Rectal gluten challenge and diagnosis of coeliac disease

Diagnosing coeliac disease: Out with the old and in with the new?

Coeliac disease (CD) is a complex condition resulting from an interplay between genetic and environmental factors. When diagnosing the condition, serological testing and genotyping are useful in excluding CD, although the gold standard of testing is currently histopathological examination of the small intestine. There are drawbacks associated with this form of testing however and because of this, novel forms of testing are currently under investigation. Before we develop completely novel tests though, it is important to ask whether or not we can simply use the data we gather from coeliac patients more effectively and build a more accurate snapshot of CD through statistical analysis of combined metrics. It is clear that not one single test can accurately diagnose CD and it is also clear that CD patients can no longer be defined by discrete classifications, the continuum of patient presentation needs to be recognised and correctly captured to improve diagnostic accuracy. This review will discuss the current diagnostics for CD and then outline novel diagnostics under investigation for the condition. Finally, improvements to current protocols will be discussed with the need for a holistic "snapshot" of CD using a number of metrics simultaneously.

Orally based diagnosis of celiac disease: current perspectives

Celiac disease (CD) is a lifelong immune-mediated disorder caused by the ingestion of wheat gluten in genetically susceptible persons. Most cases of CD are atypical and remain undiagnosed, which exposes the individuals to the risk of life-threatening complications. Serologic endomysial and tissue transglutaminase antibody tests are used to screen at-risk individuals, although a firm diagnosis requires demonstration of characteristic histopathologic findings in the small-intestinal mucosa. A gluten challenge, with a repeat biopsy to demonstrate recurrence of histopathologic changes in the intestinal mucosa after the re-introduction of gluten, is considered for those persons in whom diagnosis remains in doubt. In this paper, we review studies that evaluated: (1) the possibility of using oral mucosa for the initial diagnosis of CD or for local gluten challenge; and (2) the possibility of using salivary CD-associated antibodies as screening tests. Our review shows that orally based diagnosis of CD is attractive and promising, although additional evaluations with standardized collection and analysis methods are needed. There is some evidence of a dissociation between systemic and oral mucosal immune responses in CD. The hypothesis that gluten could stimulate naive lymphocytes directly in the oral cavity would have important implications for the understanding, diagnosis, and management of CD.

Effect of gluten-free diet on preventing recurrence of gastroesophageal reflux disease-related symptoms in adult celiac patients with nonerosive reflux disease

BACKGROUND AND AIM

In celiac disease (CD) the role of a gluten-free diet (GFD) on gastroesophageal reflux disease-related symptoms (GERD-rs) is unclear. The aim of this study was to establish the recurrence of GERD-rs, in CD patients with nonerosive reflux disease (NERD).

METHODS

From a total of 105 adult CD patients observed, 29 who presented with the NERD form were enrolled in the study. Thirty non-CD patients with NERD were studied as controls. Recurrence of GERD-rs was clinically assessed at 6, 12, 18, and 24 months follow-up (FU) after withdrawal of initial proton-pump inhibitor (PPI) treatment for 8 weeks.

RESULTS

GERD-rs were resolved in 25 (86.2%) CD patients and in 20 (66.7%) controls after 8 weeks of PPI treatment. In the CD group, recurrence of GERD-rs was found in five cases (20%) at 6 months but in none at 12, 18, and 24 months while in the control group recurrence was found in six of 20 controls (30%), in another six (12/20, 60%), in another three (15/20, 75%), and in another two (17/20, 85%) at 6, 12, 18, and 24 months FU respectively.

CONCLUSIONS

The present study is the first to have evaluated the effect of a GFD in the nonerosive form of GERD in CD patients, by means of clinical long-term follow-up, suggesting that GFD could be a useful approach in reducing GERD symptoms and in the prevention of recurrence.

Lymphocytic, collagenous and other microscopic colitides: pathology and the relationship with idiopathic inflammatory bowel diseases

SUMMARY

Collagenous colitis and lymphocytic colitis are the two major conditions characterized by chronic watery diarrhoea, without endoscopic or radiological lesions, but with histological abnormalities and therefore considered as "microscopic colitis". The histology of colonic biopsies shows inflammation of the mucosa, and either thickening of the subepithelial collagen band or an increase of lymphocytes in the surface epithelium. Different variant forms have been reported under separate names. These are probably not specific entities. The incidence of microscopic colitis is slightly less than the incidence of chronic idiopathic inflammatory bowel diseases (IBD). Microscopic colitis and IBD are clearly different entities. The relation between both entities is weak but double. Biopsy samples from patients with IBD may mimic the features of lymphocytic or collagenous colitis, both in the initial onset and during follow-up. In the large majority of these cases, endoscopy shows or has shown mucosal lesions. In rare cases, however, a double diagnosis was made. Certain patients, usually of older age, presented first with a microscopic, usually collagenous colitis and developed subsequently genuine ulcerative colitis.

Celiac disease: current concepts in diagnosis and treatment

Celiac disease is a complex autoimmune enteropathy that affects the small bowel in genetically predisposed individuals. It is thought that celiac disease is the result of an inappropriate T cell-mediated immune response against ingested gluten protein. The characteristic lesion of the small intestinal mucosa includes loss of absorptive villi and infiltration of the lamina propria with inflammatory cells. The clinical presentation of celiac disease varies greatly depending on patient's age, duration and extent of the disease, and the presence of extraintestinal manifestations. Unfortunately, most patients with celiac disease have either silent or atypical presentations, thus escaping diagnosis for several years. Medical nutrition therapy with lifelong adherence to a strict gluten-free diet is the only accepted treatment of celiac disease. Individuals at risk for this entity should undergo appropriate serologic testing, but there is no evidence to support mass screening.

The pathogenesis of coeliac disease

Coeliac disease is a common condition and its prevalence in UK is now thought to be approximately 1:100. It is being diagnosed and treated more frequently as awareness at the primary care level has increased. Coeliac disease is a complex disorder and is frequently associated with other disease processes. The management of these patients needs to take on a holistic approach, whilst the physician needs to be aware of the rare complications. This article gives an up-to-date review of the literature written on the pathogenesis of coeliac disease. We have attempted to paint a picture from beginning to end, whilst clarifying the grey areas in between. General epidemiological factors are reviewed before looking at genetic risk factors. We assess the sensitivity and specificity of the investigative modalities available for clinical use and comment on optimum management of these patients thereafter. The future of coeliac disease looks promising for patients with several novel therapies on the horizon. Whilst further work is still needed to breed out the toxic epitopes from wheat, novel therapies may come from other areas such as the work aimed at restoring normal tolerance to gluten.

Gluten-free diet--what is toxic?

The cornerstone of treatment of coeliac disease is a gluten-free diet devoid of proteins from wheat, rye, barley and related cereals. Oats are tolerated by most patients with coeliac disease but are not totally innocent. There are considerable differences between individual patients with respect to clinical and mucosal responses to gluten challenge. In vitro and in vivo testing has identified synthetic peptides that are toxic to the coeliac small intestinal mucosa. This toxicity overlaps at least partly to the known epitopes that are recognised by small intestinal T-cells. However, the clinical significance of several of these epitopes is unclear, as is the maximum level of gluten intake that can be recommended to be safe for patients with coeliac disease. Future efforts may lead to better understanding of the disease processes as well as possible new therapeutic options.

Potential and latent coeliac disease

This case report details a child with coeliac disease and giardiasis. Treatment of the infection without recourse to a gluten-free diet cured the symptoms of diarrhoea and returned the small intestinal morphology to normal. Thus, the patient moved from active to latent coeliac disease. Potential and latent forms of coeliac disease are being increasingly recognized, since markers have become available to identify patients and investigations developed to test for gluten sensitivity in the small intestinal mucosa. This case provides an opportunity to consider potential and latent forms of coeliac disease and how these impact on clinical practice and the wider understanding of the disorder.

The natural history of gluten sensitivity: report of two new celiac disease patients resulting from a long-term follow-up of nonatrophic, first-degree relatives

OBJECTIVE

Early studies revealed that up to 50% of non-atrophic, first-degree relatives of celiac disease patients exhibit features of gluten sensitivity. However, whether these features progress to a fully expressed celiac disease remain partially known. Our aim was to report two new patients resulting from a prospective, long-term surveillance of relatives who were nonatrophic at initial assessment.

METHODS

After a median time of 86 months (range: 42-102 months) from the baseline assessment, we re-evaluated 44 first-degree relatives of propositi who had taken part in family studies and in whom baseline small intestinal biopsies were normal. At the baseline screening, 21 relatives had positive serum antigliadin antibodies and/or increased intraepithelial lymphocyte infiltration, and 23 did not. In addition, 11 of 18 had a celiac-like response to rectal gluten challenge and 16 of 34 possessed the characteristic HLA DQ2 haplotype (DQA1 0501 DQB1 0201). Re-evaluation was based on celiac-related serology antigliadin (AGA) and endomysial (EmA) antibodies. EmA-positive subjects underwent intestinal biopsy.

RESULTS

At the end of the study, EmA was positive in only two subjects. Histological examination revealed flat small bowel mucosa in both. At baseline, both cases were EmA-negative and no minor histological changes were observed. One was a woman with positive baseline IgA and IgG AGA and a rectal gluten challenge with a celiac-like response; the other patient has presented only with a positive IgG AGA. In both cases, progression was detected in a clinically silent context. Both new patients had the characteristic HLA DQ2 haplotype.

CONCLUSIONS

Our data suggest the need to re-evaluate relatives who have been negative on initial screening for celiac disease. Up to now, the progression to severe enteropathy was only observed in relatives who had presented some evidence of gluten sensitivity and the characteristic HLA DQ2 haplotype. Longer longitudinal studies are necessary to obtain definitive conclusions.

The pattern of involvement of the gastric mucosa in lymphocytic gastritis is predictive of the presence of duodenal pathology

AIM

To determine whether the pattern of involvement of the gastric mucosa in lymphocytic gastritis is predictive of the presence or absence of duodenal pathology.

METHODS

50 cases (M:F, 26:24; median age 57 years) diagnosed as lymphocytic gastritis between 1986 and 1998 with concurrent duodenal (D2) biopsies were identified from a computer search of the pathology records and validated by counting gastric intraepithelial lymphocytes. Gastric and duodenal intraepithelial lymphocyte counts were performed on haematoxylin and eosin (H&E) and anti-CD3 stained sections. D2 biopsies were assessed for villous atrophy and chronic inflammatory cell infiltration by subjective grading, and gastritis was classified and graded according to the updated Sydney system. A case was designated corpus predominant when the corpus chronic inflammation grade exceeded that of the antrum. If it was less, then the case was antrum predominant, and if they were equal it was diffuse (pan-) gastritis. The ratio between the corpus and antral intraepithelial lymphocyte count in individual patients was calculated.

RESULTS

Of 50 cases of lymphocytic gastritis, 21 were classified as corpus predominant. With one exception (a case of mild villous atrophy), all were accompanied by normal duodenal morphology. Cases with a corpus predominant gastritis had median duodenal intraepithelial lymphocyte counts of 19 (H&E) and 14.1 (CD3), whereas 29 subjects with an antrum predominant or diffuse gastritis had median counts of 39.9 (H&E) and 37.9 (CD3). Fifteen of these 29 cases (52%) showed villous atrophy; all were graded as moderate or severe. Patients with any degree of villous atrophy had a mean corpus/antrum intraepithelial lymphocyte ratio (H&E) of 0.59 (representing antral predominance), while those with normal duodenal morphology had a ratio of 2.39 (p < 0.0001).

CONCLUSIONS

The pattern of involvement of gastric mucosa in lymphocytic gastritis is closely related to the associated duodenal pathology. Those with the corpus predominant form are unlikely to have duodenal pathology, while those with an antral predominant or diffuse form should have distal duodenal biopsies taken to exclude villous atrophy.

Gluten-free diet induces regression of T-cell activation in the rectal mucosa of patients with celiac disease

OBJECTIVE

An increase in the number of intraepithelial lymphocytes (IEL) in the rectal epithelium of patients with active celiac disease has been described. No data are available about how they vary during a gluten-free diet. The aim of the study was to assess the effect of a gluten-free diet on T-cell activation in the rectal mucosa of adult patients with celiac disease.

METHODS

Frozen duodenal and rectal biopsies were available in four celiac patients (one male, three female, mean age 39 yr) both before and after 7 to 24 months on a gluten-free diet. Biopsy samples were stained using monoclonal antibodies directed against CD3, betaF1, TcRdelta1, CD25, and HLADR. Numbers of IEL were estimated by counting the peroxidase-stained cells per 100 epithelial cells. Four patients without histological abnormalities were used as control subjects.

RESULTS

In the four patients with active celiac disease but in none of the controls, CD25 was expressed by both duodenal and rectal lamina propria cells and HLADR was expressed by duodenal (4/4) and rectal (2/4) epithelial cells. In addition, two patients with active celiac disease had features of lymphocytic colitis, i.e., >20 IEL per 100 epithelial cells. After a gluten-free diet, the mean number of rectal CD3+ betaF1+ IEL decreased (9% vs 21%) and the expression of CD25 and HLADR was no longer present. These changes mirrored those found in the small intestinal biopsies.

CONCLUSION

These results suggest that in celiac disease, gluten-driven T-cell activation is not restricted to the proximal part of the intestine but is present on the whole intestinal length. Assessment of the effectiveness of a gluten-free diet through rectal biopsies warrants investigation, as it could lessen discomfort for patients and prove more cost-effective.

Esophageal impairment in adult celiac disease with steatorrhea

OBJECTIVE

A high prevalence of reflux esophagitis in celiac children and gut motor disorders in adult patients have been described. The aim of this study is to investigate the prevalence of esophageal symptoms and the esophageal motility pattern in adult celiac patients before and after gluten-free diet.

METHODS

In 22 consecutive adult celiac patients, before and after gluten-free diet, and in controls we calculated an esophageal symptom score regarding heartburn, regurgitation, dysphagia, and chest pain, and performed esophageal manometry using a constantly perfused multilumen catheter.

RESULTS

Patients were divided into two groups: with and without steatorrhea. Before gluten-free diet, the prevalence of esophageal symptoms was 45.5 % in all patients, but was significantly higher in patients with steatorrhea than in those without and in 44 control subjects (80% vs 16.7% and 27%, p < 0.05). Lower esophageal sphincter pressure was 17.5+/-5.3 in all patients, but was significantly lower in patients with steatorrhea than in patients without steatorrhea and 11 controls subjects (13.1+/-4.1 vs 21.0+/-2.9 and 20.7+/-3.7 mm Hg (mean+/-SD, p < 0.05). After the diet, the prevalence of esophageal symptoms diminished in all patients (9% vs 45.4%, p < 0.05) and lower esophageal sphincter pressure, measured in 13 patients, increased (19.0+/-3.7 vs 15.7+/-5.3 mm Hg, p < 0.05).

CONCLUSION

Adult celiac patients with steatorrhea present a higher prevalence of esophageal symptoms and a lowered lower esophageal sphincter pressure compared with celiac patients without steatorrhea and control subjects, but these phenomena can be reverted to control levels by gluten-free diet.

Gluten sensitivity in patients with primary biliary cirrhosis

OBJECTIVE

Whereas celiac disease and primary biliary cirrhosis have been reported to coexist in the same patient, the frequency of this relationship has not been clarified. Nowadays, the concept of celiac disease has been extended from that of a severe enteropathy to a broader concept of gluten-driven intestinal immunological response. In this study we assessed features of gluten sensitivity in a cohort of patients with primary biliary cirrhosis.

METHODS

Ten patients with primary biliary cirrhosis were evaluated a mean of 2 yr after diagnosis. The following features of gluten sensitivity were assessed: serum antigliadin and endomysial antibodies, small bowel histology (degree of atrophy and quantitative histological parameters), the presence of the typical celiac HLA genotype (DQ2), and intraepithelial lymphocyte response in the rectal mucosa after local gluten instillation (rectal gluten challenge).

RESULTS

Overall, three patients presented evidence of gluten sensitivity. All three had abnormal titers of antigliadin antibody type IgA and one was positive for endomysial antibody. Two patients had partial villous atrophy. The rectal gluten challenge showed a celiac-like response, evidenced by an increase in intraepithelial lymphocyte infiltration after gluten exposure, in the three patients. The characteristic celiac HLA genotypes (DQA1 0501 and DQB1 0201) were identified in three patients. One of them also exhibited other features of gluten sensitivity. However, despite evidence of gluten intolerance, patients had minimal or no symptoms characteristic of celiac disease.

CONCLUSION

We detected features of gluten sensitivity in a high proportion of patients with primary biliary cirrhosis. Further studies should be performed to elucidate the clinical significance of this association.

T-cell responses and cellular immunity in coeliac disease

Increasing evidence points to a direct role for T cells in the mediation of the coeliac intestinal lesion. There is good evidence for increased local T-cell reactivity, manifest as increased in T-cell activation in the lamina propria and T-cell proliferation in the epithelial compartment. A likely scenario is that gluten elicits antigen-specific responses by lamina propria T helper cells, probably of the Th1 (inflammatory-mediator) subtype, leading to secretion of pro-inflammatory cytokines. Such cytokines may have direct effects on intestinal enterocytes, as well as mediating indirect effects by upregulation of MHC antigens and by enhancing the activity of cytolytic T cells. Although gluten-specific IEL responses have not been demonstrated by intraepithelial T lymphocytes (IELs), increasing evidence suggests that IELs can act as cytolytic effector cells and hence are likely to exert enteropathic effects under the influence of pro-inflammatory cytokines.

Failure of intradermal skin testing with gluten to produce delayed hypersensitivity reactions in patients with dermatitis herpetiformis

Dermatitis herpetiformis (DH) is characterized by a rash and a gluten-sensitive enteropathy (GSE) indistinguishable from that of coeliac disease. T-cell-mediated mechanisms have been implicated in the pathogenesis of GSE. It seems feasible that intradermal injection of gluten, in patients known to have GSE, could lead to an influx of T cells sensitized to gluten, with subsequent development of a delayed hypersensitivity-type reaction. Six patients with DH and three normal subjects had intradermal injections of 'Frazer's fraction III' (FFIII; the partial peptic tryptic digest of gluten which is known to be antigenic) and phosphate-buffered saline (PBS) as a control. Skin biopsies were taken at PBS and FFIII injection sites at 48 h. In addition, two of the patients with DH had biopsies taken of FFIII injection sites at 6 h. Monoclonal antibodies and the avidin-biotin-peroxidase technique were used to stain for T cells in the skin biopsies. A monoclonal antibody to a neoepitope exposed in the terminal complement complex and an immunofluorescent method were used to detect the presence of terminal complement component in biopsies taken from two of the control subjects and two of the patients. Both patients and control subjects developed a weal and flare within a few minutes of injecting the FFIII, and this persisted for up to 6 h. No skin reaction was present in either the patients or the control subjects at 48 h. No skin reaction was visible at any time following injection of PBS.(ABSTRACT TRUNCATED AT 250 WORDS)

Morphometric analysis of intestinal mucosa. V. Quantitative histological and immunocytochemical studies of rectal mucosae in gluten sensitivity

To study changes in rectal mucosa that might be attributable to the effects of gluten, rectal biopsy specimens from untreated and treated gluten sensitised subjects were analysed morphometrically and by immunohistochemical techniques and were compared with a series of disease control mucosae. Although morphometry showed increased populations of plasma cells, lymphocytes, and mast cells in the mucosae of untreated patients, which were reduced (except for mast cells) by dietary gluten restriction, immunohistochemical techniques were far more sensitive in defining these changes. There were highly significant increases in CD3+ and gamma delta+ lymphocytes within both the lamina propria and the epithelium while neutrophils (CD15+ cells) were not at all prominent. Activated (CD25+) lymphocytes expressing interleukin (IL)-2 receptors were increased in lamina propria, usually subjacent to basal lamina, although a few IL-2R+ intraepithelial lymphocytes were found: other IL-2R+ cells were deemed to be macrophages (CD68+). These results clearly indicate that in untreated, gluten sensitised subjects the rectal mucosa shows a lymphoplasmacytoid reaction that is responsive to gluten restriction. The absence of neutrophilia suggests that this lesion is not a conventional inflammatory type proctitis, but rather one presumed to be induced by gluten antigen(s) present in the faecal stream--that is, a cell mediated form of response.

Rectal epithelial gamma/delta T-lymphocyte responses to local gluten challenge in coeliac disease

The proportion of intra-epithelial lymphocytes (IEL) that utilize the gamma/delta form of the T-cell receptor (TCR) is increased in coeliac disease, but their function remains unexplained. The response of intra-epithelial lymphocytes to rectal gluten challenge in coeliac and control subjects was studied after a rectal challenge of 2 g of Frazer's fraction III. A marked rise in CD3+ IEL occurred after challenge in the coeliac patients, peaking at 6 h and returning to normal by 48 h, with no significant changes in the gamma/delta TCR+ IEL. The IEL did not significantly change after gluten challenge in the controls. Acute gluten challenge induces infiltration of the rectal mucosa by T cells in coeliac patients, which is not accompanied acutely by increased numbers of gamma/delta TCR+ IEL. This study supports the hypothesis that alpha/beta TCR+ T cells may be of importance in the early response of coeliac patients to local gluten challenge.

Management of coeliac disease: a changing diagnostic approach but what value in follow up?

OBJECTIVE

To assess the management of patients with coeliac disease in relation to a change in diagnostic method from jejunal suction biopsy to endoscopic biopsy.

DESIGN

16 item questionnaire survey of consultant members of the British Society of Gastroenterology.

SUBJECTS

359 consultant physician and gastroenterologist members of the society.

MAIN MEASURES

Type of routine biopsy; repeat biopsy after gluten withdrawal; gluten rechallenge; follow up measurements; screening for malignancy; and methods of follow up, including special clinics.

RESULTS

270(70%) members replied; 216(80%) diagnosed coeliac disease routinely by endoscopic duodenal biopsy, 30(11%) by jejunal capsule biopsy, and the remainder by either method. Only 156(58%) repeated the biopsy after gluten withdrawal, though more did so for duodenal than jejunal biopsies (134/216, 62% v 13/30, 43%; p < 0.02). Follow up biopsies featured more duodenal than jejunal biopsies (133/156, 82% v 23/156, 15%; p < 0.02). Regular follow up included assessments of weight (259, 96%) and full blood count (238, 88%) but limited assessment of serum B-12 and folate (120, 44%) and calcium (105, 39%) concentrations. Routine screening for malignancy is not performed, and there are few specialist clinics. 171(63%) respondents thought that patients should be followed up by a hospital specialist and 58(21%) by family doctors.

CONCLUSIONS

The practice of diagnosing coeliac disease varies appreciably from that in many standard texts. Many patients could be effectively cared for by their family doctor.

IMPLICATIONS

The British Society of Gastroenterology should support such management by family doctors by providing clear guidelines for them.

Gamma/delta T cells and the diagnosis of coeliac disease

Gamma/delta T cells are increased in the gut epithelium of patients with coeliac disease compared with normal controls. The aim of this study was to determine whether the increase in gamma delta intraepithelial lymphocytes (IEL) is specific for coeliac disease, in which case it could be of diagnostic importance. Biopsies were obtained from children with no intestinal disease, coeliac disease, cow-milk-sensitive enteropathy/post-enteritis syndrome (CMSE PES) and miscellaneous other enteropathies (n = 67). Intraepithelial CD3+ and gamma delta T cells were identified in frozen sections using peroxidase immunohistochemistry. In normal biopsies there were 0-7 gamma delta IEL/100 cells in the epithelium. In untreated coeliac patients this increased to 9-22 gamma delta IEL/100 cells in the epithelium (P = 0.000004). Of 27 patients with morphologic intestinal damage which was not due to coeliac disease, four with CMSE/PES had gamma delta IEL/100 cells in the epithelium in the same range as the patients with coeliac disease. Of these, two had high densities of CD3+ IEL in the epithelium and were indistinguishable from patients with untreated coeliac disease. The other two could be excluded as possible coeliacs because their CD3+ IEL/100 epithelial cells were in the normal range. Thus an increase in gamma delta IEL is not specific for coeliac disease. However, enumeration of both of gamma delta IEL and CD3+ IEL densities will be useful in the exclusion of coeliac disease as a diagnosis in some children.

Is schizophrenia caused by excessive production of interleukin-2 and interleukin-2 receptors by gastrointestinal lymphocytes?

Excessive production of interleukin-2 (IL-2) and IL-2 receptors (IL-2R) by gastrointestinal (GI) T-lymphocytes is hypothesized as the cause of schizophrenia. It is based on: 1) IL-2 given to human volunteers can cause all the symptoms of schizophrenia; 2) GI lymphocytes in nonhuman primates produce much more IL-2 and IL-2R when stimulated than peripheral blood lymphocytes; 3) the GI tract is the largest lymphoid 'organ' in the body. The hypothesis appears to: 1) explain the protective effect of rheumatoid arthritis on schizophrenia; 2) make mechanistically plausible the findings on wheat and schizophrenia; 3) be consistent with and explain many of the known immunological abnormalities in schizophrenia.