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

Late onset reactions to oral food challenge are linked to low serum interleukin-10 concentrations in patients with atopic dermatitis and food allergy

BACKGROUND

Aberrant cytokine production in vitro has been associated with atopic disease. No study has as yet been made of the circulating cytokine profiles in atopic patients with food allergy in response to oral allergen challenge.

OBJECTIVE

To assess the effect of oral allergen challenge on the serum cytokine concentrations in patients with atopic dermatitis and food allergy.

METHODS

Serum concentrations of interleukin (IL)-10, transforming growth factor beta 1, IL-1ra, IL-6, IL-5, IL-4 and interferon (IFN)-gamma were measured before and after double-blind, placebo-controlled food challenges (DBPCFC) (n = 73). Before DBPCFC, combined skin prick and patch testing was performed for cow milk, egg, soybean and cereals, and production of IFNgamma, IL-4, IL-10 and tumour necrosis factor alpha (TNFalpha) was determined in supernatants of cultures of peripheral blood mononuclear cells (PBMCs) stimulated by cow milk.

RESULTS

The oral food challenge triggered immediate onset exanthematous reactions in 22 cases and late onset eczematous reactions in 29. The late-reacting cases had more positive skin patch test and negative skin prick test reactivities with allergenic food, and they had lower serum IL10 concentrations than immediate-reacting cases. In challenge-positive cases, IL-10 concentrations increased from 2.9 (0.1-5.04) pg/mL to 3. 9 (1.2-8.3) pg/mL in response to DBPCFC, P = 0.05, median (interquartile ranges), but not in those tolerant to cow milk. PBMCs of patients with cow milk allergy but not of those tolerant to cow milk generated TNFalpha in response to cow milk in vitro.

CONCLUSION

These results indicate that oral allergen challenge in atopic patients with food allergy triggers systemic release of IL-10. Patients with late onset reactions were found to have lower serum IL-10 concentrations than their immediate-reacting counterparts. Considering that IL-10 is an inhibitory cytokine of delayed-type hypersensitivity, low IL-10 in late-reacting patients may explain the high frequency of their positive skin patch tests combined with negative skin prick tests.

Normal immune responses to ingested foods

This is a short review of the literature with a bias toward the author's work. Small amounts of dietary antigens are taken up into the circulation. B-cell responses to foods (antibodies and antibody-secreting cells) occur as a physiological event locally and in the circulation in all three major immunoglobulin classes. A low levels of IgE is also a normal phenomenon. IgA anti-gliadin antibodies represent an exception. Antibody titers in general tend to decline with age. T-cell responses specific for foods are low in the circulation of healthy subjects. T-cell cytokines are more frequently produced in the gastrointestinal mucosa compared with the circulation. Results indicate that the phenomenon of oral tolerance takes place in humans. Oral tolerance within the T cell system may represent an important regulatory mechanism for normal immunity.

Food-induced malabsorption syndromes

A syndrome of chronic diarrhea, vomiting, and failure to thrive was described 35 years ago. The syndrome was caused by damage in the jejunum after ingestion of cow's milk. Symptoms appeared in young infants shortly after introduction of cow's milk formula. Patients had moderate steatorrhea, decreased absorption of D-xylose, and, often, iron-deficiency anemia and hypoproteinemia. They had strong IgA and IgG antibodies to cow's milk. IgE antibodies to cow's milk were negative, as a rule. Indicators of cell-mediated immune reaction to cow's milk proteins were often positive. Patients were tolerant to cow's milk by the age of 3 years. Malabsorption was due to damage to the jejunal mucosa: Varying villus atrophy was associated with inflammation in surface epithelium and lamina propria. The epithelial cell renewal rate increased. Surface epithelial cells decreased in height, with short, furry microvilli and large aggregates of lysozymes. The number of intraepithelial lymphocytes was markedly increased, but normalized during cow's milk elimination. Most of these lymphocytes had alpha/beta T-cell receptors, and many were cytotoxic. Some specimens had an increase in gamma/delta T-cell receptor-bearing cells. In the lamina propria, CD4+ cells predominated, and some of them were activated. IgA- and IgM-containing cells were markedly increased during cow's milk exposure, but IgE cells were not abnormal. The density of eosinophils was moderately increased. Secretion of interferon-gamma by cells isolated from patients' intestines was markedly increased. Morphologic and immunologic findings suggest that T-cell-mediated reaction to proteins in cow's milk is present in the small intestines of patients with this syndrome and causes this enteropathy.

Different serum interleukin-12 and sCD30 levels in food- and pollen-sensitized children

It has been proposed that a down-regulation of interleukin (IL)-12 and interferon (IFN)-gamma might be related to susceptibility to allergy in early life. The aim of this study was to assess serum IL-12 levels in food-sensitized and pollen-sensitized children and to compare these with another activation marker, sCD30. Twenty children with pollen allergy and 22 food-sensitized children were included. The diagnosis of immunoglobulin (Ig)-E-mediated allergy, suggested by clinical symptoms, was based on skin-prick tests, serum IgE antibodies and total IgE levels. Samples from 24 non-allergic children were used as controls. IL-12 and sCD30 levels were measured by ELISA. It was found that pollen-sensitized patients had normal IL-12 and higher sCD30 levels than controls (114 vs. 63 U/ml, p = 0.028), but, surprisingly, food-sensitized infants showed normal sCD30 and increased serum IL-12 levels (323 vs. 118 pg/ml, p = 0.0001). No differences were found in patients suffering from asthma or allergic dermatitis. Levels of sCD30 and IL-12 determined in May showed a strong correlation with those obtained in November. Interleukin-12 and IgE levels had an inverse correlation (r = -0.494, p = 0.0001) whereas no correlation was found between sCD30 and IgE. Age had a strong negative influence on IL-12 levels in allergic (Z = 4.834, p < 0.0005) and in normal children (Z = 3.00, p < 0.002); by contrast, sCD30 levels were not significantly age-dependent. When IL-12 levels from the food-allergy group were compared with those from normal controls younger than 4 years of age, the difference remained significant (p = 0.001), ruling out an age-bias. The conclusions made in this study were that serum IL-12 and sCD30 showed different behaviors in children with food or pollen allergy. We found IL-12 and sCD30 levels in pollen-allergic patients that agree with the classical T-helper (Th) 1/Th2 paradigm of allergy. In contrast, serum IL-12 levels were increased in food-sensitized children, suggesting a different immunologic pathogenesis.

Mucosal immunity and tolerance: relevance to vaccine development

The mucosal immune system of mammals consists of an integrated network of lymphoid cells which work in concert with innate host factors to promote host defense. Major mucosal effector immune mechanisms include secretory antibodies, largely of immunoglobulin A (IgA) isotype, cytotoxic T cells, as well as cytokines, chemokines and their receptors. Immunologic unresponsiveness (tolerance) is a key feature of the mucosal immune system, and deliberate vaccination or natural immunization by a mucosal route can effectively induce immune suppression. The diverse compartments located in the aerodigestive and genitourinary tracts and exocrine glands communicate via preferential homing of lymphocytes and antigen-presenting cells. Mucosal administration of antigens may result in the concomitant expression of secretory immunoglobulin A (S-IgA) antibody responses in various mucosal tissues and secretions, and under certain conditions, in the suppression of immune responses. Thus, developing formulations based on efficient delivery of selected antigens/tolerogens, cytokines and adjuvants may impact on the design of future vaccines and of specific immunotherapeutic approaches against diseases associated with untoward immune responses, such as autoimmune disorders, allergic reactions, and tissue-damaging inflammatory reactions triggered by persistent microorganisms.

Role for IL-4 in macromolecular transport across human intestinal epithelium

Increased epithelial permeability is associated with intestinal inflammation, but there is little information on factors that regulate barrier function in the absence of or before inflammation. We examined if interleukin (IL)-4, or serum from atopic individuals, could alter the barrier function of human colonic epithelial (T84) monolayers to antigenic-sized macromolecules. IL-4 and atopic serum significantly decreased T84 monolayer resistance and increased transepithelial horseradish peroxidase (HRP) transport. Bidirectional transport studies demonstrated that IL-4 selectively enhanced apical-to-basal movement of HRP. HRP transport induced by IL-4 was inhibited by cold (4 degrees C) and the tyrosine kinase inhibitor genistein, but not the protein kinase C inhibitor staurosporine. Electron microscopic analysis demonstrated that both transcellular and paracellular pathways were affected. Anti-IL-4 antibodies abolished the increase in HRP transport in response to both IL-4 and serum. We speculate that enhanced production of IL-4 in allergic conditions may be a predisposing factor to inflammation by allowing uptake of luminal antigens that gain access to the mucosal immune system.

The mucosal adhesion receptor alpha4beta7 integrin is selectively increased in lymphocytes stimulated with beta-lactoglobulin in children allergic to cow's milk

BACKGROUND

It has been shown in mice that the integrin alpha4beta7 directs the migration of memory T cells into the gut-associated lymphoid tissue. However, little is known about T-cell homing mechanisms in children with food allergies.

OBJECTIVE

We investigated the expression of this and other integrins in children with different manifestations of cow's milk allergy (urticaria, atopic dermatitis, and wheezing).

METHODS

PBMCs were stimulated with beta-lactoglobulin, 1 of the major allergenic proteins in cow's milk, and tetanus toxoid. Integrin expression was studied by flow cytometric analysis after 1 week of culture.

RESULTS

We found significantly higher expression of the alpha4beta7 integrin in cells from patients compared with control subjects with no allergies (P =. 005) when beta-lactoglobulin was used to stimulate the cells. alpha4beta7 integrin was also expressed at significantly higher levels in beta-lactoglobulin-stimulated cells than in tetanus toxoid-stimulated cells (P =.005). The alphaEbeta7 and the alpha4beta1 integrins were not upregulated by allergen stimulation. Most alpha4beta7 integrin-expressing cells were identified as CD4(+) T cells.

CONCLUSION

These results show that alpha4beta7 integrin expression after stimulation with beta-lactoglobulin correlates with the presumptive site of cow's milk sensitization (ie, the gut-associated lymphoid tissue but not with the site of symptoms of cow's milk allergy).

Effector and regulatory lymphoid cells and cytokines in mucosal sites

In this review, I hope to have highlighted that cytokines are of crucial importance in the normal homeostasis of the gut immune system, the interactions of the gut immune system with enteric antigens and also in tissue injury associated with IBD. There is evidence from a number of different systems that the response to nominal non-replicating antigens, administered nasally or orally, is skewed towards a non-Th1 type of response. To say that the response is Th2, Th3 or Tr is premature. IL-10 and TGF beta seem to be important in downregulating potentially tissue-damaging Th1 responses to the normal flora and possibly food antigens. However, it need to be seen whether the mouse results also apply to humans. A consistent pattern in disease states, whether it be human or mouse, is an exaggerated Th1 type response with excess local production of IFN-gamma and TNF alpha, and its association with tissue injury. An important question to address is whether this represents a switch from the Th2, Th3, or Tr pathway towards a Th1 pathway, or whether the Th1 pathway is in fact always present in the gut, but is kept in check and non-pathogenic by regulatory cells. Equally important is the need to discover where regulation occurs: is it in the PP or the lamina propria? Intriguing results from Kronenberg and colleagues have shown that SCID mice reconstituted with CD45RBhi or CD45RBlo cells show no difference in the re-population of the gut prior to disease (ARANDA et al. 1997). The reason for colitis developing in those mice reconstituted with CD45RBhi cells is therefore more complex than merely differential re-population kinetics. No matter what the outcome is, these and other related questions dealing with the induction and expression of mucosal T-cell responses are going to produce some surprises in the next few years.

T cell immunity to oral allergens

Considerable light has been thrown on the mechanisms of oral tolerance (or, more correctly, orally-induced systemic tolerance) in the past 12-18 months. While it is very clear that T cell anergy and apoptosis can occur after being fed antigen, a major pathway that has been described in different models is the induction of regulatory T cells which secrete transforming growth factor beta. These cells have been designated Th3 cells but their relation to the in-vitro-generated Tr cells, which inhibit tissue-damaging T cell responses in the gut mucosa, is not known. An important discovery is that food antigens have major systemic effects on T cells, similar in many ways to those seen following intravenous injection of soluble antigens. This conceptually moves us away from the notion that there is something special about mucosal (compared to systemic) lymphoid tissue to the notion that it is the type of antigens seen in the gut (i.e. digested, soluble polypeptides) which dictates the types of response seen there. After initial excitement, clinical trials using oral tolerance to treat autoimmune disease have been somewhat disappointing.

Gluten induces an intestinal cytokine response strongly dominated by interferon gamma in patients with celiac disease

BACKGROUND & AIMS

Celiac disease appears to be a T cell-mediated enteropathy induced by gluten in genetically predisposed individuals. Duodenal biopsy specimens from patients with celiac disease and histologically normal controls were investigated to see if cytokine expression is related to disease activity.

METHODS

Cytokine messenger RNA (mRNA) expression was determined by quantitative reverse-transcription polymerase chain reaction and in situ expression by immunohistochemistry.

RESULTS

In normal controls, mRNA levels were usually below the quantitative limit, even after in vitro gluten stimulation. By contrast, interferon (IFN)-gamma mRNA was increased more than 1000-fold in untreated disease. In vitro gluten stimulation of specimens from treated patients (gluten-free diet) increased IFN-gamma mRNA to the levels of untreated patients. In addition, increased mRNA levels for interleukin (IL)-2, IL-4, IL-6, and tumor necrosis factor alpha were found after such stimulation, whereas mRNA for IL-5, IL-10, and IL-12p40 was usually below the quantitative level. Biopsy specimens from untreated patients contained on average 10-fold more lamina propria cells positive for IFN-gamma than normal controls, whereas cells containing IL-4 were rare in both subject groups.

CONCLUSIONS

The results show that mucosal gluten exposure in patients with celiac disease rapidly elicits high levels of IFN-gamma expression and lower levels of IL-2, IL-4, IL-6, and tumor necrosis factor alpha even in the virtual absence of IL-12.