Studies of intestinal lymphoid tissue. VI--Proliferative response of small intestinal epithelial lymphocytes distinguishes gluten- from non-gluten-induced enteropathy

Celiac disease: mechanisms and emerging therapeutics

Celiac disease (CeD) is a widespread, gluten-induced, autoimmune disorder that lacks any medicinal therapy. Towards the goal of developing non-dietary treatments for CeD, research has focused on elucidating its molecular and cellular etiology. A model of pathogenesis has emerged centered on interactions between three molecular families: specific class II MHC proteins on antigen-presenting cells (APCs), deamidated gluten-derived peptides, and T cell receptors (TCRs) on inflammatory CD4+ T cells. Growing evidence suggests that this pathogenic axis can be pharmacologically targeted to protect patients from some of the adverse effects of dietary gluten. Further studies have revealed the existence of additional host and environmental contributors to disease initiation and tissue damage. This review summarizes our current understanding of CeD pathogenesis and how it is being harnessed for therapeutic design and development.

Coeliac disease: factors affecting the transition and a practical tool for the transition to adult healthcare

Background

As of now, no established model for the transition from childhood to adulthood in coeliac disease exists. We aim to describe the dietary compliance and the quality of life of a population of young coeliac disease patients around transition age and to develop a practical tool (TRANSIT-CeD disk) which can be used during the transition process effectively to transmit young adults to the adult healthcare giver.

Methods

We consecutively recruited all coeliac disease patients with a paediatric diagnosis (≤16 years) and aged between 9 and 20 years at the time of the study. The patients were asked to answer some questions concerning their adherence to a gluten-free diet, knowledge about coeliac disease, relationship with healthcare givers and quality of life.

Results

We included 58 subjects, mean age 14.5 ± 3.6 years, of which 62% were girls/young women. We observed that dietary compliance was independently and positively related to age at diagnosis and coeliac disease knowledge, while quality of life was only independently and positively related to coeliac disease knowledge.

Conclusion

A good coeliac disease knowledge is positively related to dietary compliance and quality of life. With the help of the TRANSIT-CeD disk we proposed, paediatricians and adult gastroenterologists can follow the patients during the transition and identify some points to work on.

Evolutionary Developments in Interpreting the Gluten-Induced Mucosal Celiac Lesion: An Archimedian Heuristic

The evolving history of the small intestinal biopsy and its interpretation—and misinterpretations—are described in this paper. Certain interpretative errors in the technical approaches to histological assessment are highlighted—even though we may never be rid of them. For example, mucosal “flattening” does not reduce individual villi to their cores, as still seems to be widely believed. Neither is the mucosa undergoing an atrophic process—since it can recover structurally. Rather, the intestinal mucosa manifests a vast hypertrophic response resulting in the formation of large plateaus formed from partially reduced villi and their amalgamation with the now increased height and width of the inter-villous ridges: this is associated with considerable increases in crypt volumes. Sections through mosaic plateaus gives an erroneous impression of the presence of stunted, flat-topped villi which continues to encourage both the continued use of irrelevant “atrophy” terminologies and a marked failure to perceive what random sections through mosaic plateaus actually look like. While reviewing the extensive 40+ year literature on mucosal analysis, we extracted data on intraepithelial lymphocytes (IEL) counts from 607 biopsies, and applied receiver-operating characteristic (ROC)-curve analysis. From that perspective, it appears that counting IEL/100 enterocyte nuclei in routine haematoxylin and eosin (H&E) sections provides the most useful discriminator of celiac mucosae at histological level, with an effective cut-off of 27 IEL, and offering a very high sensitivity with few false negatives. ROC-curve analysis also revealed the somewhat lesser accuracies of either CD3⁺ or γδ⁺ IEL counts. Current official guidelines seem to be somewhat inadequate in clearly defining the spectrum of gluten-induced mucosal pathologies and how they could be optimally interpreted, as well as in promoting the ideal manner for physicians and pathologists to interact in interpreting intestinal mucosae submitted for analysis. Future trends should incorporate 3-D printing and computerised modelling in order to exemplify the subtle micro-anatomical features associated with the crypt-villus interzone. The latter needs precise delineation with use of mRNA in-section assays for brush border enzymes such as alkaline phosphate and esterase. Other additional approaches are needed to facilitate recognition and interpretation of the features of this important inter-zone, such as wells, basins and hypertrophic alterations in the size of inter-villous ridges. The 3-D computerised models could considerably expand our understandings of the microvasculature and its changes—in relation both to crypt hypertrophy, in addition to the partial attrition and subsequent regrowth of villi from the inter-villous ridges during the flattening and recovery processes, respectively.

Effects of X-rays and cigarette smoking on leukocyte, lymphocyte and mitotic index values and SCE rates: the relationship between mitotic index and lymphocyte count

Many previous studies revealed that smoking increases leukocyte and lymphocyte counts while exposure to X-rays decreases these counts. However the relationships between lymphocyte life span and smoking as well as X-rays were not well documented. The primary aim of this study was to determine relationships between smoking X-rays (in combination and individually) and life span of lymphocytes. Blood samples from 200 healthy individuals, half of which were X-ray exposed individuals, were collected. Half of X-ray exposed and of non-X-ray exposed individuals were smokers. There were equal numbers of male and female participants. Two lymphocyte cultures, one for the sister chromatid exchange (SCE) analysis and the other for the determination of mitotic index values were prepared using one part of the blood samples collected from the individuals. From the other part of the blood sample leukocyte and lymphocyte counts were determined with a haemogram device. Evaluation of the findings suggested that leukocyte count, lymphocyte count, mitotic index were relatively lower for the X-ray exposed individuals. In addition these values were higher for smokers than nonsmokers in general. The highest SCE rates were recorded for smoking radiology technicians. The most important finding is that lymphocyte life span is relatively low in smokers and in X-ray exposed males.

Small intestinal mucosal immunity and morphometry in luminal overgrowth of indigenous gut flora

OBJECTIVE

The aim of this study was to investigate the separate effects of indigenous oropharyngeal- and colonic-type flora on small intestinal mucosal immunity and morphometry in small intestinal bacterial overgrowth (SIBO).

METHODS

A duodenal aspirate and random biopsies of underlying mucosa were obtained from 52 adult subjects (age range, 18-90 yr; median, 60 yr) without disorders that may otherwise disturb small intestinal histology or mucosal immunity. Villus height, crypt depth, villus/crypt ratios, counts of intraepithelial lymphocytes (IELs) and lamina propria total mononuclear cells, IgA, IgM, and IgG plasma cells, mast cells, and B and T lymphocytes were determined in relation to the presence or absence of SIBO and the nature of the overgrowth flora in all subjects. CD4+ve and CD8+ve T-cell counts were determined in 24 subjects.

RESULTS

SIBO was present in 26 of 52 (50%) subjects. Overgrowth flora included colonic-type bacteria in 20 subjects and oropharyngeal-type flora alone in 6 subjects. Lamina propria IgA plasma cell counts were significantly increased in subjects with SIBO, irrespective of whether the overgrowth flora comprised oropharyngeal-type flora alone or included colonic-type bacteria. Neither villus height, crypt depth, villus/crypt ratios, nor total or other mononuclear cell counts in lamina propria differed significantly between subjects with and without SIBO, irrespective of the nature of the overgrowth flora. IEL counts were significantly higher than in culture-negative subjects only when the overgrowth flora included colonic-type bacteria. Even then, IEL counts were within a range currently considered normal. A significant, inverse correlation between advancing age and IEL counts became apparent after adjusting for the effect of SIBO of colonic-type flora.

CONCLUSIONS

SIBO of oropharyngeal- and colonic-type flora are associated with differing disturbances of local duodenal mucosa. Nonetheless, these would not be readily apparent during routine histological assessment. Old age independently influences duodenal IEL counts.

Luminal bacteria and small-intestinal permeability

BACKGROUND

The influence of luminal bacteria on small-intestinal permeability has not been fully assessed. This study addressed this issue.

METHODS

Thirty-four subjects (mean age 64 years; range 22-95 years) were investigated for possible small-intestinal bacterial overgrowth (SIBO) with culture of a small-intestinal aspirate. A lactulose/mannitol small-intestinal permeability test was performed, small-intestinal histology assessed and serum vitamin B12 concentrations measured in all subjects. Permeability was also assessed in a control group of 34 asymptomatic volunteers.

RESULTS

Urinary lactulose/mannitol ratios were significantly increased in subjects with SIBO with colonic-type flora (P < 0.0005), even in the absence of villous atrophy. Urinary lactulose/mannitol ratios were increased in this group due to significantly increased urinary lactulose concentrations (P < 0.0005) rather than reduced urinary mannitol levels, after correcting for inter-subject variations in renal function. Counts of intraepithelial lymphocytes of CD8 phenotype were significantly increased in this group (P = 0.003). Although a significant correlation was found between intraepithelial lymphocyte counts and small-intestinal permeability overall (P < 0.002), these counts were not significantly different in subjects with SIBO with colonic-type flora whose permeability values were < or = > 0.028, the upper limit of normal in asymptomatic controls. Serum vitamin B12 concentrations did not differ significantly between groups (P > 0.5). Ageing did not independently influence small-intestinal permeability (P > 0.5).

CONCLUSIONS

Small-intestinal permeability is increased in subjects with SIBO with colonic-type bacteria. This effect is independent of ageing and not mediated by vitamin B12 deficiency. Although counts of intraepithelial lymphocytes of CD8 phenotype are increased in this disorder, it is also unlikely that these cells play an important causative role in this process. Routine light microscopic assessment underestimates the prevalence of small-intestinal functional disturbance in this disorder.

Non-Hodgkin's lymphoma, coeliac disease, and Epstein-Barr virus: a study of 13 cases of enteropathy-associated T- and B-cell lymphoma

A group of 166 patients with coeliac disease was followed for a period of up to 25 years. During this time, 17 patients developed intestinal tumours that were diagnosed as lymphoma, of which 15 cases were available for review. Eleven of the lymphomas were of T-cell type (enteropathy-associated T-cell lymphoma, EATL) and two were of B-cell type. Two cases were reclassified as undifferentiated carcinoma. The interval between the diagnosis of enteropathy and the onset of lymphoma varied from less than 2 months in four patients to more than 5 years in seven. Seven of the T-cell and both B-cell lymphomas were investigated for the presence of Epstein-Barr virus (EBV) by in situ hybridization (ISH) using probes against Epstein-Barr virus-encoded RNAs (EBERs) and by immunohistochemistry with EBV-specific monoclonal antibodies. All EATL cases were negative, suggesting that EBV is not an important factor in these cases. In one of the B-cell cases, EBV was detectable by ISH and immunohistochemistry in most tumour cells in the mesenteric lymph nodes, but not in any of the tumour cells in the primary ileal tumour, indicating that in this case EBV infection was a late event in the neoplastic process. These results show that lymphoma may develop any time after the onset of coeliac disease and that in our cases of EATL, EBV was not an important factor. In some cases of EBV-related neoplasia, virus infection may be a late event.

Morphology of the mucosal lesion in gluten sensitivity

Gluten sensitivity is associated with a spectrum of mucosal lesions, arbitrarily termed pre-infiltrative, infiltrative-hyperplastic, flat-destructive and atrophic-hypoplastic. Histologically and immunohistologically these lesions are all compatible with T-cell-driven events operative at a local mucosal level. They are classifiable either in terms of antibody titres (pre-infiltrative) (see Chapter 10) or by the characteristic disposition of IELs throughout the surface and crypt epithelium. From in-vivo challenges, it has been demonstrated: (i) that all these lesions comprise a dynamically interrelated series of events, culminating in the severe flat-destructive lesion; and (ii) that gluten evokes a dose-responsive infiltration of IELs (CD3+ CD8+ and TCR alpha beta + or gamma delta +) into the epithelium. Apart from that, little is known of the functions of IELs; it is possible they may have little to do with the evolving mucosal pathology of gluten sensitivity. Increasing work seems to support a view, proposed from this laboratory over 10 years ago, that the immune-mediated responses in jejunal tissue in gluten sensitivity arise in the lamina propria, in association with DR+ macrophages and an abundance of CD4(+)-activated lymphocytes. Many other inflammatory consequences flow from these interactions, involving activation of mast cells, eosinophils and neutrophils, elaboration of cytokines and other products of inflammation, and increased hyperpermeability of the microvasculature with upregulation of adhesion molecules. The result is a doubling of lamina propria volumes in the severe flat lesion. Evidence is also given to show that measurable changes in lamina propria inflammation occur with the infiltrative-hyperplastic lesion. Symptomatology is not related to the degree of proximal mucosal pathology, but to the extent of the mucosal lesion. Data, although scanty, suggests that lesional pathology involves only 30-50% of the entire small bowel mucosa. Thus, most patients, irrespective of proximal mucosal damage, have latent (or asymptomatic) gluten sensitivity. Symptom development requires additional environmental triggers, of which infection is a major contributor. It should also be noted that, while these various environmental triggers may precipitate symptomatology, they do not advance the severity of the mucosal lesion.

Screening for antibodies against gliadin in patients with osteoporosis

Intestinal disease might contribute to osteopenia. Measurements of IgA antibodies to gliadin have been established as an accepted screening procedure for detection of coeliac disease. When we applied these measurements to 92 patients with verified osteoporosis, 11 subjects (12%) were found to have elevated levels. This is markedly higher than the incidence in healthy subjects (3%). However, the patients with raised levels of IgA antibodies displayed no clinical symptoms and no laboratory evidence of calcium malabsorption. Thus their values for serum calcium, phosphate, parathyroid hormone (PTH), alkaline phosphatase and osteocalcin, as well as the fasting urinary excretion of hydroxyproline and calcium, were similar to those found in other patients with osteoporosis. Intestinal biopsy verified coeliac disease in three patients and was normal in another three. This gives an incidence of verified coeliac disease in this patient group that is approximately tenfold higher than that in the healthy population. Subclinical coeliac disease appears to be unusually over-represented among patients with idiopathic osteoporosis, and screening for gliadin antibodies might therefore be a valuable addition to the routine assessment of the osteopenic patient. The mechanisms underlying the relationship are not clear, but calcium malabsorption is not evident.

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 adult-onset coeliac disease due to a low-grade lymphoma of intraepithelial T lymphocytes?

Enteropathy-associated T-cell lymphoma commonly presents with malabsorption, and debate continues as to whether adult-onset coeliac disease (CD) is itself a form of low-grade lymphoma. A 59-year-old man with adult-onset CD required resection of a segment of oedematous jejunum. Histological examination of this tissue revealed an intense intraepithelial lymphocytosis. Immunophenotypic (CD3-, CD4-, CD8-, CD34-, and CD45 RO-) and cytogenetic (deletion of the Y chromosome and chromosome 9) abnormalities were found, together with monoclonal T-cell-receptor gene rearrangements. Some patients with adult-onset CD may have low-grade lymphoma from the outset of their illness.

Morphometric studies in duodenal biopsies from patients with coeliac disease: the effect of the steroid fluticasone propionate

Morphometric measurements have been performed on small intestinal biopsy specimens from patients with untreated coeliac disease before and after six weeks oral treatment with a steroid of low systemic bioavailability (fluticasone propionate). Measurements were obtained by point counting and also by a computer-aided measuring system with reference to a constant area of the muscularis mucosa. Fluticasone propionate led to a parallel reduction in the intraepithelial lymphocyte count within the surface (P less than 0.001) and crypt epithelium (P less than 0.01). The intra-epithelial lymphocyte count assessed by reference to constant areas of the muscularis mucosa and surface epithelium were decreased two-fold (P less than 0.01) and seven-fold (P less than 0.001) respectively. Fluticasone propionate treatment also led to significant increases in the absorptive surface epithelium as shown by an increase in the villus:crypt ratio (P less than 0.01), the epithelial cell height (P less than 0.01) and two- to three-fold increases in the area and length of the surface epithelium (P less than 0.001). Short-term fluticasone propionate treatment appears to exert a powerful beneficial effect upon duodenal morphology in patients with coeliac disease. Whether the alterations seen are comparable to a similar period of gluten withdrawal is not yet known.

Signs of increased leakage over the jejunal mucosa during gliadin challenge of patients with coeliac disease

Intestinal secretion rates of albumin, hyaluronan, and beta 2-microglobulin (beta 2-micro) were determined under basal conditions and after gliadin challenge of coeliac patients and healthy controls by the use of a jejunal perfusion technique. A new tube system was used where a jejunal segment is isolated between balloons and then perfused with a balanced salt solution. Under basal conditions the secretion rate of albumin was similar in the patients and controls while the secretion rate of the glycosaminoglycan hyaluronan, a high molecular weight connective tissue component, was increased more than two times in coeliac patients. Beta 2-micro was secreted in on average three-fold rates in coeliacs compared with controls. All three substances were secreted at a higher rate in patients with active disease than in those with inactive disease defined by morphological damage in small bowel biopsies. The concentrations in jejunal perfusion fluids relative to serum levels in the coeliac patients were for albumin 0.0007, beta 2-micro 0.10, and for hyaluronan 1.94. Challenge with a single dose of gliadin into the jejunal segment gave within 60 min a significant, about two-fold, increase of the secretion rates of all three measured substances. The appearance of hyaluronan could reflect a gliadin induced mucosal oedema with an enhanced leakage from the interstitial/lymph fluid, rich in this glycosaminoglycan. The observed parallel increases in the jejunal secretion of albumin and beta 2-micro after gliadin challenge are best explained by a similar mechanism.

Studies of intestinal lymphoid tissue. XV. Histopathologic features suggestive of cell-mediated reactivity in jejunal mucosae of patients with dermatitis herpetiformis

Peroral jejunal mucosae from 32 patients with untreated DH were quantitated by computerized image-analysis in terms of surface (villous) and crypt epithelial volumes and their corresponding lymphoid infiltrates, together with lamina propria volumes, neutrophils, mast cells and basophils. Three distinctive patterns of mucosal abnormality were identified: (a) the "infiltrative" lesion in which normal villus epithelium was infiltrated by small, non-mitotic lymphocytes: (b) the "hyperplastic" type, in which crypt hyperplasia and hypertrophy together with lymphoid infiltration of crypt epithelium was additional to the "infiltrative" lesion, and in which lamina propria was swollen and contained modest neutrophilic and basophilic infiltration: and (c) the "destructive" lesion, identical to the classic celiac sprue appearances with effacement of villi, crypt hypertrophy and more intensive polymorph infiltration of lamina propria. These progressive lesions parallel those seen in experimental graft-versus-host reactions, so that the entire spectrum of changes described here in DH appear consistent with a cell-mediated mucosal response to gluten. The extent of mucosal abnormality was unrelated to individual HLA status.

The immunopathology of the small intestinal reaction in gluten-sensitivity

Computerised image-analysis was used to define the spectrum of immunopathological changes in small intestinal mucosa in established celiac sprue disease; dermatitis herpetiformis; 1 degree relatives of celiac sprue patients, and treated celiac sprue patients challenged with varying doses of a peptic-tryptic digest of gluten. Typically, in flat ('Type 2') lesion there was a reduced number of large, mitotically active lymphocytes in surface epithelium, but an increased lymphocyte population in crypts. In approximately 50% untreated DH patients and in 20% 1 degree celiac sprue relatives, mucosal architecture was well-preserved although surface (villous) epithelium contained an expanded population of small, non-mitotic lymphocytes ('Type 1' lesion), with or without crypt hyperplasia. Similar changes were also induced by small dose gluten challenge. Larger dose challenges caused a progression from a Type 1 to a Type 2 lesion during a 5 day period of observation. In addition, observations on a few patients over 2-4 years showed a similar sequence of mucosal changes. A major feature of this sequence was the early appearance of crypt hypertrophy, before significant villous flattening had occurred. These changes parallel T lymphocyte-mediated graft- versus-host reactions in animals, suggesting that the specific immunopathologic features seen in gluten sensitivity are fundamentally cell-mediated in type, the degree of change probably dependent on host genetic factors. Finally, these data show that in becoming flat the mucosa must initially pass through the earlier Type 1 lesion in which crypt hypertrophy is a prominent response.

Studies of intestinal lymphoid tissue. X-observations on granular epithelial lymphocytes (gEL) in normal and diseased human jejunum

A proportion of epithelial lymphocytes in various mammalian species is characterised by cells containing cytoplasmic granules. We have studied the total number of granular lymphocytes within surface and crypt epithelium of jejunal mucosae (per 10(4) micron2 muscularis mucosae) from six groups of subjects, comprising (i) young healthy volunteers (ii) family relatives of known coeliac patients, patients with gastrointestinal disorders associated with either (iii) normal or (iv) "flat" mucosae, and groups of (v) untreated and (vi) treated patients with coeliac disease. There was no difference in the absolute number of gEL between the three control groups with normal mucosal architecture, the proportion of granular to total EL per unit of tissue varying between 30-40%. In untreated coeliac mucosae, there was a significantly increased population of gEL, compared with the same control groups (p less than 0.001): the ratio of granular to total EL approximated 65%, and did not differ from flat-control mucosae in which the proportion of gEL was 55%. On withdrawal of gluten, the absolute number of gEL fell significantly in comparison with the untreated coeliac group (p less than 0.05). To further evaluate the effect of gluten challenge, granular lymphocytes were monitored during a five-day period in groups of treated coeliac patients orally challenged with increasing doses (500-3000 mg) of a peptic-tryptic digest of gluten. A significant rise in the absolute number of granular lymphocytes occurred at 12 h, but without any deterioration in mucosal architecture.

Gut endocrine cell population in coeliac disease estimated by immunocytochemistry using a monoclonal antibody to chromogranin

Abnormalities of gut endocrine responses, as well as changes in the number of different endocrine cell types, have been reported convincingly in coeliac patients. Nevertheless, no estimation of total numbers of gut endocrine cells has yet been made in well defined groups of coeliacs. In this study, we have visualised all endocrine cell types in jejunal biopsies from coeliac patients with active and quiescent disease as well as in controls, using a monoclonal antibody to chromogranin. This protein was purified originally from bovine adrenal medulla and is known to be a reliable marker for all endocrine cells of the gut. The following groups were considered: (a) nine coeliacs with active illness, (b) 10 coeliacs under gluten-free diet, (c) eight coeliacs receiving gluten challenge, (d) five non-coeliacs (controls). Histological (haematoxylin and eosin) and immunocytochemical (peroxidase anti-peroxidase) stains were applied to 3 micron paraffin sections. Quantitative estimation of endocrine cell density was made using four different methods in order to evaluate the results fully (number of cells/mm2, number of cells/visual field, number of cells/8 crypts-villi, number of cells/unit of length of muscularis mucosae). In patient groups (a) and (c), coeliacs with active disease and coeliacs on gluten challenge diet respectively, a significantly higher number of endocrine cells was observed in comparison with normal controls (group d). In group (b) patients, coeliacs on gluten-free diet, no significant changes in the number of endocrine cells were observed in comparison with controls. Our results show that a significant increase in endocrine cell density exists in coeliacs with active illness (groups a and c), in comparison with controls. This condition is resolved in coeliacs receiving a gluten-free diet (group b).

Serum IgG subclass antibodies to gliadin and other dietary antigens in children with coeliac disease

IgG subclasses of antibodies to the dietary antigens gliadin, glycgli (a gluten component), ovalbumin (OA) and beta-lactoglobulin (BLG) were quantified in children with coeliac disease (CD), nine on a gluten-containing diet, 15 on a gluten-free diet, and in appropriate controls. In addition, total serum IgG subclasses were measured. IgG1 and IgG3 antibodies to gluten and glycgli were detected in 9/9 and 8/9 CD-patient on a gluten-containing diet, respectively, and in 4/15 and 6/15 patients on a gluten-free diet. None of the controls had appreciable levels of IgG1 antibodies and only 1/22 of the controls had IgG3 antibodies to gliadin and glycgli. IgG2 and IgG4 antibodies to the same antigens were found in a few coeliacs and controls. Consecutive samples from coeliac children (8 patients) showed a clear relation between the exposure to gluten and a rise in IgG1 (8/8) and IgG3 antibody levels (7/8). In contrast, IgG antibodies to OA and BLG were almost exclusively of the IgG1 and IgG4 subclasses. The highest levels were found in children with CD, but the differences between the groups were not significant. Total serum IgG subclasses did not differ between the groups, but the IgG2 and IgG4 levels in most coeliac children were low. The production of IgG1 and IgG3 antibodies to gluten components may be an important precondition for the development of coeliac disease in susceptible individuals.

Intraepithelial lymphocyte mitosis in a jejunal biopsy correlates with intraepithelial lymphocyte count, irrespective of diagnosis

When there is villus atrophy in a jejunal biopsy, intraepithelial lymphocyte (IEL) mitosis correlates with a diagnosis of coeliac disease. We have examined the significance of IEL mitosis in jejunal biopsies with normal villi. Counts of IEL per 100 villus enterocytes, and IEL mitosis per 1000 IEL, were carried out in 81 jejunal biopsies. Thirty one were from patients with coeliac disease or dermatitis herpetiformis, and many of these, from treated patients, were histologically normal; 40 were from patients with other diagnoses, selected to include biopsies with a high IEL count (greater than 40 IEL per 100 enterocytes) but normal villi. Three coeliacs and 10 dermatitis herpetiformis patients had an IEL count of less than 40, and no IEL mitoses were found in these biopsies. Two dermatitis herpetiformis patients had IEL counts of 43.7% and 43.9%, with no IEL mitoses, but in all other coeliac and dermatitis herpetiformis biopsies high IEL counts were associated with IEL mitotic indices between 0.05% and 1.77%. In the non-coeliac, non-dermatitis herpetiformis group, no IEL mitoses were found in the 22 biopsies with IEL count less than 43%. In the others, IEL counts ranged from 44.8% to 127.0%, and IEL mitoses were present, with mitotic indices ranging from 0.06% to 0.49%. This work shows that IEL mitosis in a jejunal biopsy is not specific for coeliac disease, but occurs whenever there is an increased density of IEL within the villus epithelium.

Morphometric analysis of small intestinal mucosa. III. The quantitation of crypt epithelial volumes and lymphoid cell infiltrates, with reference to celiac sprue mucosae

With the aid of computerised image-analysis, morphometric techniques were used to measure the volumes of crypt epithelium, with reference to a constant test area (10(4) microns2) of muscularis mucosae, in untreated and treated celiac sprue mucosae in comparison with four other groups of control jejunal specimens. Crypt epithelial lymphocyte populations were also analyzed in terms of absolute numbers (N), mean nuclear (DN) and cytoplasmic (DCYT) diameters, and mean nuclear (VN) and cell (VCELL) volumes. Untreated celiac sprue crypts, despite a 3-5 fold increase in volume over control mucosae, contained a markedly expanded population of lymphocytes which was localised predominantly to the upper crypt regions and comprised approximately 6% large lymphocytes (DN greater than 6 microns: DCYT greater than 9 micron). These changes were entirely reversed by dietary treatment and hence were considered to be gluten-driven. The infiltrate might reflect the expression of gluten receptors on maturing upper crypt enterocytes: but why these lymphocytes do not cause any apparent injury to crypt epithelium (unlike surface epithelium) or influence its well-known compensatory response, remains unclear.

Functional and structural aspects of the epithelial lymphocyte, with implications for coeliac disease and tropical sprue

Epithelial lymphocytes comprise a compartmentalised and specialised population of presumed effector cells which, in general, express the surface phenotypes (Lyt-2+; OX2+; OKT8+) of suppressor/cytolytic (Ts/c) cells. Granular cells within this population (gEL) morphologically resemble the circulating large granular lymphocytes (LGL) which subserve spontaneous (NK) cytolytic activity. Recent in vitro results indicate that gEL can develop this function after prolonged in vitro culture; the relevance of this, in vivo, remains to be decided. EL also appear to be able to mediate ADCC with sIgA against enteric micro-organisms. This is the kind of integrated activity that might be anticipated from local immunocytes within the intestinal mucosa. Other recent work suggests that gEL are not precursors of mucosal mast cells. EL also appear to be capable of inducing Ia-like expression in surface and crypt enterocytes, a property enjoyed both by highly purified Th, but also Ts/c, cells as well. This raises the interesting prospect that enterocytes may display antigen in macrophage-like fashion to other adjacent cells within the inter-epithelial cell spaces. These latter observations might be more consistent with the presence of 'activated' and 'blast-transformed' lymphocytes in such conditions as coeliac disease and tropical sprue. Another emergent view that demands appropriate attention is that the infiltrate of Ts/c cells into surface, and crypt, epithelium of coeliac mucosa does not necessarily cause injury or damage to the jejunal tissues. Nevertheless the role, either primary or secondary, that EL play either in coeliac disease or tropical sprue still remains obscure.

[The gastrointestinal tract as an immunologic organ: the gut-associated immune system]

The gastrointestinal mucosa separates the intraluminal gastrointestinal fluid, which contains a high number of antigens from different sources, and prevents free access of antigens to the body. Simultaneously, it allows some vital host-environment interactions. A number of unspecific factors are important in preventing antigen invasion. The specific mucosal immunity is related to secretory IgA. IgA is derived from mucosal plasma cells after antigen-induced proliferation of its precursors in Peyer's patches. These IgA-positive B-lymphoblasts migrate through the systemic circulation and then "home" to the mucosa. IgA is translocated as a dimer to the gut lumen after attachment to the secretory component (SC). Part of it is excreted into the bile via small bile ducts after portal and possibly systemic circulation and binding to SC. T cells and mast cells are also considered to show migration and homing phenomena. In addition to the gut, some other mucosa-associated lymphoid tissues, (e.g. bronchus, mammary, salivary and lacrimal glands as well as the female genital tract), can participate in homing. Little is known about the local regulatory mechanisms, which allow an immunoglobulin class specifity of immune responses. Induction of local immunity and specific systemic tolerance seems to be a characteristic immune response of the gut-associated lymphoid tissue (GALT). The knowledge of the local immune system allows a better understanding of many aspects of gastrointestinal pathology, especially in immuno-inflammatory and immunoproliferative diseases as well as in gastrointestinal immunodeficiency syndromes.

Morphometric analysis of small intestinal mucosa. II. Determination of lamina propria volumes; plasma cell and neutrophil populations within control and coeliac disease mucosae

Morphometric techniques were employed to measure (i) lamina propria volumes and (ii) the absolute numbers of neutrophils and plasma cells, of A, M and G isotype, within the lamina propria of jejunal mucosa. Mucosal specimens were obtained with a Watson capsule (a) from 5 patients with untreated coeliac disease, and again at least 3 months after starting on a gluten-free diet, and (b) from 9 control individuals. Lamina propria volume of untreated coeliac mucosa (2.5 +/- 0.17 X 10(6) micron3 ) was increased 2.3-fold (p less than 0.01) above that of control mucosae (1.35 +/- 0.08 X 10(6) micron3 ). Compared with control mucosae, there was a 20-fold increase of neutrophils in untreated coeliac mucosae (p less than 0.005). The total complement of all plasma cells in untreated coeliac mucosae (309) was twice that (149) of control mucosae. The populations of each isotype were also significantly increased over controls by factors of 1.6 (IgA; p less than 0.05), 3.0 (IgM; p less than 0.01) and 3.5 (IgG; p less than 0.01). Their percentage distributions in untreated coeliac mucosae (A:M:G--52:43:5) differed from those in control mucosae (A:M:G--69:28:3) but were restored after treatment with a gluten-free diet. However, when each isotype was expressed per unit volume of lamina propria, there was an apparent fall (X 1.4) in IgA cells, while the increase in IgM and IgG cells was less marked i.e. X 1.4 and X 1.5 respectively. These precise measurements explain why many previous investigators found a paradoxical fall in IgA cells because the (increased) volume of distribution of these cells was not taken into account. The importance of morphometric techniques in achieving valid cell 'counts' within the intestinal mucosa is thus illustrated by this study.

Studies of intestinal lymphoid tissue. VII. The secondary nature of lymphoid cell "activation" in the jejunal lesion of tropical sprue

Morphometric techniques were used in the evaluation of lymphocyte morphology and activity in tropical sprue. jejunal biopsies from control subjects (8), patients with epidemic disease (7), patients with endemic disease (11), and subjects who had recovered from sprue (4) were analyzed blindly. In patients with sprue, lymphocytes were increased significantly within crypt (but not surface) epithelium. Immunoblasts (greater than 6 mu in diameter) were increased by 5% over control subjects. Group means for lymphocytic mitotic indexes were also significantly raised, while flux ratios only differed significantly between endemic sprue patients and control subjects. The lymphocytic infiltration was distributed focally in the upper crypt and crypt-villus interzones. Analysis of epidemic cases (presenting within 4-28 days) revealed detectable changes in lymphocyte behavior only after 3 weeks' illness, whereas mucosal lesions and malabsorption were already established during the first week. These data indicate that lymphocyte activation, suggestive of a local cell-mediated immune reaction, does occur in tropical sprue but is secondary to damage already inflicted on enterocytes and their function.