Mucosal immunity and gastrointestinal antigen processing

Application of enzyme-linked immunosorbent assay to detect antimicrobial peptides in human intestinal lumen

Intestinal transplantation is the definitive treatment for intestinal failure. However, tissue rejection and graft-versus-host disease are relatively common complications, necessitating aggressive immunosuppression that can itself pose further complications. Tracking intraluminal markers in ileal effluent from standard ileostomies may present a noninvasive and sensitive way to detect developing pathology within the intestinal graft. This would be an improvement compared to current assessments, which are limited by poor sensitivity and specificity, contributing to under or over-immunosuppression, respectively, and by the need for invasive biopsies. Herein, we report an approach to reproducibly analyze ileal fluid obtained through stoma sampling for antimicrobial peptide/protein concentrations, reasoning that these molecules may provide an assessment of intestinal homeostasis and levels of intestinal inflammation over time. Concentrations of lysozyme (LYZ), myeloperoxidase (MPO), calprotectin (S100A8/A9) and β-defensin 2 (DEFB2) were assessed using adaptations of commercially available enzyme-linked immunosorbent assays (ELISAs). The concentration of α-defensin 5 (DEFA5) was assessed using a newly developed sandwich ELISA. Our data support that with proper preparation of ileal effluent specimens, precise and replicable determination of antimicrobial peptide/protein concentrations can be achieved for each of these target molecules via ELISA. This approach may prove to be reliable as a clinically useful assessment of intestinal homeostasis over time for patients with ileostomies.

Chimonanthus nitens Oliv Polysaccharides Modulate Immunity and Gut Microbiota in Immunocompromised Mice

To investigate the immunomodulatory activities of Chimonanthus nitens Oliv polysaccharides (COP1), an immunosuppressive mouse model was generated by cyclophosphamide (CY) administration and then treated with COP1. The results demonstrated that COP1 ameliorated the body weight and immune organ (spleen and thymus) index of mice and improved the pathological changes of the spleen and ileum induced by CY. COP1 strongly stimulated the production of inflammatory cytokines (IL-10, IL-12, IL-17, IL-1β, and TNF-α) of the spleen and ileum by promoting the mRNA expressions. Furthermore, COP1 had immunomodulatory activity by increasing several transcription factors (JNK, ERK, and P38) in the mitogen-activated protein kinase (MAPK) signaling pathway. Related to the above immune stimulatory effects, COP1 positively affected the production of short-chain fatty acids (SCFAs) and the expression of ileum tight junction (TJ) protein (ZO-1, Occludin-1, and Claudin-1), upregulated the level of secretory immunoglobulin A (SIgA) in the ileum and microbiota diversity and composition, and improved intestinal barrier function. This study suggests that COP1 may provide an alternative strategy for alleviating chemotherapy-induced immunosuppression.

Temporary Deceased Donor Splenic Transplant Prior to Intestinal Transplantation: A New Strategy for Desensitization?

Intestinal transplantation is a therapeutic treatment option for patients with irreversible intestinal failure. The presence of donor-specific antibodies (DSAs) has been associated with increased antibody-mediated rejection and allograft loss for recipients of all the solid organ transplants. This case report describes the posttransplant course in the first year of a patient who received a T-cell and B-cell flow cross-match (FXM) and complement-dependent cytotoxicity cross-match positive intestinal transplant in the presence of several class I and class II DSAs who underwent a "temporary desensitization" using the donor spleen. The temporary donor splenic transplant removed several class I and II DSAs as demonstrated by the negative subsequent T-cell FXM, the decreased mean channel shift of the positive B-cell FXM with a significant decrease in DSA mean florescence intensity post temporary splenic transplant. The patient experienced an isolated incidence of acute rejection, which responded to therapy. He had no infectious or cancerous sequelae from the immunosuppression modalities. He was able to discontinue total parenteral nutrition and gained weight after the procedure. Long-term effects are not able to be determined from this approach; hence, further research is warranted to better evaluate the real efficacy of this strategy.

Differential cytokine and chemokine expression during rejection and infection following intestinal transplantation

BACKGROUND/OBJECTIVES

Rejection and infectious enteritis in intestinal transplant (ITx) patients present with virtually identical symptoms. Currently, the gold standard for differentiating between these two conditions is endoscopy, which is invasive and costly. Our primary aim was to identify differences in peripheral blood cytokines during episodes of acute cellular rejection (ACR) and infectious enteritis in patients with intestinal transplants.

METHODS

This was a prospective, cross-sectional study involving ITx patients transplanted between 2000 and 2016. We studied 63 blood samples collected from 29 ITx patients during periods of normal (n = 24) and abnormal (n = 17) allograft function. PBMCs from whole blood samples were cultured under unstimulated or stimulated conditions with phytohemagglutinin (PHA). The supernatant from these cultures were collected to measure cytokine and chemokine levels using a 38-plex luminex panel.

RESULTS

Our study found that cytokines and chemokines are differentially expressed in normal, ACR, and infectious enteritis samples under unstimulated conditions based on heatmap analysis. Although each cohort displayed distinctive signatures, only MDC (p = 0.037) was found to be significantly different between ACR and infectious enteritis. Upon stimulation of PBMCs, patients with ACR demonstrated increased immune reactivity compared to infectious enteritis; though this did not reach statistical significance.

CONCLUSIONS

To our knowledge, this is the first comprehensive study comparing cytokine expression during acute rejection and infectious enteritis in intestinal transplant recipients. Our results suggest that cytokines have the potential to be used as clinical markers for risk stratification and/or diagnosis of ACR and infectious enteritis.

Tryptophan Metabolites Along the Microbiota-Gut-Brain Axis: An Interkingdom Communication System Influencing the Gut in Health and Disease

The ‘microbiota-gut-brain axis’ plays a fundamental role in maintaining host homeostasis, and different immune, hormonal, and neuronal signals participate to this interkingdom communication system between eukaryota and prokaryota. The essential aminoacid tryptophan, as a precursor of several molecules acting at the interface between the host and the microbiota, is fundamental in the modulation of this bidirectional communication axis. In the gut, tryptophan undergoes 3 major metabolic pathways, the 5-HT, kynurenine, and AhR ligand pathways, which may be directly or indirectly controlled by the saprophytic flora. The importance of tryptophan metabolites in the modulation of the gastrointestinal tract is suggested by several preclinical and clinical studies; however, a thorough revision of the available literature has not been accomplished yet. Thus, this review attempts to cover the major aspects on the role of tryptophan metabolites in host-microbiota cross-talk underlaying regulation of gut functions in health conditions and during disease states, with particular attention to 2 major gastrointestinal diseases, such as irritable bowel syndrome (IBS) and inflammatory bowel disease (IBD), both characterized by psychiatric disorders. Research in this area opens the possibility to target tryptophan metabolism to ameliorate the knowledge on the pathogenesis of both diseases, as well as to discover new therapeutic strategies based either on conventional pharmacological approaches or on the use of pre- and probiotics to manipulate the microbial flora.

Effects of the solubility of yeast cell wall preparations on their potential prebiotic properties in dogs

Derivatives of yeast cell wall (YCW) have been studied for their potential prebiotic effects. Recently, new purified and soluble preparations have been developed in an attempt to increase their biological actions. Two YCW preparations, one conventional and another with higher solubility of the mannan oligosaccharide fraction, were evaluated on dogs. One food formulation was used, divided into the following treatments: CON-control, without yeast cell wall addition; YCW-addition of 0.3% of a conventional yeas cell wall extract; YCWs-addition of 0.3% of a yeast cell wall extract with high mannan oligosaccharide solubility. Twenty-four beagle dogs were used, eight per food, distributed on a block design. Blocks lasted 32 days, and TNF-a, IL-6, IL-10, ex vivo production of hydrogen peroxide and nitric oxide by peripheral neutrophils and monocytes, phagocytic index, and fecal IgA were evaluated at the beginning and end of each period. Additionally, nutrient digestibility, feces production and quality, and fermentation products were quantified. The results were evaluated by analysis of variance and compared using the Tukey test (P<0.05), using the basal immunological parameters as a covariate. The inclusion of YCWs reduced fat digestibility (P<0.05), increased the concentration of butyrate and putrescine, and reduced lactate in feces (P<0.05), showing that mannan oligosaccharide solubilization resulted in higher fermentation of this compound and altered the metabolism of the gut microbiota. Lower IL-6 on serum was verified for dogs fed the YCWs diet (P<0.05), suggesting a reduction in the inflammatory activity of dogs. Higher phagocytic index was verified for peripheral monocytes after the intake of the YCW food, suggesting better innate immunity. In conclusion, the solubilization of the mannooligosaccharide fraction alters its interaction with gut microbiota and biological actions in animals, although both yeast cell wall preparations exhibited prebiotic effects on dogs.

Role of colonic microbiota in the pathogenesis of ulcerative colitis

BACKGROUND

Recent studies have found gut microbiota to be closely associated with onset and perpetuation of UC. Currently, studies about gut microbiota have mainly covered samples collected from the intestinal lumen. However, the luminal flora is only part of the gut microbiota. Studies of the changes in mucosal flora under pathological conditions have been lacking. In this study, we investigated the correlation between the onset of UC and flora changes in different intestinal layers.

METHODS

The dextran sulfate sodium(DSS)-induced UC model was established by exposing mice to cycles of DSS. The luminal contents, an inner mucus layer, and outer mucus layer were harvested under sterile conditions. The samples were then analyzed using high-throughput sequencing of 16S rRNA V3 + V4 amplicons. The colonic microbiota composition and diversity were analyzed and compared using MetaStat, LefSe, multivariate analysis of variance, and spatial statistics.

RESULTS

The DSS-induced UC mouse model was successfully established. The diversity of the microbiota from luminal content, the outer mucus layer, and inner mucus layer were significantly different in both control and UC model groups. The statistically different OTUs belonged to Lachnospiraceae and Ruminococcaceae families within the order Clostridiales were mainly localized to the outer mucus layer.

CONCLUSIONS

The alterations in flora composition and diversity mainly occurred in the colonic outer mucus layer. The change of flora in the colonic mucus layers is of great significance in the understanding of common features of gut flora in IBD and the understanding of the relationship between gut flora and disease progression.

Immunometabolism and the Kinome Peptide Array: A New Perspective and Tool for the Study of Gut Health

Immunometabolism is a relatively new research perspective, focusing on both metabolism and immunology and the cross-talk between these biological processes. Immunometabolism can be considered from two perspectives; 1) the role that immune cells play in organ metabolism and metabolic disease, and 2) the metabolic processes that occur within immune cells and how they affect overall immunity. The gut may be the prototypical organ of immunometabolism. The gut is the site of nutrient absorption and is a major, if not the major, immune organ. We also describe the integration of kinomics and the species-specific peptide array to the study of the gut. This unique immunometabolic tool combined with the unique immunometabolic nature of the gut provides significant research potential to many animal health applications.

Up-regulation of MDP and tuftsin gene expression in Th1 and Th17 cells as an adjuvant for an oral Lactobacillus casei vaccine against anti-transmissible gastroenteritis virus

The role of muramyl dipeptide (MDP) and tuftsin in oral immune adjustment remains unclear, particularly in a Lactobacillus casei (L. casei) vaccine. To address this, we investigated the effects of different repetitive peptides expressed by L. casei, specifically the MDP and tuftsin fusion protein (MT) repeated 20 and 40 times (20MT and 40MT), in mice also expressing the D antigenic site of the spike (S) protein of transmissible gastroenteritis virus (TGEV) on intestinal and systemic immune responses and confirmed the immunoregulation of these peptides. Treatment of mice with a different vaccine consisting of L. casei expressing MDP and tuftsin stimulated humoral and cellular immune responses. Both 20MT and 40MT induced an increase in IgG and IgA levels against TGEV, as determined using enzyme-linked immunosorbent assay. Increased IgG and IgA resulted in the activation of TGEV-neutralising antibody activity in vitro. In addition, 20MT and 40MT stimulated the differentiation of innate immune cells, including T helper cell subclasses and regulatory T (Treg) cells, which induced robust T helper type 1 and T helper type 17 (Th17) responses and reduced Treg T cell immune responses in the 20MT and 40MT groups, respectively. Notably, treatment of mice with L. casei expressing 20MT and 40MT enhanced the anti-TGEV antibody immune responses of both the humoral and mucosal immune systems. These findings suggest that L. casei expressing MDP and tuftsin possesses substantial immunopotentiating properties, as it can induce humoral and T cell-mediated immune responses upon oral administration, and it may be useful in oral vaccines against TGEV challenge.

Proteomic analysis reveals innate immune activity in intestinal transplant dysfunction

BACKGROUND

Many patients with intestinal failure require intestinal transplantation (ITx) to survive. Acute cellular rejection poses a challenge in ITx because its biologic components are incompletely understood. New methodologies for its integrative and longitudinal analysis are needed.

METHODS

In this study, we characterized episodes of acute cellular rejection in ITx recipients using a noninvasive proteomic analysis. Ostomy effluent was obtained from all patients undergoing ITx at University of California, Los Angeles from July 2008 to September 2009 during surveillance endoscopies in the first 8 weeks post-ITx. Effluent was analyzed using 17-plex Luminex technology and matrix-assisted laser desorption/ionization proteomics.

RESULTS

Of 56 ostomy effluent samples from 17 ITx recipients, 14% developed biopsy-proven rejection at a median of 25 days post-ITx. Six had mild rejection, two were indeterminate for rejection, and no graft loss was seen in the first 3 months posttransplantation. Effluent levels of five innate immune cytokines were elevated in the posttransplantation phase: granulocyte colony-stimulating factor, interleukin-8, tissue necrosis factor-α, interleukin-1β, and interferon-γ. Proteomic analysis revealed 17 protein features differentially seen in rejection, two identified as human neutrophil peptide 1 and 2. This was confirmed by the presence of human neutrophil peptide-positive lamina propria neutrophils in biopsy tissue samples.

CONCLUSIONS

Proteomic and cytokine analysis of ostomy effluents suggests an early and unappreciated role of innate immune activation during rejection.

Acquired immune heterogeneity and its sources in human helminth infection

Similarities in the immunobiology of different parasitic worm infections indicate that co-evolution of humans and helminths has shaped a common anti-helminth immune response. However, recent in vitro and immuno-epidemiological studies highlight fundamental differences and plasticity within host-helminth interactions. The 'trade-off' between immunity and immunopathology inherent in host immune responses occurs on a background of genetic polymorphism, variable exposure patterns and infection history. For the parasite, variation in life-cycle and antigen expression can influence the effector responses directed against them. This is particularly apparent when comparing gastrointestinal and tissue-dwelling helminths. Furthermore, insights into the impact of anti-helminthic treatment and co-infection on acquired immunity suggest that immune heterogeneity arises not from hosts and parasites in isolation, but also from the environment in which immune responses develop. Large-scale differences observed in the epidemiology of human helminthiases are a product of complex host-parasite-environment interactions which, given potential for exposure to parasite antigens in utero, can arise even before a parasite interacts with its human host. This review summarizes key differences identified in human acquired immune responses to nematode and trematode infections of public health importance and explores the factors contributing to these variations.

Allergic rhinitis caused by food allergies

Food allergies occur in 1-2% of adults and in 8% of children under 6 years of age. Food-induced allergies are immunological reactions that cause a variety of symptoms affecting the skin, gastrointestinal tract, and respiratory tract. The reactions are mediated by both IgE- and non-IgE-dependent (cellular) mechanisms. Isolated food-induced allergic rhinitis is not common as it frequently occurs together with other food allergy symptoms such as asthma, eczema, oral allergic manifestations, urticaria, and gastrointestinal symptoms. The present paper provides an overview of food allergies and food-induced allergic rhinitis.

Mucosal immunization using proteoliposome and cochleate structures from Neisseria meningitidis serogroup B induce mucosal and systemic responses

Most pathogens either invade the body or establish infection in mucosal tissues and represent an enormous challenge for vaccine development by the absence of good mucosal adjuvants. A proteoliposome-derived adjuvant from Neisseria meningitidis serogroup B (AFPL1, Adjuvant Finlay Proteoliposome 1) and its derived cochleate form (Co, AFCo1) contain multiple pathogen-associated molecular patterns as immunopotentiators, and can also serve as delivery systems to elicit a Th1-type immune response. The present studies demonstrate the ability of AFPL1and AFCo1 to induce mucosal and systemic immune responses by different mucosal immunizations routes and significant adjuvant activity for antibody responses of both structures: a microparticle and a nanoparticle with a heterologous antigen. Therefore, we used female mice immunized by intragastric, intravaginal, intranasal or intramuscular routes with both structures alone or incorporated with ovalbumin (OVA). High levels of specific IgG antibody were detected in all sera and in vaginal washes, but specific IgA antibody in external secretions was only detected in mucosally immunized mice. Furthermore, antigen specific IgG1 and IgG2a isotypes were all induced. AFPL1 and AFCo1 are capable of inducing IFN-gamma responses, and chemokine secretions, like MIP-1alpha and MIP-1beta. However, AFCo1 is a better alternative to induce immune responses at mucosal level. Even when we use a heterologous antigen, the AFCo1 response was better than with AFPL1 in inducing mucosal and systemic immune responses. These results support the use of AFCo1 as a potent Th1 inducing adjuvant particularly suitable for mucosal immunization.

Board-invited review: porcine mucosal immunity of the gastrointestinal tract

The gastrointestinal tract (GIT) constitutes one of the largest immunological organs of the body. The GIT must permit absorption of nutrients while also maintaining the ability to respond appropriately to a diverse milieu of dietary and microbial antigenic components. Because of the diverse population of antigenic components within the GIT, a sophisticated mucosal immune system has evolved that relies on collaboration between the innate and adaptive arms of immunity. The collaborative, mucosal immune effort offers protection from harmful pathogens while also being tolerant of dietary antigens and normal microbial flora. Knowledge with respect to porcine mucosal immunity is important as we strive to understand the interrelationships among GIT physiology, immunology, and the resident microbiota. The aim of this review is to provide a descriptive overview of GIT immunity and components of the mucosal immune system and to highlight differences that exist between the porcine species and other mammals.

Guanylyl cyclase C-induced immunotherapeutic responses opposing tumor metastases without autoimmunity

BACKGROUND

One of the greatest impediments to cancer immunotherapy is the paucity of antigens that are tumor specific, sufficiently immunogenic, and shared among patients. Mucosa-restricted antigens that are expressed by tumor cells represent a novel class of vaccine targets that are characterized by immunologic privilege, which limits systemic tolerance to those antigens, and immunologic partitioning, which shields mucosae from systemic autoimmune responses. Here we defined the immunogenicity and antitumor efficacy of guanylyl cyclase C (GCC), a protein that is normally restricted to intestinal mucosa and universally expressed by metastatic colorectal cancer.

METHODS

BALB/c mice (n = 197) were immunized with recombinant GCC-expressing viral vectors before (prophylactic) or after (therapeutic) a lethal challenge of GCC-expressing mouse colon cancer cells, and antitumor efficacy was monitored by quantifying metastasis and survival. Induction of autoimmunity was monitored by histopathology. Induction of GCC-specific B-cell and CD4(+) and CD8(+) T-cell responses were determined by enzyme-linked immunosorbent assay and ELISpot, respectively. Tolerance to GCC was quantified by comparing responses in GCC-deficient (n = 45) and wild-type (n = 69) C57BL/6 mice. Statistical tests were two-sided.

RESULTS

Immunization with GCC-expressing viral vectors reduced the formation of metastases to liver (control vs GCC: mean = 30.4 vs 3.55 nodules, difference = 26.9 nodules, 95% confidence interval [CI] = 8.47 to 45.3 nodules; P = .008) and lung (control vs GCC: mean = 263 vs 55.7 nodules, difference = 207, 95% CI = 163 to 251; P < .001) and extended the median survival of mice with established lung metastases following therapeutic immunization (control vs GCC: 29 vs 38 days, P = .024), without autoimmunity. Antitumor efficacy reflected asymmetrical tolerance that was characterized by CD8(+) T-cell, but not CD4(+) T-cell or antibody, responses.

CONCLUSIONS

Immunologic partitioning together with immunologic privilege highlight the potential of mucosa-restricted antigens, particularly GCC, as therapeutic targets for metastatic cancer.

Mechanisms of allergy and asthma

Allergies are the result of an inappropriate reaction against innocuous environmental proteins. The prevalence and severity of allergic diseases has increased dramatically during the last decade in developed countries. Allergen-specific T helper (Th) cells play a pivotal role in the pathogenesis of allergic hypersensitivity reactions. These Th cells activate a complex immune reaction that triggers the release of potent mediators and enhances the recruitment of inflammatory cells, which in turn elicit an inflammatory response that leads to the clinical symptoms of allergic disease. The current therapies for allergic diseases focus primarily on control of symptoms and suppression of inflammation, without affecting the underlying cause. However, the knowledge about the pathophysiology of allergic diseases has substantially increased, offering new opportunities for therapeutic intervention. In this review, we will focus on current insights into the mechanism of allergic reactions.

Oral vaccination: where we are?

As early as 900 years ago, the Bedouins of the Negev desert were reported to kill a rabid dog, roast its liver and feed it to a dog-bitten person for three to five days according to the size and number of bites [1] . In sixteenth century China, physicians routinely prescribed pills made from the fleas collected from sick cows, which purportedly prevented smallpox. One may dismiss the wisdom of the Bedouins or Chinese but the Nobel laureate, Charles Richet, demonstrated in 1900 that feeding raw meat can cure tuberculous dogs - an approach he termed zomotherapy. Despite historical clues indicating the feasibility of oral vaccination, this particular field is notoriously infamous for the abundance of dead-end leads. Today, most commercial vaccines are delivered by injection, which has the principal limitation that recipients do not like needles. In the last few years, there has been a sharp increase in interest in needle-free vaccine delivery; new data emerges almost daily in the literature. So far, there are very few licensed oral vaccines, but many more vaccine candidates are in development. Vaccines delivered orally have the potential to take immunization to a fundamentally new level. In this review, the authors summarize the recent progress in the area of oral vaccines.

Significance of intraepithelial lymphocytes in appendix

The aim of this study was to investigate the importance of the increase in intraepithelial lymphocytes (IELs) in the mucosa of the appendix. One hundred and four retrospective appendectomy specimens were examined to evaluate the IELs. Intraepithelial lymphocytosis was identified in 11.5% (12 cases) of the specimens. Of these 12 cases, 6 cases with intraepithelial lymphocytosis were associated with parasitic infection. No increase in IELs was found in the 36 appendices that were removed in other primary operations. A wide range of immunologic stimuli can raise IELs in the gastrointestinal system. However, in appendectomies with clinical signs of acute appendicitis, an increase in IELs is more likely to be related to parasitic infection. This increase should be considered for the diagnosis of parasitic infections.

Mucosally restricted antigens as novel immunological targets for antitumor therapy

Colorectal cancer is the third most common malignancy and the second most common cause of cancer-related mortality worldwide. While surgery remains the mainstay of therapy, approximately 50% of persons who undergo resection develop parenchymal metastatic disease. Unfortunately, current therapeutic regimens offer little improvement in survival. Using immunotherapy to fill this therapeutic gap has enjoyed limited success, reflecting a paucity of tumor-associated antigens. In that context, there is a significant unrealized opportunity to exploit structural and functional immune system compartmentalization to generate a therapeutic immune response against metastatic colorectal tumors employing biomarkers whose expression is normally confined to intestinal epithelial cells and their derivative malignancies. This novel class of biomarkers, here termed cancer mucosa antigens, may fill the unmet therapeutic need for colorectal cancer-associated immune targets. As a concrete example, guanylyl cyclase C is an intestinal mucosa-specific biomarker ideally suited to test this hypothesis and serve as the first cancer mucosa antigen for colorectal cancer immunotherapy. Here, we discuss colorectal cancer immunity, immune compartmentalization and preliminary results targeting guanylyl cyclase C in mouse models of colorectal cancer, as well as the potential paradigm shift to employing cancer mucosa antigens in immunotherapy of colorectal cancer.

Duodenal intraepithelial T lymphocytes in patients with functional dyspepsia

AIM: To quantify the intraepithelial lymphocytes (IELs) and to document the membrane expression of CD4, CD8, TCRγδ and adhesion and/or activation-associated molecules (CD103, CD28, CD44, CD69, HLA-DR, CD95/Fas) in the duodenal mucosa of patients with functional dyspepsia (FD) in order to provide arguments for an immunological process in FD.

METHODS: Twenty-six FD patients according to Rome II criteria (20 were H pylori negative) were studied and compared to 12 healthy adults. IELs were isolated from five duodenal biopsy samples, then quantified by microscopy and flow cytometry while the membrane phenotypes were determined by cytofluorometry.

RESULTS: Duodenal histological examination was normal. In H pylori negative patients, the number of IELs was not different from that in healthy controls. Median percentage expression of CD4, CD8, or TCRγδ and CD103, CD44, CD28, CD69 on CD3+ IELs, among the adhesion/activation associated molecules tested, was not different from that in healthy controls. In contrast, the median percentage expression of CD95/Fas [22 (9-65) vs 45 (19-88), P = 0.03] and HLA-DR expressing CD3+ IELs [4 (0-30) vs 13 (4-42), P = 0.04] was significantly lower in the H pylori negative FD group than in healthy controls, respectively. The number of IELs was significantly greater in H pylori positive FD patients than in healthy controls [median ratiofor 100 enterocytes 27.5 (6.7-62.5) vs 10.8 (3-33.3), P = 0.02] due to a higher number of CD8+ CD3+ IELs.

CONCLUSION: In H pylori negative FD patients, the phenotypic characterization of IELs suggests that we cannot exclude a role of IELs in FD.

Treating irritable bowel syndrome with a food elimination diet followed by food challenge and probiotics

OBJECTIVE

In Irritable Bowel Syndrome, the gut-associated immune system may be up-regulated resulting in immune complex production, low-grade inflammation, loss of Class I bacteria, and translocation of inflammatory mediators and macromolecules outside of the GI lumen. Since food intolerance may be one of the reasons for this upregulation, our goal was to investigate the role of food intolerance in IBS patients.

METHODS

In this open label pilot study, we enrolled 20 patients with IBS by Rome II criteria (15 women, ages 24-81) who had failed standard medical therapies in a tertiary care GI clinic. Baseline serum IgE and IgG food and mold panels, and comprehensive stool analysis (CSA) were performed. Breath-hydrogen testing and IBS Quality-of-Life (QOL) questionnaires were obtained. Patients underwent food elimination diets based on the results of food and mold panels followed by controlled food challenge. Probiotics were also introduced. Repeat testing was performed at 6-months. We followed up with this cohort at 1 year after trial completion to assess the reported intervention and for placebo effect.

RESULTS

Baseline abnormalities were identified on serum IgG food and mold panels in 100% of the study subjects with significant improvement after food elimination and rotation diet (p < 0.05). Significant improvements were seen in stool frequency (p < 0.05), pain (p < 0.05), and IBS-QOL scores (p < 0.0001). Imbalances of beneficial flora and dysbiotic flora were identified in 100% of subjects by CSA. There was a trend to improvement of beneficial flora after treatment but no change in dysbiotic flora. The 1-year follow up demonstrated significant continued adherence to the food rotation diet (4.00 +/- 1.45), minimal symptomatic problems with IBS (4.00 +/- 1.17), and perception of control over IBS (4.15 +/- 1.23). The continued use of probiotics was considered less helpful (3.40 +/- 1.60).

CONCLUSION

These data demonstrate that identifying and appropriately addressing food sensitivity in IBS patients not previously responding to standard therapy results in a sustained clinical response and impacts on overall well being and quality of life in this challenging entity.

Expression of nonclassical class I molecules by intestinal epithelial cells

It is well recognized that the nature of the immune response is different in the intestinal tract than in peripheral lymphoid organs. The immunologic tone of the gut-associated lymphoid tissue is one of suppression rather than active immunity, distinguishing pathogens from normal flora. Failure to control mucosal immune responses may lead to inflammatory diseases such as Crohn's disease (CD) and ulcerative colitis (UC) and celiac disease. It has been suggested that this normally immunosuppressed state may relate to unique antigen-presenting cells and unique T-cell populations. The intestinal epithelial cell (IEC) has been proposed to act as a nonprofessional antigen-presenting cell (APC). Previous studies have suggested that antigens presented by IECs result in the activation a CD8(+) regulatory T-cell subset in a nonclassical MHC I molecule restricted manner. We therefore analyzed the expression of nonclassical MHC I molecules by normal IECs and compared this to those expressed by inflammatory bowel disease (IBD) IECs. Normal surface IEC from the colon and, to a much lesser extent, the small bowel express nonclassical MHC I molecules on their surface. In contrast, mRNA is expressed in all intestinal epithelial cells. Surface IEC express CD1d, MICA/B, and HLA-E protein. In contrast, crypt IECs express less or no nonclassical MHC I molecules but do express mRNA for these molecules. Furthermore, the regulation of expression of distinct nonclassical class I molecules is different depending on the molecule analyzed. Interestingly, IECs derived from patients with UC fail to express any nonclassical MHC I molecules (protein and HLA-E mRNA). IECs from CD patients express HLA-E and MICA/B comparable to that seen in normal controls but fail to express CD1d. Thus, in UC there may be a failure to activate any nonclassical MHC I molecule restricted regulatory T cells that may result in unopposed active inflammatory responses. In CD only the CD1d-regulated T cells would be affected.

Food allergy in gastroenterologic diseases: Review of literature

Food allergy is a common and increasing problem worldwide. The newly-found knowledge might provide novel experimental strategies, especially for laboratory diagnosis. Approximately 20% of the population alters their diet for a perceived adverse reaction to food, but the application of double-blind placebo-controlled oral food challenge, the “gold standard” for diagnosis of food allergy, shows that questionnaire-based studies overestimate the prevalence of food allergies. The clinical disorders determined by adverse reactions to food can be classified on the basis of immunologic or nonimmunologic mechanisms and the organ system or systems affected. Diagnosis of food allergy is based on clinical history, skin prick tests, and laboratory tests to detect serum-food specific IgE, elimination diets and challenges. The primary therapy for food allergy is to avoid the responsible food. Antihistamines might partially relieve oral allergy syndrome and IgE-mediated skin symptoms, but they do not block systemic reactions. Systemic corticosteroids are generally effective in treating chronic IgE-mediated disorders. Epinephrine is the mainstay of treatment for anaphylaxis. Experimental therapies for IgE-mediated food allergy have been evaluated, such as humanized IgG anti-IgE antibodies and allergen specific immunotherapy.

Addressing the "New" NEC: Part I: rediscovering the basics

Epithelial cell functions ultimately define the ability of the extremely low birth weight human fetus to survive outside of the uterus. These specialized epithelial cell capacities manage all human interactions with the ex utero world including: (i) lung mechanics, surface chemistry and gas exchange, (ii) renal tubular balance of fluid and electrolytes, (iii) barrier functions of the intestine and skin for keeping bacteria out and water in, plus enabling intestinal digestion, as well as (iv) maintaining an intact neuroepithelium lining of the ventricles of the brain and retina. In Part I of this two part review, the authors describe why the gut barrier is a clinically relevant model system for studying the complex interplay between innate and adaptive immunity, dendritic &epithelial cell interactions, intraepithelial lymphocytes, M-cells, as well as the gut associated lymphoid tissues where colonization after birth, clinician feeding practices, use of antibiotics as well as exposure to prebiotics, probiotics and maternal vaginal flora all program the neonate for a life-time of immune competence distinguishing "self" from foreign antigens. These barrier defense capacities become destructive during disease processes like necrotizing enterocolitis (NEC) when an otherwise maturationally normal, yet dysregulated and immature, immune defense system is associated with high levels of certain inflammatory mediators like TNFa. In Part II, the authors will discuss the theoretical advantages of using rhG-CSF in managing NEC or sepsis by augmenting neonatal neutrophil number and killing capacity including an unexpected, paradoxical and potent anti-TNFa function that may serve to limit extension of tissue destruction without impairing bacterial killing capacity. The authors conclude by arguing that NEC may be the ideal disease process for testing whether a clearly defined clinical benefit of cytokine therapy can prove beneficial.

Chronic psychological stress in rats induces intestinal sensitization to luminal antigens

There is increasing evidence that stress plays a role in the pathophysiology of chronic intestinal disorders, but the mechanisms remain unclear. Previous studies in rats have revealed that stress decreases gut barrier function and allows excessive uptake of luminal material. Here, we investigated whether chronic psychological stress acts to induce sensitization of intestinal tissues to oral antigens. Rats were subjected to 1 hour per day of water avoidance stress or sham stress daily for 10 days, and horseradish peroxidase (HRP) was delivered by gavage on day 5. Studies to determine sensitization were conducted on day 20. All stressed rats developed HRP-specific IgE antibodies, antigen-induced intestinal secretion, and increased numbers of inflammatory cells in gut mucosa. Luminal HRP was absorbed more readily by enterocytes of stressed animals. In addition, stressed rats had increased expression of interleukin-4 and decreased expression of interferon-gamma in gut mucosa, a cytokine profile that is typical of allergic conditions. Treatment of stressed rats with an antagonist to corticotropin-releasing hormone (previously shown to inhibit stress-enhanced gut permeability) eliminated the manifestations of intestinal hypersensitivity. Our results indicate that the presence of oral antigen during chronic psychological stress alters the immune response (to sensitization rather than oral tolerance) and causes subsequent antigen-induced gut pathophysiology.

Pediatric food allergy update

Food allergy is mostly a childhood disease that differs from the adult-onset allergy in several aspects, including the prevalence, commonly offending foods, symptomatology, and prognosis. The prevalence is much overestimated by the public, but it probably affects up to 6% of children. In some cases, the diagnosis might be clearly evident, but in most cases an expert evaluation may be needed that usually includes verification by challenge testing. Currently, the management of food allergy is avoidance of the offending foods together with the availability of pharmacologic agents for symptomatic treatment, including self-administered epinephrine. The latter is of utmost importance in highly allergic subjects because accidental trivial exposure is not uncommon. Recent studies promise immunomodulatory agents that might be of potential use for prophylaxis. One such agent is anti-immunoglobulin E, which might be available in the near future.

Adverse reactions to foods

Food allergy encompasses a variety of immune-mediated adverse reactions to foods. IgE-mediated, cell-mediated, and mixed-mechanism food allergy disorders are recognized. Over the past 2 decades, the prevalence of food allergy doubled and its phenotypic expression increased in Westernized societies. Major food allergens have been identified for many common foods. Laboratory diagnosis of food allergy relies heavily on the detection of food-specific IgE antibodies, but novel approaches include tests for T-cell-mediated disorders and tests for prediction of tolerance. OFC remains the diagnostic standard for food allergy. Management of food allergy focuses on avoidance of the offending foods, nutritional support, and prompt recognition and treatment of acute food allergic reactions. Anti-IgE monoclonal antibody is the first potential therapy for food allergy that is under-going testing in clinical trials.

Pathological and clinical significance of increased intraepithelial lymphocytes (IELs) in small bowel mucosa

Intestinal intraepithelial lymphocytes (IELs) belong to a unique T-cell population interspersed between epithelial cells of both the small and large intestine. It is becoming increasingly recognised that an increased number of IELs with a normal villous architecture is within the wide spectrum of histological abnormalities observed in coeliac disease. An increased number of IELs is the earliest pathological change following gluten challenge and a high IEL count may be the only sign of gluten sensitivity. Therefore, the finding of a raised IEL count with normal villous architecture is of sufficient clinical importance to be reported in routine small bowel biopsies. However, it is evident that not all small intestinal biopsy specimens showing increased IELs are explained by gluten sensitivity. Increased IELs in small bowel mucosa have also been associated with autoimmune disorders, tropical sprue, food protein intolerance, Helicobacter pylori-associated gastritis, peptic duodenitis, parasitic and viral infections, as well as the development of intestinal lymphoma. Histological examination of a biopsy specimen of the small bowel remains the diagnostic gold standard for coeliac disease. There will be an ever increasing demand for histological confirmation of gluten sensitivity in patients in whom the classic microscopic appearance of flattened villi may not have fully developed. The more widespread recognition by histopathologists of the pattern of injury manifested by increased numbers of IELs in intestinal biopsy specimens will certainly help in early diagnosis of coeliac disease, lessen diagnostic confusion and influence the modern practice of gastrointestinal tract medicine. This review discusses some of the recent developments in clinical pathology pertaining to increased IELs in small bowel mucosal biopsies.

Inflammatory bowel disease: dysfunction of GALT and gut bacterial flora (I)

Gut-associated lymphoid tissue (GALT) is the largest lymphoid organ in the body. This is not surprising considering the huge load of antigens (Ags) from food and commensal bacteria with which it interacts on a daily basis. Gut-associated lymphoid tissue has to recognise and allow the transfer of beneficial Ags whilst concurrently dealing with and successfully removing putative and overtly harmful Ags. This distinctive biological feature of GALT is believed to be crucial to good health. Deregulation or dysfunction of GALT is thought to predispose to inflammatory bowel diseases (IBD) such as ulcerative colitis and Crohn's disease. The exact mechanism(s) underlying the pathogenesis of IBD is (are) poorly understood and the immunological defects in GALT are poorly documented. Advances in immunology have highlighted the importance of dendritic cells (DCs), which are the key Ag presenting cells in tissues and lymphoid compartments. Their crucial role in GALT, in health and disease is discussed in this review. Interaction of DCs with T cells in the gut produces a subset of T lymphocytes, which have immunosuppressive function. Inappropriate Ag uptake and presentation to naïve T cells in mesenteric lymph nodes may lead to T cell tolerance in GALT. These various complex factors in the gut are discussed and their possible relevance to IBD evaluated.

The effects of long-term total parenteral nutrition on gut mucosal immunity in children with short bowel syndrome: a systematic review

BACKGROUND: Short bowel syndrome (SBS) is defined as the malabsorptive state that often follows massive resection of the small intestine. Most cases originate in the newborn period and result from congenital anomalies. It is associated with a high morbidity, is potentially lethal and often requires months, sometimes years, in the hospital and home on total parenteral nutrition (TPN). Long-term survival without parenteral nutrition depends upon establishing enteral nutrition and the process of intestinal adaptation through which the remaining small bowel gradually increases its absorptive capacity. The purpose of this article is to perform a descriptive systematic review of the published articles on the effects of TPN on the intestinal immune system investigating whether long-term TPN induces bacterial translocation, decreases secretory immunoglobulin A (S-IgA), impairs intestinal immunity, and changes mucosal architecture in children with SBS. METHODS: The databases of OVID, such as MEDLINE and CINAHL, Cochran Library, and Evidence-Based Medicine were searched for articles published from 1990 to 2001. Search terms were total parenteral nutrition, children, bacterial translocation, small bowel syndrome, short gut syndrome, intestinal immunity, gut permeability, sepsis, hyperglycemia, immunonutrition, glutamine, enteral tube feeding, and systematic reviews. The goal was to include all clinical studies conducted in children directly addressing the effects of TPN on gut immunity. RESULTS: A total of 13 studies were identified. These 13 studies included a total of 414 infants and children between the ages approximately 4 months to 17 years old, and 16 healthy adults as controls; and they varied in design and were conducted in several disciplines. The results were integrated into common themes. Five themes were identified: 1) sepsis, 2) impaired immune functions: In vitro studies, 3) mortality, 4) villous atrophy, 5) duration of dependency on TPN after bowel resection. CONCLUSION: Based on this exhaustive literature review, there is no direct evidence suggesting that TPN promotes bacterial overgrowth, impairs neutrophil functions, inhibits blood's bactericidal effect, causes villous atrophy, or causes to death in human model.The hypothesis relating negative effects of TPN on gut immunity remains attractive, but unproven. Enteral nutrition is cheaper, but no safer than TPN. Based on the current evidence, TPN seems to be safe and a life saving solution.

Regulatory T cells: peace keepers in the gut

The mucosa-associated lymphoid tissue (MALT) has the task of protecting the host from pathogens while maintaining the integrity of the gut. Immune responses are tightly regulated such that there is tolerance of nonpathogenic bacteria as well as dietary antigens present in the intestinal lumen. The failure to control these responses leads to a disruption in tolerance, which has been proposed as one mechanism involved in the development of inflammatory bowel disease (IBD). Different mechanisms are involved in the control of immune responses in the intestinal tract, including active suppression by regulatory T cells. Distinct subsets of regulatory T cells coexist in the intestinal mucosa, which is a fertile environment for their growth. Most of these are defined by their phenotype and/or their ability to produce regulatory cytokines such as interleukin-10 and transforming growth factor-beta A lack of activation and/or expansion of regulatory cells could play a role in the uncontrolled inflammation seen in IBD. Regulatory T cells may be activated by cytokines, and their inductive phase may be antigen-driven. There are limited data relating to the true surface interactions regulating the activation of these cells. Most of the CD4 regulatory T cells (Tr1, Th3, and CD4 CD25+) are thought to interact with dendritic cells. Subsets of regulatory T cells (such as CD8 TrE cells) may recognize antigens presented by intestinal epithelial cells. A better understanding of the mechanisms by which these regulatory T cells are expanded and/or activated in the intestinal mucosa may provide clues as how to use them as a novel therapeutic tool in the treatment of patients with IBD.

Interferon gamma downregulates IL-8 production in primary human colonic epithelial cells without induction of apoptosis

BACKGROUND

In acute or chronic inflammatory bowel disease (IBD) interferon gamma (IFNgamma) is still considered to be an important pro-inflammatory mediator. In the present study we investigated the impact of IFNgamma on interleukin-8 (IL-8) production as a read-out for cell activation in intestinal epithelial cell (IEC) lines and primary human colonic epithelial cells (CEC).

METHODS

Primary cultures of human CEC were established from the mucosa of patients without inflammatory disease. CEC, HT-29 or Caco-2 cells were incubated with either IFNgamma, tumor necrosis factor (TNF)alpha or IL-10. IL-8 and IL-1Ra secretion was determined by ELISA. Competicon PCR was used for quantification of IL-8mRNA. Apoptosis was quantified by propidium iodine incorporation and fluorescence activated cell sorting (FACS) analysis.

RESULTS

In contrast to HT-29 cells in primary human CEC 100 U/ml IFNgamma inhibited IL-8 secretion significantly to 70+/-15% of unstimulated primary CEC (p<0.005) more effectively than IL-10 (87+/-21% versus unstimulated cells, n.s.). In HT-29 cells, IL-8 secretion was induced to 405+/-101% of unstimulated cells. In Caco-2 cells, IFNgamma had no significant effect on IL-8 secretion. The effect in HT-29 and CEC was concentration dependent. In primary CEC, 200 U/ml IFNgamma further reduced IL-8 secretion to 48+/-18% of unstimulated CEC (p<0.05). Whereas IL-8 mRNA was strongly upregulated in HT-29 cells, no upregulation or even a downregulation was found in CEC. Pre-incubation with 100 U/ml IFNgamma did not increase the susceptibility to apoptosis mediated by anti-Fas antibody (CH-11) in primary CEC, whereas HT-29 cells showed increased rates of apoptosis after priming with IFNgamma.

CONCLUSION

In contrast to HT-29, IFNgamma downregulated IL-8 secretion and did not induce IL-8 mRNA expression in primary human CEC. This effect was not due to induction of apoptosis.

Deficiencies in gut NK cell number and function precede diabetes onset in BB rats

Defects in the intestinal immune system may contribute to the pathogenesis of autoimmune diseases. Intraepithelial lymphocytes represent a substantial fraction of gut-associated lymphocytes, but their function in mucosal immunity is unclear. A newly described population of NK cells that spontaneously secrete IL-4 and IFN-gamma is present in the intraepithelial lymphocyte compartment of the rat. We hypothesized that defects in the number or function of these cells would be present in rats susceptible to autoimmunity. We report that the number of NKR-P1A(+)CD3(-) intraepithelial NK (IENK) cells is deficient before onset of spontaneous autoimmune diabetes in diabetes-prone BB (BBDP) rats. The absolute number of recoverable IENK cells was only approximately 8% of that observed in WF rats. Bone marrow transplantation from histocompatible WF donors reversed the IENK cell deficiency (and prevented diabetes) in these animals, suggesting a hemopoietic origin for their IENK cell defect. Analysis of diabetes-resistant BB rats, which develop autoimmune diabetes only after perturbation of the immune system, revealed IENK cell numbers intermediate between that of BBDP and WF rats. IENK cells were selectively depleted during treatment to induce diabetes. Prediabetic BBDP and diabetes-resistant BB animals also exhibited defective IENK cell function, including decreased NK cell cytotoxicity and reduced secretion of IL-4 and IFN-gamma. IENK functional defects were also observed in LEW and BN rats, which are susceptible to induced autoimmunity, but not in WF, DA, or F344 rats, which are resistant. Defects in IENK cell number and function may contribute to the pathogenesis of autoimmune diseases including type 1 diabetes.

9. Food allergy

Food allergies affect as many as 6% of young children, most of whom "outgrow" the sensitivity, and about 2% of the general population. Although any food may provoke a reaction, relatively few foods are responsible for the vast majority of food allergic reactions: milk, egg, peanuts, tree nuts, fish, and shellfish. Many of these food allergens have been characterized at a molecular level, which has increased our understanding of the immunopathogenesis of many responses and may soon lead to novel immunotherapeutic approaches. Food allergic reactions are responsible for a variety of symptoms involving the skin, gastrointestinal tract, and respiratory tract and may be due to IgE-mediated and non-IgE-mediated mechanisms. A systematic approach including history, laboratory studies, elimination diets, and often food challenges will lead to the correct diagnosis. Currently, management of food allergies consists of educating the patient to avoid ingesting the responsible allergen and to initiate therapy in case of an unintended ingestion.

Zinc deficiency suppresses the development of oral tolerance in rats

Oral tolerance is a specific immune unresponsiveness to food antigens to prevent hypersensitivity reactions. We investigated whether zinc deficiency affects oral tolerance. Rats were fed a control (C) or zinc-deficient (ZD) diet, or pair-fed (PF) to ZD rats for 28 d. Beginning on d 7, rats were administered ovalbumin (OVA) orally to induce tolerance, or PBS 3 times/wk, and were then immunized by OVA injection. The proliferation of mesenteric lymph node (MLN) and spleen lymphocytes after in vitro OVA stimulation and the delayed-type hypersensitivity were higher in OVA-fed ZD than in OVA-fed C rats and not different between OVA- and PBS-fed ZD rats, indicating a suppression of tolerance. Lymphocyte proliferation did not differ between PF and C rats. Expressions of cytokines involved in oral tolerance, i.e., interleukin (IL)-4, IL-10 and transforming growth factor-beta, were higher in OVA- than in PBS-fed C rats, but not in ZD rats. Apoptosis was higher in OVA- than in PBS-fed C rats but not different between OVA- and PBS-fed ZD rats. Inflammation and ulcerations that were not present in ZD rats on d 7 (ZD(7)) developed in OVA- or PBS-fed ZD rats. Compared with ZD(7) rats, tumor necrosis factor-alpha and cytokine-induced neutrophil chemoattractant were higher in OVA- and PBS-fed ZD rats, whereas interferon-gamma increased only in OVA-fed ZD rats. In conclusion, zinc deficiency suppresses oral tolerance through dysregulation of cytokine expression and lack of antigen-specific clonal deletion. We suggest that abrogation of tolerance may lead to development of mucosal inflammation and damage.

Heparin-binding EGF-like growth factor preserves crypt cell proliferation and decreases bacterial translocation after intestinal ischemia/reperfusion injury

BACKGROUND/PURPOSE

Heparin-binding epidermal growth factor (EGF)-like growth factor (HB-EGF), a known mitogenic, chemotactic, and cytoprotective growth factor for epithelial cells, was examined to see whether it could protect intestinal barrier function and decrease bacterial translocation (BT) after ischemia/reperfusion (I/R) injury.

METHODS

In vitro, tight junctional integrity of intestinal epithelial cells (IEC-6) cells was evaluated by measuring transepithelial electric resistance (TEER), and monolayer permeability was evaluated by translocation of Escherichia coli C25. In vivo, crypt cell proliferation was assessed by 5-bromodeoxyuridine incorporation with calculation of a proliferative index (PI), and BT was evaluated by culture of mesenteric lymph nodes.

RESULTS

In vitro, anoxia damaged tight junctional integrity and increased permeability of IEC-6 cell monolayers, events that were reversed completely by treatment of the cells with HB-EGF. Twenty-four hours after I/R injury in vivo, crypt cell proliferation index (PI) decreased significantly from 35.6 +/- 4.5 to 17.8 +/- 3.4. Administration of HB-EGF preserved crypt cell activity with PI of 34.9 +/- 4.1, similar to that of normal ileum. None of the normal or sham-operated animals showed BT, whereas BT occurred in 87.5% of I/R-injured rats. In animals exposed to I/R but treated with HB-EGF, BT was decreased significantly to 12.5%.

CONCLUSION

HB-EGF preserves proliferation of crypt cells, maintains integrity of epithelial cells, and subsequently decreases enteric BT after I/R injury.

A similar high level of immunoglobulin A and immunoglobulin G class milk antibodies and increment of local lymphoid tissue on the duodenal mucosa in subjects with cow's milk allergy and recurrent abdominal pains

In previous studies, we have reported endoscopic and histological alterations locally on the gastrointestinal (GI) tract associated with a gastrointestinal type of cow's milk allergy. In this study, we sought to further characterize endoscopic, and immunological findings in these children. We also hypothesized that the same type of immune responses might also be found in children with unexplained and recurrent abdominal pains. We did a gastroduodenoscopy for persistent GI symptoms, examined the mucosal histology of the small intestine and measured the antibodies to whole cow's milk and its fractions with an enzyme-linked immunosorbent assay (ELISA) in a consecutive series of 22 subjects with untreated and 14 with treated cow's milk allergy (CMA) and 44 with recurrent abdominal pains (RAP). The immunological findings of the study subjects were compared with 54 controls. Lymphonodular hyperplasia (LNH) of the duodenum was the main endoscopic finding in 11 subjects (50%) with untreated and 5 (36%) with treated CMA. It was also found in 6 of 44 subjects with RAP. Compared with the controls, the patients with CMA showed significantly higher levels of IgA class antibodies to whole milk (p = 0.003) and betaLG (p < 0.0001). Of the IgG class antibodies to betaLG (p = 0.032), BSA (p < 0.0001) and alphaCAS (p < 0.0001) were significantly higher. The patients with LNH of the duodenal bulb as the main endoscopic finding showed significantly higher values of IgG class antibodies to betaLG (p = 0.01) and alphaCAS (p = 0.005). Interestingly, the patients examined for RAP showed a similar increment in the pattern of whole milk and specific milk protein antibodies as the CMA children. In conclusion this study showed that gastrointestinal CMA beyond infancy is significantly associated with high levels of IgG and IgA class antibodies to milk and its fractions. As high levels of these antibodies and LNH of the duodenal bulb were also found in subjects with RAP, the study further suggests that gastrointestinal CMA might be one major reason for RAP.

Food allergy. Mechanisms, diagnosis, and management in children

We eat approximately two to three tons of food in our lifetime, but most people do not have an adverse reaction to foods. Many people believe that they have an allergic reaction to foods; however, the actual incidence confirmed by history and challenges suggests a prevalence rate closer to 2% to 8% in young infants and less than 2% in adults.

An atypical population of NK cells that spontaneously secrete IFN-gamma and IL-4 is present in the intraepithelial lymphoid compartment of the rat

The intestinal lymphoid compartment of the rat is large and diverse, but the phenotype and functions of its constituent cell populations are not fully characterized. Using new methodology for the isolation and purification of rat intestinal intraepithelial lymphocytes (IELs), we previously identified a population of alphabeta- and gammadelta-TCR- NKR-P1A+ NK cells. These cells were almost completely restricted to the CD4-CD8- IEL population, and unlike peripheral NK cells in the rat, they were CD2-. We now report that rat intraepithelial NK (IENK) and peripheral NK cells are similar in morphology, in their ability to lyse NK-sensitive targets, and in their ability to suppress a one-way mixed lymphocyte culture. In contrast, however, intraepithelial and splenic NK cells differ markedly in two respects. First, IENK cells express high levels of ADP-ribosyltransferase 2 (a marker of regulatory T cells in the rat) and CD25, whereas peripheral NK cells do not. Second, unlike splenic NK cells, a substantial fraction of IENK cells appear to spontaneously secrete IL-4 and/or IFN-gamma. We conclude that the rat IEL compartment harbors a large population of NKR-P1A+CD3- cells that function as NK cells but display an activated phenotype and unusual cytokine profile that clearly distinguish them from splenic NK cells. Their phenotypic and functional characteristics suggest that these distinctive IENK cells may participate in the regulation of mucosal immunity.