizing enterocolitis

Enteral feeding, in particular with formula feeds, is associated with necrotizing enterocolitis (NEC). In this study, we have examined, in the systemic and mucosal immune compartments, for evidence of bovine milk antigen sensitization in infants with NEC. Eleven newborns with Bell's staging 2-3 NEC [median post-conceptional age 31 wk (range 27-41 wk)], 21 neonatal controls [33 (28-40) wk] and 15 infants undergoing intestinal resection or mucosal biopsy for non-inflammatory conditions [39 (34-42) wk] were studied. Spontaneous and antigen or mitogen elicited interferon-gamma (IFN-gamma) [T-helper type I (Th1)], interleukin (IL)-4 and IL-5 [T-helper type II (Th2)] responses were enumerated using single-cell enzyme-linked immunospot (ELISPOT) assay in peripheral blood (PBMC) or lamina propria mononuclear cells. NEC infants, compared with controls, showed a significant elevation in baseline PBMC cytokine secreting cells, vigorous mitogen responses (20- to 120-fold increase) for IFN-gamma, IL-4 and IL-5 (p < 0.001), strong responses to beta-lactoglobulin (betalg) (IFN-gamma > IL-4/IL-5, p < or = 0.001), and somewhat smaller casein responses. Similarly, in the lamina propria, a small but significant increase in spontaneous cytokine-secreting cells was detected in NEC infants (p < 0.01), with an IFN-gamma/IL-4 predominant phytohemagglutinin (PHA)/concanavalin-A (ConA) response. Three of nine NEC infants (but no controls) also showed a positive ELISPOT response to betalg (IFN-gamma only) but none to casein. We have thus demonstrated significant cow's milk protein (CMP) sensitization in NEC, at least in the systemic compartment (mixed Th1/Th2), with minimal mucosal activation in some cases. These novel findings provide a potential mechanism for a direct contributory role of CMP in the pathogenesis of NEC.

Polyunsaturated fatty acids support epithelial barrier integrity and reduce IL-4 mediated permeability in vitro

BACKGROUND

The intestinal mucosa functions as a barrier against harmful dietary and microbial antigens. An intact gut barrier forms a prerequisite for protection against infection and allergy. Both allergic and inflammatory mediators (e.g. IL-4, IFN-gamma) are known to compromise the epithelial barrier integrity by enhancing permeability. Breast milk provides protection against infection and allergy and contains polyunsaturated fatty acids (PUFA).

AIM OF THE STUDY

Although PUFA are commonly used in infant formulas their effect on intestinal barrier is still poorly understood. Therefore the effects of distinct PUFA (n-6: LA, GLA, DGLA, AA; n-3: ALA, EPA, DHA) and a fat blend with PUFA composition similar to that of the human breast milk fat fraction, on barrier integrity were investigated.

METHODS

Human intestinal epithelial cells (T84) were pre-incubated with individual PUFA or a lipase treated fat blend, with or without subsequent IL-4 exposure. Barrier integrity was evaluated by measuring transepithelial resistance and permeability. Membrane phospholipid composition was determined by capillary gas chromatography.

RESULTS

DGLA, AA, EPA, DHA and to a lesser extend GLA enhanced basal TER and strongly reduced IL-4 mediated permeability, while LA and ALA were ineffective. Furthermore, the lipase treated fat blend effectively supported barrier function. PUFA were incorporated in the membrane phospholipid fraction of T84 cells.

CONCLUSIONS

Long chain PUFA DGLA, AA, EPA and DHA were particularly effective in supporting barrier integrity by improving resistance and reducing IL-4 mediated permeability. Fat blends that release specific PUFA upon digestion in the gastrointestinal tract may support natural resistance.

Allergen-specific helper T cell response in patients with cow's milk allergy: Simultaneous analysis of proliferation and cytokine production by carboxyfluorescein succinimidyl ester dilution assay

BACKGROUND

The role of antigen-specific T cells in the allergic reaction to cow's milk or in tolerance induction is not yet fully understood.

OBJECTIVE

This study was designed to analyse both cow's milk protein (CMP)-specific T cell proliferation and cytokine production simultaneously in children with cow's milk allergy (CMA) in comparison with subjects with various allergic backgrounds.

METHODS

Carboxyfluorescein succinimidyl ester was used to detect cow's milk-specific T cells by flow cytometry. The intra-cytoplasmic cytokine production of these antigen-specific T cells was also analysed.

RESULTS

Significant differences of both CMP-specific CD4+ cell proliferation and cytokine production between CMA and non-allergic children were observed. While the proliferative responses of children who recently outgrew CMA were not significantly different from those of patients, the patterns of cytokine production were similar to those of non-allergic children.

CONCLUSION

These results suggest that the presence of CMP-specific T cell clones per se does not produce CMA, but that the T-helper type 2-skewed pattern of those T cells is associated with adverse reactions. Although it is not possible to distinguish between individual patients with and without CMA on the basis of CFSE assays, these results contribute to the understanding of the pathogenesis and tolerance induction of CMA.

Casein-specific immunoglobulins in cow's milk allergic patient subgroups reveal a shift to IgA dominance in tolerant patients

Differences in casein-specific immunoglobulin (Ig) G-subclass and IgA serum levels between reactive and tolerant patients may hint at the immunopathogenesis during tolerance development in cow's milk allergy (CMA). alpha-, beta- and kappa-casein-specific IgG(1), IgG(4), IgE and IgA serum levels were compared in clinically reactive and tolerized IgE-mediated (n = 15) and non-IgE-mediated (n = 14) CMA with delayed gastrointestinal symptoms, using enzyme-linked immunosorbent assay (ELISA) and immunoblot techniques. The median anti-casein IgE levels in clinically reactive IgE-mediated CMA patients (n = 9) were 140- to 180-fold higher than in tolerized patients (n = 6) and 160- to 200-fold higher than in controls (n = 10). Median alpha-, beta- and kappa-casein-specific IgG(1) and IgG(4) levels were nine- to 60-fold higher in reactive patients and five- to 60-fold in tolerized patients. Clinical tolerance in IgE-mediated CMA was thus associated with decreased casein-specific IgE, IgG(4) and IgG(1), whereas serum IgA anti-alpha -, beta- and kappa-casein remained practically unaltered. Tolerized cow's milk protein (CMP)-sensitive atopic dermatitis had, in particular, decreased kappa-casein-specific IgG(1) levels, compared with clinically reactive patients. The ELISA levels to immunoblot correlation profile for the alpha-, beta- and kappa-casein-specific IgE suggested that the IgE-mediated CMA patients predominantly reacted to tertiary alpha- and beta-casein epitopes whereas the IgE in non-IgE-mediated patients reacted to linearized alpha-, beta- and kappa-casein epitopes. Clinical tolerance in non-IgE-mediated CMA patients (n = 9) was associated with a four- to 10-fold decrease in casein-specific IgE levels, accompanied by a five- to eightfold decrease in IgG(1) and five- to 60-fold decrease in IgG(4) levels, whereas casein-specific IgA levels remained unaltered. Thus, tolerance in both patient groups was characterized by a generalized decreased humoral immune response to caseins, which induced a functional shift to IgA dominance.

Intestinal cytokine mRNA expression in delayed-type cow's milk allergy

OBJECTIVES

The aim of the study was to investigate the characteristics of intestinal immune activation (ie, a chemokine receptor and cytokine expression profile) in delayed-type cow's milk allergy (CMA) appearing in the form of gastrointestinal symptoms.

PATIENTS AND METHODS

In all biopsy samples taken from the duodenum and/or the terminal ileum, 30 were studied for the expression of interferon-gamma, transforming growth factor-beta, chemokine receptor (CCR)-4, CCR-5, IL-2, IL-6, IL-10, IL-12p35, IL-12p40 and IL-18 specific mRNA by real-time quantitative reverse transcriptase-polymerase chain reaction in 26 children ages 3 to 15 years: 10 with untreated delayed-type CMA, 6 with celiac disease (CD) and 10 controls.

RESULTS

The children with delayed-type CMA showed lower IL-2 and IL-18 mRNA expression in the duodenum (both P = 0.055) and higher CCR-4 and IL-6 mRNA expression in the terminal ileum (P = 0.055, P = 0.016) compared with the controls. The children with CD exhibited slightly higher expression of interferon-gamma and CCR-4 mRNA (P = 0.054, P = 0.053) and lower expression of IL-18 mRNA (P = 0.004) in the duodenal samples compared with the controls. The mRNA expression levels of regulatory cytokines, transforming growth factor-beta and IL-10 remained similar in all 3 groups.

CONCLUSIONS

The children with delayed-type gastrointestinal CMA showed a unique pattern of local intestinal hypersensitivity with Th2 response-related characteristics, a profile differing clearly from the children with CD.

Food antigen causes TH2-dependent enteropathy followed by tissue repair in T-cell receptor transgenic mice

BACKGROUND

Clarification of the mechanisms underlying the development of food-sensitive intestinal inflammation will provide an important clue to combating food allergies.

OBJECTIVE

To establish a model of intestinal inflammation caused by oral administration of antigen without additional treatments, we focused on the ovalbumin (OVA) 23-3 T-cell receptor transgenic mouse, which had been reported to have high serum antigen-specific IgE responses to the feeding of an egg white diet.

METHODS

Changes in body weight of mice fed an egg white diet were monitored throughout the 28-day experimental period. After the 28-day feeding, intestinal tissues were harvested for histologic examination. Endogenous production of cytokines and histamine in the jejunum, and production of cytokines secreted by OVA-specific CD4+ T cells purified from mesenteric lymph nodes, were analyzed.

RESULTS

Egg white diet-fed OVA23-3 mice developed weight loss and inflammation with villous atrophy and goblet cell hyperplasia, especially in the jejunum. A further characteristic feature was evidence of weight recovery and tissue repair. Jejunal inflammation was also observed in egg white diet-fed recombination activating gene (RAG)-2-deficient OVA23-3 mice. In addition, tissue sections revealed significant infiltration of specific IgE-positive cells and IgE-positive degranulating mast cells. Higher levels of IL-4 and significant levels of histamine were detected in the tissues. In the supernatant of OVA-stimulated T cells, IL-10 levels were also markedly elevated.

CONCLUSION

We report that high-dose and continuous intake of primitive OVA alone induces enteropathy containing regions under repair in OVA23-3 mice. Antigen-specific T cells and inflammatory cells primed by T(H)2 responses play important roles in regulation of development and improvement of the disease.

CLINICAL IMPLICATIONS

Long-term antigen intake causes T(H)2-dependent and food-sensitive enteropathy followed by tissue repair.

Cow milk is not responsible for most gastrointestinal immune-like syndromes--evidence from a population-based study

BACKGROUND

Gastrointestinal hypersensitivity to cow milk (CM) may be more common among school-aged children and young adults than previously thought.

OBJECTIVE

The objective was to study various gastrointestinal complaints and the immunologic mechanisms associated with food-related, especially CM-related, gastrointestinal disorders in young adults.

DESIGN

Of 827 subjects aged 16-21 y who completed a questionnaire on food-related gastrointestinal symptoms, 49 symptomatic subjects agreed to a clinical examination, including an interview, blood tests, a lactose-maldigestion test, a blinded CM challenge and, in severely symptomatic subjects (n = 12), an endoscopic examination. Twenty-nine subjects served as controls.

RESULTS

Approximately 10% of the subjects reported having major gastrointestinal symptoms, mainly food-related (n = 70 of 86), during the preceding year. Specific organic disease was found in 2 symptomatic subjects: 1 case of celiac disease and 1 of colitis. The result of the lactose-maldigestion test was positive in 16 of the remaining 47 symptomatic subjects, but only 4 carried the C/C(-13910) genotype for adult-type hypolactasia. The symptomatic subjects had restricted their consumption of certain foods, particularly CM. However, in a blinded challenge, CM-induced symptoms were rare. The symptomatic subjects had higher plasma soluble intercellular adhesion molecule 1 (P = 0.007) and lower granzyme A (P = 0.001) concentrations than did the control subjects. Duodenal biopsy samples tended to have higher intraepithelial CD3(+) cell counts (P = 0.065) and a higher expression of transforming growth factor beta (P = 0.073) and interleukin 12p35 messenger RNA (P = 0.075) than did the control subjects.

CONCLUSIONS

In an unselected cohort of young adults, 8% reported food-related gastrointestinal symptoms. The finding of immunologic activity implied the existence of a food-related gastrointestinal syndrome but not one induced by CM.

Increased IFN-gamma secretion from duodenal biopsy samples in delayed-type cow's milk allergy

A delayed and local gastrointestinal hypersensitivity to cow's milk (CM) protein is difficult to diagnose and there are limited data on this disorder. The aim of this study was to investigate local intestinal cytokine secretion in the upper small intestine in children with delayed-type cow's milk allergy (CMA). Duodenal biopsy samples from 31 children with delayed CMA, 14 with celiac disease (CD), and 14 healthy controls were studied for the spontaneous release of IFN-gamma, TNF-alpha, IL-2, IL-4, IL-5, and IL-10, measured by cytometric bead array, and of TGF-beta and IL-6 measured by ELISA. The children with delayed CMA secreted more IFN-gamma than the controls (p = 0.006) and the children with CD (p = 0.006). The children with CD secreted more IL-6 compared to the controls (p = 0.008) and the children with delayed CMA (p = 0.002). The children with delayed CMA who had continuously been exposed to CM secreted less TGF-beta than the children with delayed CMA who avoided CM (p = 0.050), and showed a tendency towards lower secretion compared to the controls (p = 0.078). Secretions of TNF-alpha, IL-2, IL-4, IL-5, and IL-10 were low in general; however, the children with delayed CMA who did not avoid CM secreted more IL-4 and IL-10 than the controls (p = 0.016, 0.059). In conclusion, the children with delayed CMA showed up-regulation of IFN-gamma. Interestingly, TGF-beta secretion was up-regulated in those children with delayed CMA who avoided CM suggesting recovery of regulation mechanisms.

Determination of the T cell epitopes of the lipocalin allergen, Rat n 1

BACKGROUND

Laboratory animal allergy (LAA) is an important cause of occupational sensitization and asthma. Rats are a frequent cause of LAA and the major rat allergen, Rat n 1, is a member of the lipocalin protein family, which includes several other animal allergens such as the cow allergen, Bos d 2. To date, Bos d 2 is the only mammalian lipocalin allergen to have been studied in detail.

OBJECTIVE

We undertook a cross-sectional study of a large population of individuals exposed to laboratory rats to determine the proliferative responses of peripheral blood mononuclear cells (PBMCs) to the major rat allergen, Rat n 1.

METHODS

Eighty-three cases (defined by a positive skin prick test (SPT) > or =3 mm and/or a positive RAST > or =2% binding) and 274 referents without specific IgE to rats were tested for their proliferative responses of PBMCs to rat allergen. Cytokine release to rat urinary protein was examined in 28 sensitized and 42 non-sensitized exposed individuals.

RESULTS

Proliferation to rat urinary protein was weak in all individuals. Four regions within Rat n 1 were identified as containing potential immunodominant T cell epitopes and three of these co-localized within the conserved regions of the lipocalin molecule. All four regions within Rat n 1 overlapped considerably with the characterized epitopes of the lipocalin allergen, Bos d 2. IL-5 and ratios of IL-5/IFN-gamma were significantly increased in cases.

CONCLUSION

The response to Rat n 1 is remarkably similar to the cow lipocalin allergen Bos d 2. T cell epitopes within lipocalins appear to co-localize with the conserved regions of the molecule. LAA is characterized by an increased production of IL-5. Investigation of other lipocalin allergens will provide further information about the allergenicity of this group of proteins.

Cow's milk allergy in infants with atopic eczema is associated with aberrant production of interleukin-4 during oral cow's milk challenge

OBJECTIVES

A failure in the establishment and maintenance of oral tolerance in infancy may result in food allergy. To further assess the role of the intestinal immune system in cow's milk allergy (CMA), we investigated the systemic production of the pro-allergenic Th2 cytokine interleukin (IL)-4 and anti-allergenic cytokines IL-10, transforming growth factor (TGF)-beta1 and TGF-beta2 in infants suffering from atopic eczema with and without CMA during antigen elimination diet and oral antigen exposure.

METHODS

18 infants (mean age, 9.6 months; 95% confidence interval 8.1-11.1 months) with atopic eczema and CMA and 17 infants (mean age, 9.7 months; 95% confidence interval 8.6-10.9 months) with atopic eczema tolerant to milk as assessed by a double blind, placebo-controlled cow's milk challenge were investigated. Peripheral blood mononuclear cells were obtained during antigen elimination diet and during oral cow's milk challenge and stimulated with Concanavalin-A or cow's milk or were left unstimulated. The cytokine concentrations were measured by enzyme-linked immunosorbent assay.

RESULTS

During antigen elimination, the Concanavalin A-stimulated production of TGF-beta2 was significantly lower in infants with CMA as compared with infants without CMA: 129 pg/mL (interquartile ratio, 124-144 pg/mL) vs. 149 pg/mL (interquartile ratio, 133-169 pg/mL); P = 0.016. During oral antigen exposure, the immune responses in infants with CMA were characterized by significantly higher spontaneous production of IL-4 as compared with those without CMA: 12.0 pg/mL (interquartile ratio, 5.2-28.3 pg/mL) vs. 4.2 pg/mL (interquartile ratio, 1.5-7.6 pg/mL); P = 0.018.

CONCLUSIONS

Infants with atopic eczema and CMA exhibit markedly increased systemic pro-allergenic IL-4 responses on intestinal antigen contact, which may partially be explained by a defective ability to launch anti-allergenic TGF-beta2 responses.

Donor non-specific IFN-gamma production by primed alloreactive cells as a potential screening test to predict the alloimmune response

In order to devise an in vitro experimental system that predicts the in vivo generation of T lymphocytes capable of initiating the rejection process and thereby to individualize the immunosuppressive strategy in a rational way, we studied the in vitro strength of alloresponses to non-specific donors as a surrogate tool to identify patients with heightened alloimmunity. We measured interferon gamma (IFN-gamma) produced by primed alloactivated peripheral blood lymphocytes (p-allo-PBL) against third party stimulator PBLs in four groups by the enzyme linked immunospot (Elispot) assay: 16 with excellent renal transplant function (group 1); nine with chronic rejection (group 2); 11 allo-sensitized (PRA>60%) by graft loss on dialysis (group 3) and 36 normal controls (group 4). The Elispot assay was performed using 10(6) irradiated stimulator PBLs and 10(5) responder PBLs for 24 and 48 h. Each responder was challenged by 2-4 independent stimulators.

RESULTS

At 24 h, mean+/-S.D. and 95% confidence intervals (CI) of spots/10(5) responder cells were 12.8+/-8.7 (10-15.5); 57.8+/-116 (11.9-103.7); 77.5+/-91.3 (39.8-115.2); and 20.7+/-17.9 (17.4-24.1) in groups 1-4, respectively. P<0.01 between groups 1 or 4 vs. 2 or 3. An arbitrary spot level of >or=30 has positive and negative predictive values of 58% and 95%, respectively, sensitivity of 94% and specificity of 65% to identify patients with enhanced immunity.

CONCLUSION

Chronic allogeneic stimulation is associated with enhanced p-allo-PBL. IFN-gamma producing frequencies against third party stimulators. Significant variation in IFN-gamma spots produced by p-allo-PBL may be useful to choose less allogeneic donors. Diminished p-allo-PBL alloresponse to third party stimulators may predict transplant patients with decreased alloresponses who may benefit from lesser immunosuppressive drugs.

Mixed antibody and T cell responses to peanut and the peanut allergens Ara h 1, Ara h 2, Ara h 3 and Ara h 6 in an oral sensitization model

BACKGROUND

Peanut allergy is known for its severity and persistence through life. Several peanut proteins have been identified as allergenic and are indicated as Ara h 1-7. Very little is known about the mechanisms that underlie sensitization to peanut proteins.

OBJECTIVE

The purpose of the present study was to reveal the immune responses that are induced against peanut and the peanut allergens Ara h 1, Ara h 2, Ara h 3 and Ara h 6 during sensitization, including the very early responses.

METHODS

Humoral and T cell responses against peanut and the peanut allergens were examined in an early and later stage of sensitization in an established murine model of peanut anaphylaxis. Therefore C3H/HeJ mice were orally exposed to two different doses of peanut extract plus cholera toxin.

RESULTS

Oral sensitization to peanut was characterized by an antigen-induced mixed cytokine response in the spleen (IL-4, IL-5, IL-10 and IFN-gamma), which could already be observed 7 days after the onset of exposure. Additionally, polyisotypic humoral responses (IgE, IgG1 and IgG2a) against peanut were found in the serum. Moreover, we demonstrated that these T helper (Th)1/Th2 cytokine and antibody responses were also directed specifically against the major peanut allergens Ara h 1, Ara h 2, Ara h 3 and Ara h 6.

CONCLUSIONS

This study implicates that both Th1 and Th2 phenomena are involved in the development of peanut allergy in the C3H/HeJ murine model. Furthermore, we show that the present oral model is suitable to examine immune responses to food allergens during different stages of sensitization upon treatment with a whole food extract.

Recurrent abdominal pain in school children revisited: fitting adverse food reactions into the puzzle

The diagnostic work-up of children seeking health care because of recurrent abdominal pain is a clinical challenge. Food hypersensitivity might be one of the aetiologies behind this symptom. Neither the understanding of possible immune mechanisms nor endoscopic or histological findings have yet contributed to reliable diagnostic tests.

CONCLUSION

The possibility of adverse food reactions should be evaluated among other abnormalities behind recurrent abdominal pain in children. Still, the diagnosis of immunemediated food reactions depends on open or blinded food challenge.

Spontaneous T(H)1 cytokine production by intraepithelial but not circulating T cells in infants with or without food allergies

BACKGROUND

It has been established that the maintenance of immunological tolerance to dietary antigen and the intestinal flora (oral tolerance) is an actively-maintained process dependent upon mucosal lymphocyte populations. Early life exposures appear critical in the development of such tolerance. However little is known about the activation status of mucosal lymphocytes in human infancy and childhood.

PATIENTS AND METHODS

We have performed flow cytometric analysis for cell lineage and cytokine-production status in peripheral blood and duodenal intraepithelial lymphocytes taken during endoscopy from 20 children [median age 2.9 +/- 0.6 years (median +/- SE)] in whom investigation found no intestinal abnormalities (histologically normal controls) and 30 children (median age 1.6 +/- 0.4 years) with confirmed allergy to cow's milk and other dietary antigens.

RESULTS

Regardless of clinical status, spontaneous production of cytokines was low or undetectable in peripheral blood cells. By contrast, intraepithelial CD4 and CD8 cells isolated from the small intestine were often activated, with 5% or more showing spontaneous production of T(H)1 type [interleukin-2, interferon (IFN)-gamma] cytokines in both normal controls and food-allergic children. Stimulation in vitro strongly induced cytokine production in peripheral blood but not intraepithelial lymphocytes. Immunohistochemistry showed similar density of IFN-gamma(+) intraepithelial lymphocytes in controls and allergic children.

CONCLUSIONS

Duodenal intraepithelial lymphocytes in human infants show a state of increased spontaneous activation compared with peripheral blood lymphocytes, and show no significant impairment of T(H)1 responses in food allergic children.

Cytokines and adhesion molecules in duodenal mucosa of children with delayed-type food allergy

OBJECTIVES

The aim was to investigate the expression of cytokines, adhesion molecules, and activation and proliferation markers in duodenal biopsies from children with delayed-type food allergy (FA).

METHODS

Seven children with untreated FA (uFA), seven children with treated FA (tFA) to cow milk and/or cereals, and five normal controls furnished duodenal biopsy specimens. Additionally, five pediatric patients with celiac disease were included, serving exclusively as positive controls for in situ hybridization. Interferon-gamma (IFN-gamma), interleukin-4 (IL-4), adhesion molecules, and activation markers were detected by immunohistochemistry, and expression of IFN-gamma and IL-4 messenger RNA was revealed by in situ hybridization.

RESULTS

uFA patients had a higher density of IFN-gamma positive cells in the lamina propria than did tFA patients and controls (P = 0.053 and P = 0.018). Moreover, the uFA patients exhibited a higher proportion of crypt cells in mitosis than did tFA patients (P = 0.026), and stronger staining of HLA-DR in the crypts and increased density of gammadelta-T cell receptor-positive intraepithelial lymphocytes than did controls (P = 0.048 and P = 0.010). The densities of alpha(4)beta(7) positive cells in the lamina propria tended to be higher in controls than in uFA or tFA patients (P = 0.106, P = 0.073). Expression of IL-4 mRNA was significantly higher in celiac patients than in the other study groups (uFA P = 0.006, tFA P = 0.010; controls P = 0.029), and celiac patients showed higher expression of IFN-gamma mRNA than did tFA patients or controls (P = 0.017 and P = 0.016).

CONCLUSIONS

As expected, Th1 dominance was present in the lamina propria of children with delayed-type FA. It may cause activation of epithelial cells and increase their turnover.

The mucosal immune system

This article outlines the lymphoid structures and cell types important in the intestinal immune response. Particular attention is paid to differences between rodents and man where there appears to be fundamental differences in the sources of the T and B cells which populate the mucosa. The majority of the data still suggest that Peyer's patches are the inductive site of mucosal immunity and the mucosa (lamina propria and epithelium) is the effector site, but there is growing realization that mucosal immune responses can occur in the absence of Peyer's patches and that antigen sampling may also occur in the lamina propria.

Cytokine production by cord blood mononuclear cells stimulated with cows milk proteins in vitro: interleukin-4 and transforming growth factor beta-secreting cells detected in the CD45RO T cell population in children of atopic mothers

BACKGROUND

Food antigens from the maternal circulation may sensitize fetal T cells in utero and be an important determinant in the development of food allergy.

METHODS

Here we have examined the spontaneous and recall response to cow's milk proteins of cord blood mononuclear cells (CBMC) of newborn children, using single cell ELISPOT assays.

RESULTS

In term newborns, confirming previous studies, the spontaneous cytokine response of CBMC is dominated by IL-4, IL-5, IL-10, and as shown here for the first time, TGF-beta. For TGF-beta only, the response of samples from infants of atopic mothers was significantly lower than samples from infants of non-atopic mothers. In vitro stimulation of CBMC with bovine serum albumin, casein and beta-lactoglobulin resulted in a significant increase of all cytokine-secreting cells, again dominated by T helper type 2 (Th2) cytokines. There was a clear tendency for samples from infants of atopic mothers to have lower Th2 responses than samples from infants of non-atopic mothers, which was particularly significant for both IL-4 and TGF-beta. Spontaneous cytokine secreting cells were virtually absent in cord blood from infants < 34 weeks gestation, as were cows milk protein-induced responses, although they were readily detectable in samples from infants aged > 34 weeks. To explore whether the cytokine secreting cells were in the naive CD4+ CD45RA population or memory CD4+ CD45RO T cells, these subsets were purified by positive and negative selection and tested for spontaneous and cows milk protein-induced cytokine responses. Strikingly, although the responses were small, the CD45RO+ cells from children of atopic mothers showed significant spontaneous and antigen-specific IL-4 and TGF-beta responses, whereas the same population from infants of non-atopic mothers showed virtually no response. In addition CD45RA+ cells from infants of mothers with maternal atopy showed decreased IL-4 and TGF-beta responses, especially the latter.

CONCLUSIONS

The cows milk antigen-specific IL-4 and TGF-beta responses preferentially seen in the memory cell subset of infants with a maternal history of atopy strongly suggests Th2 skewing to dietary antigens in utero.

Activated STAT4 and a functional role for IL-12 in human Peyer's patches

T cells in the Peyer's patches (PP) of the human ileum are exposed to a myriad of dietary and bacterial Ags from the gut lumen. Recall proliferative responses to common dietary Ags are readily demonstrable by PP T cells from healthy individuals, and the cytokine response is dominated by IFN-gamma. Consistent with Th1 skewing, PP cells spontaneously secrete IL-12p70, and IL-12p40 protein can be visualized underneath the PP dome epithelium. In this study, we have analyzed IL-12 signaling in PP and investigated whether IL-12 plays a functional role. CD3+ T lymphocytes isolated from PP and adjacent ileal mucosa spontaneously secrete IFN-gamma with negligible IL-4 or IL-5. RNA transcripts for IL-12Rbeta2, the signaling component of the IL-12R, are present in purified CD4+ and CD8+ T PP lymphocytes. Active STAT4, a transcription factor essential for IL-12-mediated Th1 differentiation, is readily detectable in biopsies from PP and ileal mucosa and STAT4-DNA binding activity is demonstrable by EMSA. Nuclear proteins from CD3+ T PP lymphocytes contain STAT4 and T-bet, a transcription factor selectively expressed in Th1 cells. Stimulation of freshly isolated PP cells with staphylococcal enterotoxin B dramatically enhanced the production of IFN-gamma, an effect which was largely inhibited by neutralizing anti-IL-12 Ab. These data show that IL-12 in human PP is likely to be responsible for the Th1-dominated cytokine response of the human mucosal immune system.

Paradoxical coexpression of proinflammatory and down-regulatory cytokines in intestinal T cells in childhood celiac disease

BACKGROUND & AIMS

Specific T-lymphocyte reactions are central in the pathogenesis of celiac disease, an inflammatory small-bowel enteropathy caused by a permanent intolerance to gluten. To delineate local T-lymphocyte responses to gluten, the cytokine expression in jejunal T lymphocytes of pediatric celiac patients with active disease, i.e., untreated and gluten-challenged celiac patients, was determined and compared with that of treated, symptom-free celiac patients and controls.

METHODS

Biopsy samples were collected from celiac patients and controls. Intraepithelial and lamina propria T lymphocytes were isolated separately, and the cytokine messenger RNA levels were determined by using quantitative real-time reverse-transcription polymerase chain reaction. Interferon (IFN)-gamma and interleukin (IL)-10 were determined at the protein level by immunohistochemistry.

RESULTS

Active celiac disease was characterized by distortions in cytokine expression by T lymphocytes, with highly significant increases of IFN-gamma and IL-10 but no concomitant increases in tumor necrosis factor alpha, transforming growth factor beta1, or IL-2 and no induction of IL-4. A marked shift of IFN-gamma and IL-10 production from the lamina propria to the epithelium was characteristic of active celiac disease, and as many as one fourth of the intraepithelial lymphocytes expressed IFN-gamma. Intraepithelial T lymphocytes in treated, symptom-free celiac patients still had increased IFN-gamma levels compared with controls.

CONCLUSIONS

In celiac patients, gluten intake seems to cause an overreaction in intraepithelial T lymphocytes, with uncontrolled production of IFN-gamma and IL-10. This may cause both recruitment of intraepithelial lymphocytes and a leaky epithelium, leading to a vicious circle with amplified immune activity and establishment of intestinal lesions.

Current understanding of gastrointestinal immunoregulation and its relation to food allergy

Tolerance to food antigens induced via the gut ("oral tolerance") appears to be a rather robust adaptive immune mechanism. However, the neonatal period is particularly critical in terms of mucosal defense, with regard to infections and priming for allergic disease. This is so because the intestinal barrier function provided by secretory antibodies, as well as the immunoregulatory network, is poorly developed for a variable period after birth. Notably, the postnatal development of mucosal immune homeostasis depends on the establishment of a normal commensal microbial flora and also on adequate timing and dose of dietary antigens when first introduced. In this context, breastfeeding appears to exert both shielding and positive regulatory effects. Altogether, the intestinal immune system normally seems rather fit for tolerance induction against innocuous antigens because most children with food allergy "outgrow" their problems, whereas airway allergy tends to persist.

Local allergic reaction in food-hypersensitive adults despite a lack of systemic food-specific IgE

BACKGROUND

Objective tools are lacking for the diagnosis of local gastrointestinal inflammatory reactions in skin prick test (SPT)-negative and serum IgE antibody (s-IgE Ab)-negative patients with suspected food allergy.

OBJECTIVE

The purpose of this investigation was to evaluate the presence of eosinophils, T cells, local IgE-bearing cells, IL-4, and IFN-gamma in small intestinal biopsy specimens from adult SPT-negative/s-IgE Ab-negative patients with food allergy during symptomatic and nonsymptomatic periods.

METHODS

Fourteen patients with food allergy-related gastrointestinal symptoms confirmed by double-blinded, placebo-controlled food challenge (DBPCFC) were investigated. Eleven of the patients were SPT-negative and s-IgE Ab-negative. Sex- and age-matched healthy volunteers were used as controls. Duodenal biopsies were studied with immunostaining through use of a panel of mouse monoclonal antibodies specific for eosinophils, CD3, CD4, CD8, IgE, IL-4, and IFN-gamma.

RESULTS

Significant increases in numbers of MBP+ eosinophils, IgE-bearing cells, and T cells were found in the duodenal mucosa of the patients when they were symptomatic in comparison with when they were asymptomatic and in comparison with healthy controls. Numbers of IL-4+ cells were increased and numbers of IFN-gamma+ cells were reduced in the patients when they were symptomatic in comparison with when they were asymptomatic and in comparison with the controls. There were no differences in total s-IgE levels between any of the groups.

CONCLUSION

A significant correlation was found between the appearance of symptoms of food hypersensitivity and the duodenal presence of IgE-bearing cells, activated eosinophils, and T cells in patients with negative SPT results and negative s-IgE Ab to the offending food. We suggest that a localized IgE-mediated response caused the gastrointestinal symptoms seen in these patients.

Nature and function of gastrointestinal antigen-presenting cells

Antigen-presenting cells (APCs) of the human gut are heterogeneous, including both macrophages, a variety of dendritic cells and B cells. They are found both in gut-associated lymphoid tissue and in the mucosal lamina propria, especially beneath the surface epithelium. APCs have diverse phenotypes and therefore probably different functions in various locations; their expression levels of a variety of costimulatory molecules are most likely important for immunological decision making of stimulated T cells, either locally in the gut or in regional lymph nodes to which migrating APCs (dendritic cells) carry antigen. Thus, APCs are involved in active immunity as well as in induction of oral tolerance. However, their precise role in food allergy remains to be defined.

Enhanced transepithelial antigen transport in intestine of allergic mice is mediated by IgE/CD23 and regulated by interleukin-4

BACKGROUND & AIMS

We previously described a system for enhanced transepithelial transport of antigen in which both the amount of specific antigen and its rate of transport were dramatically increased in intestine of sensitized rats compared with controls. This study investigated the essential components mediating antigen uptake in mice genetically deficient for interleukin (IL)-4 or CD23.

METHODS

Mice were actively or passively sensitized to horseradish peroxidase (HRP). Jejunal segments from control or sensitized mice were mounted in Ussing chambers and challenged with HRP from the luminal side. Tissues were processed for electron microscopy, and photomicrographs were analyzed for antigen uptake (location and area of HRP-containing endosomes). Immunohistochemistry and reverse-transcription polymerase chain reaction were used to detect epithelial CD23 expression.

RESULTS

Actively sensitized IL-4(+/+), but not IL-4(-/-) mice, displayed increased transepithelial antigen transport and CD23 expression on enterocytes. Passively sensitized IL-4(+/+) and IL-4(-/-) mice displayed elevated antigen transport after transfer of immune serum but not if the serum was depleted of immunoglobulin (Ig) E or IL-4. IL-4 added to cultured IEC-4 cells up-regulated expression of CD23 messenger RNA. The augmented antigen uptake was inhibited by anti-CD23 and was absent in sensitized CD23(-/-) mice.

CONCLUSIONS

Our studies indicate that IL-4 regulates IgE/CD23-mediated enhanced transepithelial antigen transport in sensitized mouse intestine.

Identification of beta-lactoglobulin-derived peptides and class II HLA molecules recognized by T cells from patients with milk allergy

BACKGROUND

Cow's milk allergy impairs the health and development of many infants since it deprives them of adequate nutrition. Cow's milk fractions contain many allergens, and beta-lactoglobulin (BLG) is one of the major allergens.

OBJECTIVE

The purpose of this study was to determine T cell epitopes, antigen-presenting molecules and cytokine production by T cells in relation to BLG. The results can provide new therapeutic possibilities of using analogue peptides of BLG for infants with cow's milk allergy.

METHODS

Using a mixture of a panel of overlapping synthetic peptides that cover the entire BLG molecule, we established polyclonal BLG-specific short-term T cell lines and clones from peripheral blood mononuclear cells of four patients with allergy to cow's milk carrying most of the common human leucocyte antigen (HLA) haplotypes seen in the Japanese population. We then identified the T cell epitopes and antigen-presenting molecules, and measured the production of cytokines interleukin (IL)-4, IL-5 and interferon-gamma in the culture supernatants.

RESULTS

The T cell lines established from the four patients responded to seven different peptides. Three of the peptides stimulated the T cells of two donors, regardless of the HLA types. The patterns of inhibition of the proliferative responses of the cell lines by anti-HLA class II antibodies were heterogeneous; three were mainly inhibited by anti-HLA-DR mAbs, and the other was inhibited by anti-HLA-DQ mAbs. High levels of IL-5 were produced by these T cell lines.

CONCLUSIONS

Patients' T cells recognized BLG in association with a variety of HLA-DR or -DQ as antigen-presenting molecules. Although some peptides did have a more potent T cell stimulatory activity than others, the T cell receptor ligands formed with the BLG molecule are heterogeneous. Peptides for the desensitization of T cells of the patients with cow's milk allergy need to be designed keeping in mind the different requirements in different ethnic groups.

Production of MDC/CCL22 by human intestinal epithelial cells

The intestinal mucosa contains a subset of lymphocytes that produce Th2 cytokines, yet the signals responsible for the recruitment of these cells are poorly understood. Macrophage-derived chemokine (MDC/CCL22) is a recently described CC chemokine known to chemoattract the Th2 cytokine producing cells that express the receptor CCR4. The studies herein demonstrate the constitutive production of MDC/CCL22 in vivo by human colon epithelium and by epithelium of human intestinal xenografts. MDC/CCL22 mRNA expression and protein secretion was upregulated in colon epithelial cell lines in response to proinflammatory cytokines or infection with enteroinvasive bacteria. Inhibition of nuclear factor (NF)-kappaB activation abolished MDC/CCL22 expression in response to proinflammatory stimuli, demonstrating that MDC/CCL22 is a NF-kappaB target gene. In addition, tumor necrosis factor-alpha-induced MDC/CCL22 secretion was differentially modulated by Th1 and Th2 cytokines. Supernatants from the basal, but not apical, side of polarized epithelial cells induced a MDC/CCL22-dependent chemotaxis of CCR4-positive T cells. These studies demonstrate the constitutive and regulated production by intestinal epithelial cells of a chemokine known to function in the trafficking of T cells that produce anti-inflammatory cytokines.

IL-12 and Th1 immune responses in human Peyer's patches

Oral tolerance is a well-characterized phenomenon in animals and is highly effective when induced as a treatment for experimental autoimmune disease. However, its use as a therapeutic modality for the treatment of autoimmune disease in humans has been disappointing. Much of the rationale for its use in humans is based on the finding that feeding antigen to rodents elicits regulatory T cells in Peyer's patches (PPs) that secrete immunosuppressive cytokines such as transforming growth factor (TGF)-beta. By contrast, human antigen-specific PP T-cell responses, and mucosal T-cell responses in general, are strongly biased towards T helper 1 (Th1) cells, which are pro-inflammatory rather than immunosuppressive. This is caused by the high local levels of interleukin (IL)-12 in PPs.

Dietary gangliosides positively modulate the percentages of Th1 and Th2 lymphocyte subsets in small intestine of mice at weaning

We studied the influence of dietary gangliosides on the number of spontaneous cytokine-secreting cells from two intestinal lymphocyte populations: lamina propria lymphocytes and Peyer's patches lymphocytes in Balb/c mice for 28 days after weaning. Weanling mice were separated into two groups, designated as Control and BG. The Control group was fed with a semipurified diet without gangliosides and the BG group was fed with the semipurified diet supplemented with 47 mg/kg of a mixture of bovine brain gangliosides. Intestinal lymphocytes were isolated from mice killed at 3, 7, 14 and 28 days after weaning, and the percentages of spontaneous Th1 as well as Th2 cytokine-secreting lymphocytes were determined using the ELISPOT assay. The BG group animals showed an earlier development in the number of cytokine-secreting cells, which appeared one week later in Control animals. In addition, mice fed with the ganglioside-supplemented diet showed a significantly higher number of Th1 and Th2 cytokine-secreting lymphocytes than Control mice in lamina propria and Peyer's patches lymphocytes at the end of the experimental period (28 days). Our results suggest that dietary gangliosides influence the maturation process of the intestinal immune system that take place during weaning.

Human Peyer's patch T cells are sensitized to dietary antigen and display a Th cell type 1 cytokine profile

Animal studies have demonstrated that feeding Ags induces regulatory (Th2, Th3) cells in Peyer's patches (PP), which migrate to the periphery and produce immunomodulatory cytokines such as IL-4, IL-10, or TGF-beta. In this work we have attempted to extend this paradigm to man by analyzing the response of human PP T cells to in vitro challenge with the common dietary Ag beta-lactoglobulin (betalg) of cow's milk. PP T cells stimulated with betalg showed enhanced proliferation compared with blood T cells from the same patient. Increased expression of CD25 and the Th1-associated chemokine receptor CCR5 was also seen on CD4(+) and CD8(+) PP T cells, but not blood T cells, stimulated with betalg. By enzyme-linked immunospot assay and RT-PCR, the PP T cell recall response to betalg and casein was dominated by IFN-gamma, with negligible IL-4, IL-5, IL-10, or TGF-beta. To help explain the PP T cell response to betalg, we examined IL-12 expression. Both IL-12p40 and -p35 transcripts were abundantly expressed in PP, but not in adjacent normal ileal mucosa. Immunoreactive IL-12p40-containing cells were present below the PP dome epithelium. Furthermore, in culture, PP, but not paired PBMC, spontaneously released IL-12p70. These results suggest that the human response to oral Ags in the gut may be different from that in rodents.

Enhanced intestinal transepithelial antigen transport in allergic rats is mediated by IgE and CD23 (FcepsilonRII)

We previously reported that active sensitization of rats resulted in the appearance of a unique system for rapid and specific antigen uptake across intestinal epithelial cells. The current studies used rats sensitized to horseradish peroxidase (HRP) to define the essential components of this antigen transport system. Sensitization of rats to HRP stimulated increased HRP uptake into enterocytes (significantly larger area of HRP-containing endosomes) and more rapid transcellular transport compared with rats sensitized to an irrelevant protein or naive control rats. Whole serum but not IgE-depleted serum from sensitized rats was able to transfer the enhanced antigen transport phenomenon. Immunohistochemistry demonstrated that sensitization induced expression of CD23, the low-affinity IgE receptor (FcepsilonRII), on epithelial cells. The number of immunogold-labeled CD23 receptors on the enterocyte microvillous membrane was significantly increased in sensitized rats and was subsequently reduced after antigen challenge when CD23 and HRP were localized within the same endosomes. Finally, pretreatment of tissues with luminally added anti-CD23 antibody significantly inhibited both antigen transport and the hypersensitivity reaction. Our results provide evidence that IgE antibodies bound to low-affinity receptors on epithelial cells are responsible for the specific and rapid nature of this novel antigen transport system.

Expression of and responses to CD2 and CD3 in 18-month-old children with and without atopic dermatitis

We hypothesize that atopy is associated with a reduced T-cell function early in life and an imbalance in cytokine production. The purpose of this study was to investigate the expression of and responses to CD2 and CD3 in children who did or did not develop atopic dermatitis early in life. The expression of CD2 and CD3 was analyzed by flow cytometry, and proliferation of CD2 and CD3 was studied by 3H-thymidine incorporation in phytohaemagglutinin (PHA)- and anti-CD3-stimulated peripheral blood mononuclear cells (PBMC) of 18-month-old children, 25 with and 29 without atopic dermatitis. Exogenous interleukin (IL)-2 was added to compensate for possible functional differences in accessory cells. Anti-CD3-induced secretion of IL-4, IL-5, IL-6, IL-10, IL-13, and interferon-gamma (IFN-gamma) was analyzed by enzyme-linked immunosorbent assay (ELISA). Atopy was associated with a low proportion of CD2+ lymphocytes. Responsiveness to PHA, which activates lymphocytes partly via the sheep erythrocyte receptor, CD2, was reduced in the allergic children. The anti-CD3-induced proliferation declined more rapidly with antibody dilution in the allergic than in the non-allergic children. Atopic dermatitis was associated with high levels of anti-CD3-stimulated IL-5 secretion. The IL-4/IL-10 and IL-4/ITFN-gamma ratios were higher in children with elevated total immunoglobulin E (IgE) levels. Skin prick test-negative children with eczema produced higher levels of IL-10 than skin prick test-positive children. In conclusion, atopic children have a reduced T-cell function. Atopic dermatitis is associated with increased IL-5 production, while high total IgE levels are associated with high IL-4/IFN-gamma and IL-4/IL-10 ratios.

Weaning induces an increase in the number of specific cytokine-secreting intestinal lymphocytes in mice

Intestinal immunity differs from systemic immunity in several aspects and is frequently studied separately. In this work we have analysed the frequency of mononuclear cells spontaneously secreting the cytokines IL-2, IL-4, IL-5, IL-6, IL-10, interferon gamma (IFN-gamma) and tumour necrosis factor (TNF-alpha), in Peyer's patches and lamina propria of small intestine in mice by enzyme linked immunosorbent spot (ELISPOT) during 1 month after weaning. We have found a high percentage of spontaneous Th(1)as well as Th(2)cytokine-secreting lymphocytes in both populations, Peyer's patches and lamina propria. An increase in the number of the lymphocytes secreting most of the studied cytokines, at 1 and 2 weeks after weaning, was also observed. These results suggest that the increase in the number of cytokine secreting lymphocytes may be one of the potential mechanisms involved in the development of the intestinal immune system at weaning.