Lymphocytes and Langerhans cells in the human oesophageal epithelium

Neutrophils, eosinophils, and intraepithelial lymphocytes in the squamous esophagus in subjects with and without gastroesophageal reflux symptoms

Whilst intraepithelial lymphocytes (IELs) are considered normal within the distal esophageal mucosa, they have an increasingly recognised role in the pathogenesis of reflux esophagitis, and IEL quantification establishes the diagnosis of lymphocytic esophagitis. Knowledge regarding the upper limit of a normal IEL count in health is lacking. We studied 117 non-healthcare seeking adult volunteers from a random community sample (the Kalixanda study) with esophageal biopsies 2 cm above the gastroesophageal junction. Subjects were divided into four groups based on the presence or absence of gastro-esophageal reflux symptoms and/or esophagitis on endoscopy. Asymptomatic subjects with no endoscopic esophagitis were selected as controls, and the cell counts in this group were used to define the upper limit of normal of IELs, eosinophils and neutrophils. The entire sample was used to identify independent predictors of increased cellular counts by logistic regression analysis. None of the healthy controls had an IEL count of more than three per five high power fields (HPF), and therefore this was considered as the upper limit of normal; no controls had eosinophils or neutrophils in esophageal biopsies. Independent predictors of an elevated IEL count were spongiosis on histology (OR 11.17, 95% CI 3.32-37.58, P < 0.01) and current smoking (OR 4.84, 95% CI 1.13-2.71, P = 0.03). A receiver operating characteristics analysis concluded that a threshold of 3 IELs/5HPFs performs best in predicting reflux symptoms when a normal esophageal mucosa is visualized on endoscopy (sensitivity = 100.0%, specificity = 35.2%). The healthy esophageal mucosa does not contain more than three IELs per five HPF in the distal esophagus.

CD8 T-Cell-Predominant Lymphocytic Esophagitis is One of the Major Patterns of Lymphocytic Inflammation in Gastroesophageal Reflux Disease

CONTEXT.—

Published reports have suggested an association of lymphocytic esophagitis (LyE) with gastroesophageal reflux disease (GERD) and primary motility disorders and have also shown that GERD and motility disorders frequently overlap. These findings make it difficult to determine the true relationship between LyE and GERD, which may be confounded by the presence of motility disorders with LyE.

OBJECTIVE.—

To characterize patterns of lymphocytic inflammation in patients with GERD that have no motility abnormalities.

DESIGN.—

We identified 161 patients seen at our institution from 1998 to 2014, who were diagnosed with GERD, had normal esophageal motility, and available esophageal biopsies. LyE was defined as peripapillary lymphocytosis with rare or absent granulocytes. CD4 and CD8 immunophenotype of lymphocytes was evaluated using immunohistochemistry.

RESULTS.—

We found increased intraepithelial lymphocytes in 13.7% of patients with GERD. Two major patterns and 1 minor pattern of lymphocytic inflammation were observed as follows: (1) LyE (in 6.8% [11 of 161] of patients and typically focal), (2) dispersed lymphocytes in an area of reflux esophagitis (in 5.6% [9 of 161] and typically diffuse), and (3) peripapillary lymphocytes in an area of reflux esophagitis (in 1.2% [2 of 161]). CD8 T cells significantly outnumbered CD4 T cells in 91% of patients with lymphocytic esophagitis and 100% of patients with dispersed lymphocytes (9 of 9) or peripapillary lymphocytes (2 of 2) in the area of reflux esophagitis.

CONCLUSIONS.—

These findings suggest that LyE is one of the major patterns of lymphocytic inflammation in GERD. CD8 T-cell-predominant immunophenotype may be useful as a marker of GERD in the differential diagnosis of LyE.

Mucosal inflammation in Candida esophagitis has distinctive features that may be helpful diagnostically

The diagnosis of Candida esophagitis can be challenging when the epithelium containing Candida filamentous forms is not readily seen or is entirely sloughed away. Mucosal inflammation could be helpful diagnostically, if distinctive. However it is thought to be nonspecific in Candida esophagitis. The goal of this retrospective study was to identify features of mucosal inflammation helpful in alerting a pathologist to the possibility of Candida esophagitis when Candida mycelia are not readily observed. The study group consisted of 99 consecutive cases of Candida esophagitis and a control group of 64 consecutive cases of reflux esophagitis diagnosed at our institution from 2008-2016. Band-like superficial intraepithelial neutrophils and increased intraepithelial lymphocytes were observed in 75 and 67% of Candida esophagitis cases, respectively and only in 14 and 19% of reflux esophagitis cases, respectively (p < .0001). Intraepithelial lymphocytes were peripapillary or CD4-predominant in 75% of Candida esophagitis cases with increased lymphocytes, in contrast to 17% of reflux esophagitis cases (p = .0011). Concurrent presence of intraepithelial neutrophils and increased lymphocytes showed increased specificity for Candida esophagitis and was observed in 61% of patients with Candida esophagitis and only in 2% of patients with reflux esophagitis (p < .0001). In addition, superficial band-like neutrophils were observed concurrently with increased peripapillary lymphocytes or CD4-predominant lymphocytes in 35 and 50% of Candida esophagitis cases, respectively, in contrast to no reflux esophagitis cases. Basal cell hyperplasia and elongation of stromal papillae were frequent in both groups. The data suggest that when Candida microorganisms are not readily observed, concurrent presence of superficial band-like neutrophils and increased lymphocytes may be indicative of Candida etiology of active esophagitis.

Lymphocytic Esophagitis in Nonachalasia Primary Esophageal Motility Disorders: Improved Criteria, Prevalence, Strength of Association, and Natural History

Lymphocytic esophagitis (LE) is a histologic pattern with no established clinical correlates in the majority of patients. The goal of this study was to evaluate the association between nonachalasia primary esophageal motility disorders (PEMD) and LE. Sixty-nine patients with PEMD and esophageal biopsies, including 22 with nutcracker esophagus, 33 with ineffective motility, and 14 with diffuse spasm, constituted the study group. The control group consisted of 70 patients with severe dysmotility-negative gastroesophageal reflux disease requiring referral for Nissen fundoplication. To improve the criteria for LE, a lymphocyte reference range at different esophageal levels was first established in 17 healthy volunteers. The cutoffs for normal intraepithelial lymphocytes, defined as lymphocyte levels not exceeding mean level±2 SDs, were set at 62, 46, and 41 lymphocytes per high-power field at 0 to 2, 5, and 10 cm above the gastroesophageal junction, respectively. Predominantly focal peripapillary LE was observed in approximately 40% of patients with nutcracker esophagus or diffuse spasm and in 20% of patients with ineffective motility, in comparison with 4% of patients with dysmotility-negative gastroesophageal reflux disease (P<0.035 vs. any subtype of PEMD). Overall, LE was strongly associated with PEMD in multivariate analysis (adjusted odds ratio, 7.93; 95% confidence interval, 2.26-27.9; P=0.001). LE had a chronic course in 56% of the patients with follow-up biopsies. In conclusion, LE has a strong association with PEMD, suggesting the utility of LE in raising the possibility of PEMD.

Lymphocytic esophagitis: a histologic pattern with emerging clinical ramifications

The clinical significance of lymphocytic esophagitis (LyE), which is characterized by the prominence of peripapillary intraepithelial lymphocytes (IELs) without significant granulocytosis, remains poorly understood. During the last few years, plausible clinical correlates and novel approaches for stratification of LyE have started to emerge. Association with Crohn's disease has been established in children, but is not observed in adults. In adults, the form of LyE showing CD4⁺ -predominant IELs has been recently found to be associated with non-achalasia primary motility abnormalities. GERD is another possible association. The most common clinical manifestations of adult LyE are dysphagia and normal endoscopic appearance of the esophagus. LyE should be reported by pathologists in order to distinguish it from its mimics, such as eosinophilic esophagitis, and to assist in directing the next steps in evaluation for known associated diseases, such as Crohn's disease or motility disorders.

Lymphocytic Esophagitis With CD4 T-cell-predominant Intraepithelial Lymphocytes and Primary Esophageal Motility Abnormalities: A Potential Novel Clinicopathologic Entity

Lymphocytic esophagitis (LE) is an uncommon poorly defined histologic pattern. Its significance is largely unknown. The goal of our study was to characterize LE clinically, histologically, and immunophenotypically. Biopsies of 45 patients with LE and no intraepithelial granulocytes were selected throughout a 36-month period during routine diagnostic work. After reevaluation, complete absence of intraepithelial granulocytes was confirmed in 21 patients (LE-NG group), and few granulocytes were found in 24 patients (LE-FG). The control group consisted of 28 patients with active esophagitis consistent with reflux and overtly increased intraepithelial lymphocytes (REIL). The ratio of CD4:CD8 intraepithelial lymphocytes (IEL)>1 indicated predominance of CD4 IEL; the ratio ≤1 indicated predominance of CD8 IEL. Dysphagia was the primary complaint in 71%, 54%, and 39% of the patients with LE-NG, LE-FG, and REIL, respectively (P=0.04, LE-NG vs. REIL). Importantly, primary esophageal motility abnormalities were found in 10/11 (91%) tested LE-NG patients, 6/10 (60%) LE-FG patients, and 6/11 (54%) REIL patients. CD4 IELs were predominant in 81%, 50%, and 39% of LE-NG, LE-FG, and REIL cases, respectively (P=0.004, LE-NG vs. REIL), and in 90%, 83%, and 88% of the cases with primary motility abnormalities from the same groups. The prevalence of primary motility abnormalities was significantly higher in patients with CD4-predominant esophagitis than in patients with CD8-predominant esophagitis from all groups (21/24 [83%] vs. 2/8 [25%], P=0.005). A distinctive type of LE with predominance of CD4 IEL is associated with primary motility abnormalities suggesting a diagnostic utility of evaluating CD4 and CD8 subpopulations of T cells in LE.

Human breast milk and antiretrovirals dramatically reduce oral HIV-1 transmission in BLT humanized mice

Currently, over 15% of new HIV infections occur in children. Breastfeeding is a major contributor to HIV infections in infants. This represents a major paradox in the field because in vitro, breast milk has been shown to have a strong inhibitory effect on HIV infectivity. However, this inhibitory effect has never been demonstrated in vivo. Here, we address this important paradox using the first humanized mouse model of oral HIV transmission. We established that reconstitution of the oral cavity and upper gastrointestinal (GI) tract of humanized bone marrow/liver/thymus (BLT) mice with human leukocytes, including the human cell types important for mucosal HIV transmission (i.e. dendritic cells, macrophages and CD4⁺ T cells), renders them susceptible to oral transmission of cell-free and cell-associated HIV. Oral transmission of HIV resulted in systemic infection of lymphoid and non-lymphoid tissues that is characterized by the presence of HIV RNA in plasma and a gradual decline of CD4⁺ T cells in peripheral blood. Consistent with infection of the oral cavity, we observed virus shedding into saliva. We then evaluated the role of human breast milk on oral HIV transmission. Our in vivo results demonstrate that breast milk has a strong inhibitory effect on oral transmission of both cell-free and cell-associated HIV. Finally, we evaluated the effect of antiretrovirals on oral transmission of HIV. Our results show that systemic antiretrovirals administered prior to exposure can efficiently prevent oral HIV transmission in BLT mice.

Infected children acquire HIV from their mother in utero, intrapartum or by ingesting their mother's breast milk which can contain both HIV particles (cell-free) and HIV-infected cells (cell-associated). Although breastfeeding is attributed to a significant number of HIV infections in children, most breastfed infants remain uninfected despite prolonged and repeated exposure to HIV. This limited transmission has led to two apparently contradictory roles for milk in HIV infection: vector of transmission or vehicle of protection? Milk has a strong inhibitory effect on HIV infection in vitro. However, this has never been demonstrated in an in vivo system. In the present study, we address this paradox in a bone marrow/liver/thymus (or BLT) humanized mouse model of oral transmission of cell-free and cell-associated HIV. We demonstrate that human breast milk has potent HIV inhibitory activity that can prevent oral transmission of cell-free and cell-associated HIV in vivo. Our results provide key insight into oral HIV transmission and the protective role of milk. However, since transmission can and does occur in some instances after continued exposure to HIV in milk, we demonstrate that oral HIV transmission can be efficiently prevented in BLT humanized mice by the systemic administration of antiretrovirals.

Microscopic esophagitis and Barrett's esophagus: the histology report

Gastro-esophageal reflux disease (GERD) is the most common digestive disease in industrialized countries (Europe and North America) and is associated with microscopic changes in the squamous epithelium. However, biopsy is not presently included in the routine diagnostic flow chart of GERD. In contrast, esophageal biopsy is mandatory when diagnosing Barrett's esophagus. High quality histology reports are necessary to provide information on diagnosis and can also be important for research and epidemiological studies. It has been evident for decades that pathology reports vary between institutions and even within a single institution. Standardization of reporting is the best way to ensure that information necessary for patient management is included in pathology reports. This paper details the histological criteria for diagnosing GERD-associated microscopic esophagitis, other forms of esophagitis with specific features and columnar metaplasia in the lower esophagus (Barrett's esophagus). It provides a detailed description of appropriate sampling criteria, individual lesions and how they contribute to the histology report.

Do eosinophil numbers differentiate eosinophilic esophagitis from gastroesophageal reflux disease?

CONTEXT

Although the healthy esophageal mucosa contains no eosinophils, eosinophilic infiltration is observed in 2 major clinicopathologic settings: gastroesophageal reflux disease (GERD) and eosinophilic esophagitis (EE). The prevalence of EE is increasing in many countries, and this increase seems only partly to be due to a better awareness of the pathology, following the relatively recent description of EE. Gastroesophageal reflux disease and EE represent 2 entities that do not respond to the same treatment modalities and, thus, need to be distinguished. However, diagnostic criteria of EE have been defined arbitrarily, and the more recent articles tend to prove that the overlap with GERD is probably greater than initially believed, leading the authors to advise strict exclusion of GERD before considering the diagnosis of EE.

OBJECTIVES

To provide pathologists with the currently proposed histologic criteria of GERD and EE, to stress the need to combine these criteria with clinical data and endoscopic findings, and to outline the remaining controversies.

DATA SOURCES

This review is based on selected articles identified by a PubMed (US National Library of Medicine, Bethesda, Maryland) search of the literature in English for GERD and EE, a recent review by the American Gastroenterological Association (Bethesda), the Proceedings of the First International Gastrointestinal Eosinophil Research Symposium, and the authors' experience.

CONCLUSION

Proper identification of the etiology of eosinophilic infiltration of the esophagus allows accurate medical or surgical treatment and follow-up. Eosinophilic esophagitis and GERD diagnoses require integration of the histologic findings with the clinical and endoscopic data.

A note on langerhans cells in the oesophagus epithelium of domesticated mammals

Using the zinc-iodide osmium tetroxide (ZIO) method, TEM and immunohistochemistry (for CD1a and langerin), the study demonstrates Langerhans cells in the oesophageal epithelium of domesticated mammals (herbivores: horse, cattle, goat; omnivores: pig, dog, laboratory rat; carnivores: cat), although with variations between the species. The ZIO method and TEM showed this cell type in the cat and, sporadically, in the horse; CD1a (+) Langerhans cells were demonstrated in the ovine, porcine and murine oesophagus. Positive staining for langerin was detected in single cells of the caprine, canine, murine and feline oesophagus and more distinct in almost all the cell layers of the equine and porcine oesophagus epithelium. The findings are discussed comparing specifically the results for CD1a and langerin, whereby the latter C-type lectin may be of importance in species with a rather thick oesophagus epithelium, such as that present in the plantivorous and most of the omnivorous animals, where antigenic pressure is reduced.

The role of lymphocytes in eosinophilic gastrointestinal disorders

Eosinophilic gastrointestinal diseases (EGIDs) encompass a variety of disorders including eosinophilic esophagitis (EE), eosinophilic gastroenteritis (EG), and eosinophilic colitis. Although the pathogenesis of EGIDs is still poorly understood, dietary food antigens have been shown to cause EGIDs through several short-term clinical studies. The relationship of EGIDs with food allergy points to a potential breach of oral tolerance in EGIDs and to a potentially important role played by lymphocytes in responding to the oral food antigens. This article discusses the concept of oral tolerance, the available evidence for the role that lymphocytes play in the induction and pathogenesis of EGIDs, and the evidence for a potential breach in oral tolerance in EGIDs.

Lymphocytic disorders of the gastrointestinal tract: a review for the practicing pathologist

Increased numbers of intraepithelial lymphocytes (lymphocytosis) can be found in the esophagus, stomach, small intestine, and colon in a variety of clinical circumstances. This review, directed at practicing pathologists, portrays the normal resident lymphocyte population in the mucosa of each segment of the digestive tract and discusses the different situations that may result in quantitative or qualitative alterations of intraepithelial lymphocytes. Esophageal lymphocytosis has not been fully characterized and its clinical significance, if any, awaits definition. Thus, this diagnosis is presently discouraged. In the stomach, it is particularly important to exclude Helicobacter pylori infection and celiac sprue before diagnosing lymphocytic gastritis. Duodenal lymphocytic infiltrates, inextricably tied with alterations of the villous architecture of the mucosa, are often caused by gluten sensitivity. However, similar morphologic changes may be caused by a vast array of other conditions that must be carefully considered and excluded. Lymphocytic and collagenous colitis are most often unexplained, but their frequent association with autoimmune conditions or certain medications deserve a thorough investigation in each case. Using a combination of histologic and clinical clues, a cause for the intraepithelial lymphocytic infiltration can be identified in many instances. As some of the associated conditions are amenable to effective treatment, the importance of diligently seeking such associations before resorting to a diagnosis of primary lymphocytosis is emphasized.

Immunopathological mechanisms of eosinophilic oesophagitis

BACKGROUND

Eosinophilic oesophagitis (EO) is a chronic inflammatory disease of the oesophagus, with an emergent character, defined by the presence of a dense infiltrate by eosinophilic leukocytes restricted to the mucosa of this organ after excluding gastro-oesophageal acid reflux. It is manifested by chronic and/or recurrent dysphagia and episodes of oesophageal alimentary impaction, with great variation in terms of intensity, frequency, and duration of the attacks.

METHODS

An Internet-based search was performed for the most recent articles with relevant information concerning immunopathological mechanisms involved in EO.

RESULTS

Bibliographical data allow us to define that EO is related to an allergic or hypersensitivity-induced reaction after exposure to foods or inhalants, with increased prevalence of sensitisation to these allergens. Data published up to now suggest a cellular hypersensitivity reaction rather than a humoral one in the physiopathology of EO. In this disease, sensitised T-lymphocytes mediate a Th2 type response, releasing cytokines such as IL-5, with a possible Th1 component that requires further investigation. The function of the abundant CD8+ T-lymphocytes present in the oesophageal epithelium has yet to be explained. Mast cells also participate in epithelial inflammatory infiltrate in EO, and it is still unknown if its activation, mainly through IgE, contributes to the immunopathology of the disease even though EO rarely manifests immediate hypersensitivity reactions. IL-5 and different forms of eotaxins perform an important active role in the recruitment of eosinophils to the oesophagus.

CONCLUSIONS

EO is an immunologically complex and little studied entity that is associated with other allergic diseases and in which different effector cells participate, determining an immunological response of cellular rather than a humoral hypersensitivity reaction. The data available point out that EO is a disorder of the Th2 retarded immune response, in which the triggering factor might not be IgE. Although the final inflammatory phenomena observed in EO are common for the different patients, the cascade of inflammatory mediators that lead to them might not be identical in all cases, and the morphological and functional disorders observed in EO would represent the final convergence of different activation forms of the mechanisms of inflammation.

Immunologic function of dendritic cells in esophageal cancer

Esophageal cancer is one of the frequently occurring malignant cancers. The current therapy, including surgery, chemotherapy, radiotherapy, or a combination, is only to palliate the symptoms; overall the prognosis is poor. The immunotherapy of dendritic cells for esophageal cancer is a valuable method. Dendritic cells existing in the esophageal tissues play an important role in the host's immunosurveillance against cancer as the professional antigen-presenting cells. This review concerns the immunology of dendritic cells in esophageal cancer; it describes the expression of DCs in the normal esophageal tissues and benign disease of esophagus, relations between the DCs and cancer development in esophageal cancer, and the DC-based approach to establish treatment for esophageal cancer.

Proton pump inhibitor therapy in gastro-oesophageal reflux disease decreases the oesophageal immune response but does not reduce the formation of DNA adducts

BACKGROUND

Chronic oesophageal inflammation and related oxidative stress are important in the pathogenesis of erosive oesophagitis (EO) and its malignant progression.

AIM

To study the effect of proton pump inhibitors (PPIs) on oesophageal cellular immune response and oxidative damage in EO patients.

METHODS

Forty gastro-oesophageal reflux disease (GERD) patients [non-erosive reflux disease (NERD): 15, EO: 25] were included, after 7 days off antisuppressive drugs. EO patients were randomized to 20-mg rabeprazole once daily for either 4 or 8 weeks with baseline and follow-up endoscopy with distal oesophageal biopsies. T lymphocytes, macrophages and mast cells were quantified by immunohistochemistry. DNA adducts were measured by analysis of 8-oxo-deoxyguanosine levels.

RESULTS

Erosive oesophagitis patients had more T lymphocytes and CD8(+) T lymphocytes in squamous epithelium than NERD patients (P = 0.001, P = 0.002, respectively). Levels of DNA adducts between both groups were, however, not different (P = 0.99). Four- and eight-week rabeprazole treatment in EO patients resulted in a significant decrease in number of T lymphocytes and CD8(+) T lymphocytes (all P < 0.05). PPIs did not, however, affect levels of DNA adducts.

CONCLUSIONS

Short-term PPI therapy in EO patients reduces the oesophageal cellular immune response, but does not change oxidative damage. PPI therapy may therefore not be effective in reducing the risk of oesophageal cancer in GERD patients.

Translational research on the pathogenesis of eosinophilic esophagitis

Eosinophilic esophagitis (EE) is an inflammatory disease of the esophagus characterized by eosinophilic infiltration of the esophageal epithelium. EE is a relatively new disease from clinical and research standpoints. A recent surge in basic and translational studies has emerged to understand its pathogenesis since its recognition as a separate entity from acid-induced gastroesophageal reflux disease in 1995. Our understanding of this disease is still limited, however. In this article, available evidence from translational studies on EE is discussed, focusing on the allergic nature of the disease and highlighting the role of various inflammatory cells found in the esophagus of patients who have EE. Esophageal remodeling in EE is also discussed.

Immunophenotypic characterization and quantification of the epithelial inflammatory infiltrate in eosinophilic esophagitis through stereology: an analysis of the cellular mechanisms of the disease and the immunologic capacity of the esophagus

Eosinophilic esophagitis (EE) is an emerging disease caused by dense infiltration of the esophageal epithelium by eosinophilic leucocytes. It is originated from local hypersensitivity to food or airborne allergens. Although the physiopathologic mechanisms of the illness have not been fully discovered, EE is a loss of immunologic tolerance by the esophagus, meaning that it should be considered as an active immunologic organ. In our study, we investigated the immunologic capacity of the epithelium using immunohistochemistry and stereology, to determine the cellular density of eosinophils, T and B lymphocytes, Langerhans cells, mast cells, and cells manufacturing immunoglobulin E in endoscopic biopsies of patients with EE (taken before and after topical treatment with fluticasone propionate) compared with normal individuals and patients suffering from gastroesophageal reflux disease (GERD). We have observed that the density of eosinophils in EE is 300 times greater than in normal conditions and it is only in this disease where eosinophils show signs of activation and degranulation (positivity to major basic protein immunostaining). The number of T intraepithelial lymphocytes also significantly rose in EE, compared with other entities, where CD8 cells were predominant. However, the human esophagus is deficient in B lymphocytes and we only found intraepithelial plasma cells that excreted immunoglobulin E in EE. Under normal conditions mast cells exist in the thickness of the epithelium that are slightly higher in GERD and multiply in density by 17 in EE. Langerhans cells did not show any significant variation in density under the different tested conditions. After topical treatment with steroids, the density of the different cell components fell to similar levels to GERD. Using our study, we can conclude that the human esophagus may contribute to the development of local immunologic responses as it contains all the necessary cell components. EE represents growth of this esophageal capacity and its pathogeny could respond to mixed cellular and humoral mechanisms.

Esofagitis eosinofílica

Eosinophilic esophagitis is characterised for a dense infiltration of the esophagus by eosinophilic leukocytes. The disease's origin is a local reaction to different antigens of which the patient presents previous sensitization, acquired by digestive, inhaled or even epicutaneous exposure. The esophagus contains different cellular types resident in its structure, with capability to participate in the capture, processing and antigens' presentation to T lymphocytes, which could initiate a T helper 2-type immunological response mostly mediated by interleukin-5, with a possible T helper 1-type component. Local production of immunoglobulin E could also participate in the pathophysiology of eosinophilic esophagitis, and for this reason, this disease can be considered a mixed-humoural and cell-mediated immunological disturbance. Studies directed to identificate responsible allergens must consider test for determine immunoglobulin E-mediated reactions as well as cell-mediated hyper-responsiveness responses. Main symptom of eosinophilic esophagitis are dysphagia and esophageal food impactations, which are conditioned by endoscopic alterations and motor disturbances objectively demonstrated by manometric recorders. Eosinophil and mast cell's activation and degranulation against responsible antigens cause damage over esophageal epithelium and dynamic disturbances over neuromuscular components in esophageal wall. Therapies proposed for eosinophilic esophagitis include control of antigen exposition, endoscopic dilation of stenosis and drugs with antieosinophilic effect; in this group topical steroids can be outlined for the capacity of them to restore the histology and the esophageal motility in parallel to vanishment of inflammation.

Review article: the nature of oesophageal injury in gastro-oesophageal reflux disease

The purpose of this review was to explore issues relating to the nature of oesophageal injury in gastro-oesophageal reflux disease. Several structural and functional elements of the oesophageal epithelium provide for an inherent resistance against refluxed material. It is only when this defence is overcome that reflux-induced damage ensues. The light microscopic changes in reflux oesophagitis are manifold. Early changes are confined to the epithelium and consist of reactive changes and inflammatory cell infiltration. When the epithelial integrity can no longer be maintained, erosions and ulcers develop. Recently, dilatation of the intercellular spaces was described as a sensitive early marker for gastro-oesophageal reflux disease. This parameter was first identified by electron microscopy but can also be assessed by light microscopy in routinely stained tissue sections. Some of the changes occurring in early gastro-oesophageal reflux disease can be reproduced by incubating oesophageal mucosal biopsies in gastrointestinal fluids or their components. Activated pepsin, trypsin and conjugated bile acids at an acidic pH have been identified as probable causes of reflux-induced damage.

Is There a Set of Histologic Changes That Are Invariably Reflux Associated?

Many histologic changes have been described in the esophageal squamous mucosa in patients with gastroesophageal reflux disease (GERD), including dilated intercellular spaces, balloon cells, intrapapillary vessel dilation, elongated papillae, basal cell hyperplasia, acanthosis, intraepithelial eosinophils, Langerhans cells, and p53 protein overexpression. To define a set of histologic changes that are invariably reflux associated, we examined the histologic changes in esophageal specimens from normal controls, patients with GERD, patients without GERD but with a suspicion of other pathology, and patients with esophageal carcinoma. We also examined biopsy specimens from sites with differing endoscopic features, including cloudy white and reddened mucosa. A definitive set of reflux-associated histologic changes could not be defined from the small number of biopsy specimens examined in the present study. Histologic changes indicative of GERD are likely to be found somewhere in the esophagus in all patients with GERD, but these changes are nonspecific. A set of histologic changes that are invariably reflux associated may exist, but these changes are nonspecific. To develop a set of characteristic reflux-associated features, endoscopists may perform targeted biopsies from several sites with various endoscopic features and at different stages of disease.

Variation in Langerhans cell number and morphology between the upper and lower regions of the human esophageal epithelium

Langerhans cells (LCs) are dendritic components of stratified epithelia, presenting antigens to other cells of the immune system that play a crucial role in local defense. The paucity of information about their significance in the esophageal mucosa was addressed by studying their distribution and morphology in this particular location. LCs were identified by immunohistochemical detection of CD1a, a cell-specific marker, using a monoclonal antibody, as well as by electron microscopic identification of characteristic Birbeck granules, among other typical morphological features. Cell counts carried out at 25 and 35 cm distal to the dental arch demonstrated significant differences in number and size between the two locations. The upper region contained 10.4 +/- 0.8 cells (mean +/- SEM) vs. 18.4 +/- 1.4 cells in the lower region. Also, cells in the lower region were larger and appeared to have longer dendritic processes. To our knowledge this is the first report of regional differences in number and morphology of LCs in human esophageal mucosa.

The organization of the communication routes between the epithelium and lamina propria mucosae in the human esophagus

Morphological studies examined communication routes between the epithelium and lamina propria mucosae in the human esophagus, using a series of techniques including silver staining, immunohistochemistry, transmission electron microscopy, and scanning electron microscopy (SEM). For SEM, tissue blocks were treated with either osmium/ultrasonication or NaOH. Observations showed the esophageal papillae to be arranged regularly in a mostly longitudinal row. The reticular fibers, consisting of fibrils approximately 40 nm in diameter, were situated just beneath the epithelial basal lamina. They showed a positive reaction with a type III collagen antibody, and formed a continuous sheet 2-3 microm thick with dense networks. This sheet as well as the epithelial basal lamina had numerous foramina of diameters of 3-5 microm. Immune cells such as lymphocytes and Langerhans cells were situated around these foramina. The foramina were situated both around papillae and the duct orifice of the esophageal gland. In addition, lymphoid follicles surrounded the duct of the esophageal gland. The structural characteristics around the duct appear to be those of duct-associated lymphoid tissue (DALT). Thus, these foramina in the epithelial basal lamina and reticular fiber sheet may represent important communication routes between the epithelium and lamina propria mucosae. In addition, they may play an important role in the mucosal immune response in the human esophagus.

Langerhans cell-like dendritic cells in the cornea, tongue and oesophagus of the chicken (Gallus gallus)

Langerhans cells are dendritic leucocytes which reside mainly within stratified squamous epithelia of skin and mucosa. Their visualization requires the use of ATPase histochemistry, electron microscopy for identifying the unique trilaminar cytoplasmic organelles (the Langerhans cell granules or Birbeck granules), and the expression of major histocompatibility complex class II molecules. Following uptake of antigen, Langerhans cells migrate via the afferent lymphatics to the lymph nodes and undergo differentiation from an antigen-processing cell to an antigen-presenting cell. Using the same approach as that employed in previous studies for the identification of chicken epidermal Langerhans cells, we show here the presence of ATPase-positive and major histocompatibility complex class II-positive Langerhans cell-like dendritic cells at the mucosal surface of the eye, tongue and oesophagus of the chicken. Ultrastructurally, these cells qualified as Langerhans cells except that they lack Langerhans cell granules. Thus, as in mammalian skin and mucosa, chicken mucosa contains mucosal dendritic cells with morphological and phenotypical features for the engagement of incoming antigens within epithelium and lamina propria.

Squamous mucosal alterations in esophagectomy specimens from patients with end-stage achalasia

Achalasia is an esophageal motor disorder in which the primary morphologic changes are found in the myenteric plexus. However, a number of secondary alterations are characteristically found in esophagectomy specimens, including the mucosa. In addition, these patients are at increased risk of developing esophageal squamous cell carcinoma. We studied the squamous mucosal alterations in 35 esophagectomy specimens from patients with end-stage achalasia and compared them with those found in the squamous mucosa near the esophagogastric junction from pediatric autopsies (</=18 years) from patients with no known esophageal disease. A representative block was immunostained for p53 (DO7), CD3, and CD20. p53 immunoreactivity was graded as follows: 0 = no staining; 1+ = rare basal cell staining; 2+ = extensive basal cell staining; 3+ = suprabasilar staining. Intraepithelial lymphocyte counts were performed by counting five high power fields (HPF) and calculating an average/HPF. Ages of achalasia patients at esophagectomy ranged from 21 to 78 years (mean 56 years), including 20 men and 15 women. Disease duration ranged from 1 to 44 years (mean 17 years). In all cases the squamous mucosa from achalasia patients was markedly hyperplastic with papillomatosis and basal cell hyperplasia. p53 staining in the squamous mucosa from achalasia patients was significantly more common than in controls (32 of 35 [91%] vs 1 of 17 [6%]; p <0.05). In all achalasia cases CD3+ cells far outnumbered CD20+ cells. There was a significantly greater number of CD3+ cells in achalasia cases (range 32-239/HPF; mean 107/HPF) compared with controls (range 0.8-12/HPF; mean 6/HPF) (p <0.05). In conclusion, the squamous mucosa in esophagectomy specimens from patients with end-stage achalasia shows significant alterations including marked squamous hyperplasia, an increased frequency of p53 immunoreactivity, and increased numbers of CD3+ cells when compared with controls. These changes may be related to the increased risk of squamous cell carcinoma in these patients.

Aberrant esophageal HLA-DR expression in a high percentage of patients with Crohn's disease

Esophageal histology is not well studied in patients with Crohn's disease (CD). We, therefore, analyzed the histologic and immunohistologic appearance of esophageal mucosa in CD. Biopsy specimens taken from the esophagus of 57 consecutive patients with known CD of the large and/or small bowel, of 200 Crohn's-free controls, of 15 cases with ulcerative colitis, and of 5 cases with viral esophagitis were evaluated. In controls, most patients had either HLA-DR negative esophageal epithelium or showed focal or diffuse basal staining. HLA-DR expression of all epithelial layers (transepithelial staining) was observed in only four (2%) control subjects, in one case with herpes esophagitis, but not in patients with ulcerative colitis. In contrast, transepithelial HLA-DR expression was found in 19 (33%) patients with CD (p < 0.0001). In CD patients, it was associated with a significantly increased epithelial content in T-cells (CD3+, TIA-1+, granzyme B+), B-cells (CD79a+), natural killer cells (CD57+), and macrophages (CD68+). There was no correlation with either histological findings elsewhere in the upper gastrointestinal tract or with laboratory findings, symptoms, CDAI, or medication. Transepithelial esophageal HLA-DR expression is common in CD. Immunohistochemistry may prove useful in supporting the histologic diagnosis of CD in staging procedures, for initial diagnosis as well as in doubtful cases.

Reduced number of Langerhans cells in oesophageal mucosa from AIDS patients

AIMS

The oesophageal mucosa is a frequent target of opportunistic infections in human immunodeficiency virus (HIV) infection. Langerhans cells (LC) are known as a target and reservoir of HIV in the skin. The aim of this study was to characterize oesophageal LC in HIV-infected patients.

METHODS AND RESULTS

Thirty oesophageal biopsies were obtained from 29 patients (median age 35.5), all in stage IV of the HIV Center of Disease Control Classification. We performed histological assessment of the oesophageal mucosa and immunohistochemical detection of oesophageal LC using an anti-CD1a antibody, followed by morphometric analysis. Biopsies from 17 noninfected patients were studied using the same procedure. LC in oesophageal mucosa of the HIV positive patients showed a significantly and dramatically decreased number (LC(N) median = 5.85/mm2) and surface/epithelial surface (LC (S) ratio = 0.09) when compared with HIV-negative controls (LC(N) median = 29.7/mm2, LC(S) ratio = 1.83) with P = 0.003 for LC(N) and P < 0.0001 for LC(S).

CONCLUSION

These data suggest that oesophageal LC are, like their epidermal counterparts, a preferential target for HIV infection. Their alterations may provide a clue to the pathogenesis of the decreased local oesophageal immunity and to the occurrence of opportunistic infections.

Esophageal morphology from Linxian, China. Squamous histologic findings in 754 patients

BACKGROUND

Linxian, China, has one of the highest rates of esophageal cancer in the world. Other authors have described high prevalences of histologic esophagitis, atrophy, and dysplasia in Linxian and have suggested that these findings may represent precancerous lesions in this population. In 1987, a new endoscopic survey allowed the authors to make an independent study of esophageal histology in Linxian.

METHODS

There were 1567 satisfactory squamous esophageal biopsies available from 754 patients. These biopsies were classified as normal, atrophy, acanthosis, esophagitis, squamous dysplasia, or squamous cancer.

RESULTS

Classified by their worst diagnosis, 56.5% of the 754 patients had normal mucosa, 0.0% atrophy, 11.5% acanthosis, 4.6% esophagitis, 22.7% squamous dysplasia, and 4.6% squamous cancer.

CONCLUSIONS

The results show a different distribution of esophageal squamous diagnoses than has been reported previously from this population. The authors believe that the major reason for this discrepancy was differences in histologic criteria. In this survey, seemingly small differences in criteria could cause large differences in apparent disease prevalence; this was especially true for esophagitis. By the criteria used in this study, histologic esophagitis and atrophy are uncommon findings in Linxian, raising questions about their significance as precursor lesions of esophageal cancer in this population.

Langerhans cells and lymphocyte subsets in human gastrointestinal carcinomas. An immunohistological study on frozen sections

In an immunohistochemical study of 38 human gastric and 40 human colonic carcinomas Langerhans cells, suppressor and helper lymphocytes were identified on frozen sections by using anti-CD1, anti-CD8 and anti-CD4 monoclonal antibodies. Tumours were divided into those with few (< 3 per high power field) and those with many (> 3 per high power field) Langerhans cells as well as into those with high number of CD4 and CD8 cells (> 30 per high power field). No significant difference in the number of Langerhans cells regarding histologic types, degree of differentiation and metastatic/non-metastatic groups of either gastric or colonic carcinomas was found. On the contrary the numbers of Langerhans cells related significantly (p < 0.05) to density of T-cell and especially CD4 cell infiltrations of gastric and colonic carcinomas. This finding supports the role of Langerhans cells as antigen presenting cells and their involvement in T-cell activation against neoplastic cells of human gastrointestinal carcinomas.

Localization of calcitonin gene-related peptide in human esophageal Langerhans cells

Previously undescribed calcitonin gene-related peptide-immunoreactive intraepithelial cells were seen in specimens of esophageal mucosa obtained by biopsy or surgical resection from 14 individuals. These calcitonin gene-related peptide-immunoreactive cells were sparsely seen in normal mucosa but increased markedly in esophagitis. They were inaccessible to routine histological stains, but osmication showed them as dendritic forms resembling Langerhans cells of the skin. Their cytological identity was determined with immunocytochemical tests for human antigenic markers such as Ia, HLA-DR, and OKT6 for Langerhans cells, Leu-M5 and Leu-M3 for intraepithelial macrophages, CD3 and TCR-1 for T-lymphocytes, Leu-14 for B-lymphocytes, S-100 for Merkel cells, and chromogranin for amine precursor uptake and decarboxylation cells. Double localization showed that calcitonin gene-related peptide immunoreactivity colocalized with Ia, HLA-DR, and OKT6 but not with the other markers. These studies show that intraepithelial Langerhans cells in the esophageal mucosa contain calcitonin gene-related peptide, which may serve as an immunomodulator.

Langerhans cells of human mucosa

The ontogeny of human LC and their presence in all Malpighian epithelia underline their important role in immunoregulation of the skin and mucous membranes. LC are also found in buccal and esophageal mucosa, in cornea and conjunctiva, in pulmonary, vesical, vaginal and cervical epithelia as well as in placenta villi. In all these Malpighian epithelia, the presence of DR + LC is necessary and essential for the surveillance function against allergo-antigens and the emergence of neo-antigens associated with malignant transformations.

S-100 protein-positive dendritic cells in colorectal adenocarcinomas. Distribution and relation to the clinical prognosis

Dendritic cells (DC) in 121 colorectal adenocarcinomas were investigated immunohistochemically, using anti-S-100 protein antibody. S-100(+)DC were recognized among the malignant cells and/or around the tumor and differed in distribution either from lysozyme-positive macrophages or from neuron-specific enolase-positive neural tissue. Patients with many S-100(+)DC (more than 30 cells per 10 high-power fields) in the tumor survived longer than did those with few such cells (less than 30 cells), most often with no metastases (P less than 0.001). The grade of S-100(+)DC infiltration was related to both density of lymphocytic infiltration in the primary tumor and the degree of paracortical hyperplasia in the regional lymph nodes (P less than 0.05). Dendritic cells, therefore, as antigen-presenting cells, conceivably mediate cell immunity in a tumor with lymphoid infiltration and in the regional lymph nodes. The number of S-100(+) DC in the primary colorectal carcinomas represents one aspect of such a series of antitumor immunoreaction, in vivo.

S-100 protein-positive dendritic cells in colorectal adenocarcinomas. Distribution and relation to the clinical prognosis

Dendritic cells (DC) in 121 colorectal adenocarcinomas were investigated immunohistochemically, using anti-S-100 protein antibody. S-100(+)DC were recognized among the malignant cells and/or around the tumor and differed in distribution either from lysozyme-positive macrophages or from neuron-specific enolase-positive neural tissue. Patients with many S-100(+)DC (more than 30 cells per 10 high-power fields) in the tumor survived longer than did those with few such cells (less than 30 cells), most often with no metastases (P less than 0.001). The grade of S-100(+)DC infiltration was related to both density of lymphocytic infiltration in the primary tumor and the degree of paracortical hyperplasia in the regional lymph nodes (P less than 0.05). Dendritic cells, therefore, as antigen-presenting cells, conceivably mediate cell immunity in a tumor with lymphoid infiltration and in the regional lymph nodes. The number of S-100(+) DC in the primary colorectal carcinomas represents one aspect of such a series of antitumor immunoreaction, in vivo.

Experimental chlamydial keratitis in rabbits. Correlation with chlamydia infected McCoy tissue culture cells

Rabbit corneas were inoculated three times at weekly intervals with the agent of chlamydia trachomatis using the scratch method. Specimens of the corneal epithelium were obtained using the replica technique on the 1st, 2nd, 3rd and 4th day after each inoculation and at two weeks after the last inoculation. The development of chlamydial inclusions and the inflammatory cell response were monitored using Giemsa stain, acridine orange stain and direct immunofluorescent technique. Primary inoculation produced mild clinical disease associated cytologically with polymorphonuclear leucocytic cellular inflammatory response. Repeated inoculations produced more severe disease associated clinically with pannus formation and cytologically with the presence of lymphocytes and Leber cells in addition to polymorphonuclear leucocytes. Halberstaedter Prowazek inclusion bodies were detected in all the specimens. Additional intracytoplasmic and intranuclear inclusions of different morphological appearances were present. The cytological findings detected in the corneal epithelium of rabbits were correlated with the findings in McCoy tissue culture cells inoculated with chlamydia trachomatis.

Intestinal nodular lymphoid hyperplasia in patients with common variable immunodeficiency: local accumulation of B and CD8(+) lymphocytes

Common variable immunodeficiency (CVI) with hypogammaglobulinemia is often complicated by nodular lymphoid hyperplasia of the intestine. In this study the lymphoid constituents of intestinal nodular hyperplasia of five CVI patients were characterized with monoclonal antibodies. Few CD4(+) but abundant CD8(+) T lymphocytes were found around the follicles. The follicles were populated mainly by B cells expressing surface IgM. A few cells in the lamina propria expressed Leu7. No intracytoplasmic immunoglobulin-containing plasma cells were seen. Peyer's patches in gut biopsies from controls were also composed of follicles with B lymphocytes. A ring of T lymphocytes surrounded the follicles. CD4(+) helper cells largely outnumbered CD8(+) cells in this ring. Moreover, plasma cells were present in the lamina propria and the mixed cell zone covering the follicles. In peripheral blood of the patients, B cells were present in normal proportions but they could not be induced to produce IgG in vitro by T cell-dependent (pokeweed mitogen) or T cell-independent (Staphylococcus aureus Cowan I) mitogens. In two of the patients, IgM production could be induced in vitro. Peripheral blood T cells were predominantly CD8(+) in three of the five patients, and in these same patients an increase in suppressor-cell activity of peripheral blood T cells on immunoglobulin production was observed. The data demonstrate a block in B-cell differentiation in the gut and in peripheral blood. Whether the local increase in CD8(+) cells in the nodular lymphoid hyperplasia is a primary event or is secondary to chronic immune stimulation and whether it contributes to local inhibition of B-cell differentiation remain to be investigated.

Jejunal mucosa lymphoid cell subsets and the expression of major histocompatibility complex antigens in children

Using monoclonal antibodies with the immunoperoxidase technique the distribution pattern of class I and class II antigens of the major histocompatibility complex (MHC), and of the lymphocyte subsets have been studied in intestinal biopsies from children without mucosal lesions, from children with coeliac disease (CD) and from infants with cow's milk protein intolerance (CMPI). The staining of the intestinal mucosa for class I antigens is unaltered irrespective of the histological picture or the clinical diagnosis. Class II antigens are only partially or not expressed at all by epithelial cells in untreated coeliac disease and in some cases of cow's milk protein intolerance. The number and the composition of the lamina propria lymphocytes in both CD and CMPI are different from the normal situation. An increase of all lamina propria lymphocyte subsets is observed in untreated CD. A decrease of OKT4+ lymphocytes is observed in the lamina propria of CMPI patients. These changes may be involved in the pathogenesis of these diseases.

Does radiation-induced abrogation of skin Langerhans cell functions lead to enhanced incidence of skin tumors in patients with genetic disorders of DNA repair?

A hypothesis is presented which states that persons with the genetic disorders xeroderma pigmentosum and ataxia-telangiectasia, manifested by a deficiency of DNA repair, develop cutaneous tumors due to the elimination of reticuloendothelial system cells (Langerhans cells) in the skin, and the subsequent loss of control of epidermal cellular elements.

Lymphocytic subpopulations in the normal human conjunctiva. A monoclonal antibody study

Monoclonal antibodies were used to analyze the lymphocytic subpopulations in frozen tissue sections of normal human conjunctiva (epibulbar, tarsal, and forniceal). The overwhelming majority of lymphocytes were T-cells (Leu1+ and OKT8+). In the epithelium, the predominant cell type was the OKT8+ cytotoxic/suppressor cell, whereas in the substantia propria, helper T-cells (Leu3a/3b+) equalled suppressor T-cells. T-cells outnumbered B-cells 20-fold; the letter cells were detected only in the substantial propria, particularly in the fornices, and not in the epithelium. Plasma cells, as identified by OKT10 staining, were completely absent except in the accessory lacrimal glands of Krause. Langerhans' cells, identified by OKT6 and HLA-DR (la) staining, were observed in the epithelium of all conjunctival regions. Our findings suggest that the reactivity of B-lymphocytes and plasma cells is heavily damped down by T-lymphocytes, thus allying the conjunctiva to other mucosal membranes and the skin as heavily immunoregulated tissues.

Human oesophageal submucosal glands. Their detection mucin, enzyme and secretory protein content

Human oesophageal submucosal glands may be regularly demonstrated by first exposing the oesophageal lumen to toluidine blue which reveals the duct ostia. Four types of cell were identified in the glands - mucous, subsidiary or serous, myoepithelial and oncocytes. The mucous cell contained neutral, sialated and sulphated mucins. The subsidiary cells held smaller amounts of neutral and sialated mucin, plus fucosyl residues. No lipids were detectable histochemically. ATP-ase and alkaline phosphatase were shown in the capillary endothelium. The duct epithelium showed some nonspecific esterase activity not sensitive to E 600. By immunoperoxidase techniques, the duct epithelium was shown to be rich in cytokeratin. The subsidiary cells contained lysozyme, CEA and pepsinogen. B lymphocytes composed most of the periductular lymphoid aggregates, although some T cells were found there and also intraepithelial and subepithelial in relation to the stratified squamous epithelium lining the oesophagus. Langerhans' cells were also demonstrated as intraepithelial by several techniques.

Pattern of distribution of T lymphocytes, Langerhans cells and HLA-DR bearing cells in normal human oral mucosa

The tissue distribution of helper/inducer and suppressor/cytotoxic T cells, Langerhans cells (LC) and HLA-DR bearing cells was determined in normal oral mucosa by use of monoclonal antibodies OKT4, OKT8, OKT6 and OKIa1, respectively. OKT4+ and OKT8+ cells were invariably present in normal oral epithelium and in the lamina propria. OKT8+ cells were consistently seen inside the basal cell layer of the epithelium. The distribution of LC in oral epithelium showed regional variation. In palatal epithelium LC were evenly distributed in the basal half of the epithelium, whereas in buccal mucosa the highest concentration of LC was seen in the epithelium overlying the tips of connective tissue papillae. OKIa1 stained dendritic cells in the epithelium and plump cells with small dendritic processes in the connective tissue. Some of the latter were located close to the basal cells of the epithelium. The consistent relationship between immunocompetent cells and the epithelium of the oral mucosa suggests the presence of a local immunologic defence barrier in the oral mucosa.

Langerhans' cells and lymphocyte subsets in the female genital tract

Cryostat sections of healthy cervical, vaginal and vulval epithelium were examined using immunohistological labelling techniques and a panel of monoclonal antibodies recognizing Langerhans' cells, T- and B-lymphocytes and HLA-DR antigen. The distribution of Langerhans' cells in squamous epithelium of the cervix, vagina and vulva showed a marked variation with the highest median values in the vulva (18.7 per 100 basal squamous cells) and the lowest in the vagina (5.5 per 100 basal squamous cells). There was also a substantial variation in number and distribution of lymphocytes of each of these three areas with a distinct preponderance in the transformation zone of the cervix. In addition, intraepithelial lymphocytes, predominantly of the T-cytotoxic suppressor sub-type were present at all sites with the greatest number in the transformation zone. We conclude from this study that lymphoid tissue of the cervical transformation zone has several unique characteristics which are not observed at other sites in the lower genital tract. We suggest that this tissue be designated 'cervical lymphoid tissue' and that it forms a part of the 'mucosal associated lymphoid tissue' (MALT) as noted at other mucosal sites exposed to the external environment.

Expression of MHC Class II antigens by oesophageal epithelium in herpes simplex oesophagitis

An immunoperoxidase technique with monoclonal antibodies for the identification of lymphocyte subsets and MHC Class II antigens was applied to oesophageal biopsies from two patients with herpetic oesophagitis. Oesophageal epithelial cells were found to express the MHC Class II antigen. The inflammatory infiltrate of the lamina propria was composed of both B lymphocytes and T lymphocytes.

Endometrial lymphoid tissue: an immunohistological study

Lymphoid tissue of the endometrium was analysed by histological, immunohistological, and electron microscopical methods in 10 healthy uteri. A panel of monoclonal antibodies recognising macrophages (OKMI), HLA-DR antigen, B lymphocytes, T lymphocytes and their subsets, and dendritic reticulum cells was used in a two stage indirect immunoperoxidase labelling technique. Endometrial lymphoid tissue showed a remarkably consistent pattern of labelling in all cases. Lymphoid tissue was present in three sites: namely, (i) intraepithelial lymphocytes (predominantly T lymphocytes with occasional macrophages) associated with periglandular and sub-epithelial HLA-DR+, OKMI+ macrophages; (ii) interstitial lymphocytes and macrophages; (iii) lymphoid aggregates in the stratum basalis. These were composed mainly of T lymphocytes with a few B lymphocytes. Dendritic reticulum cells were found in those occasional lymphoid aggregates in which germinal centres were present. These features suggest that endometrial lymphoid tissue has many of the hallmarks of mucosal associated lymphoid tissue as found elsewhere in the body--for example, the bronchus and intestine. Endometrial lymphoid tissue appears to be unique, however, in that most of the stratum functionalis in which it is situated shows cyclical shedding during the menstrual cycle.

Lectin-binding spectra in the hyperplastic human tonsil. Effect of formalin fixation and paraffin embedding on lectin affinity of tissue components

In order to determine the effect of routine fixation on the lectin affinity of tissue structures, we used unconjugated lectins and an indirect immunoalkaline-phosphatase method for frozen sections, and the peroxidase-anti-peroxidase method for paraffin-embedded, formalin-fixed tissue sections. Fourteen hyperplastic human tonsils were used, and the results of the binding spectra of each lectin were compared. In general, the binding spectrum detected in the paraffin sections was part of the broader range of affinity obtained in the frozen sections. The lectin receptors on the cell surface were especially affected by formalin fixation. On the other hand, the paraffin sections, because of their superior morphology, showed a better localization of the cytoplasmic reaction product and discriminated the cell types more accurately. Thus, the two tissue preparations are rather complementary. In the tonsil peanut agglutinin (PNA) and periodic acid/Concanavalin A (PA/Con A) proved to be suitable tools for distinguishing exactly between the crypt and the surface epithelium. Ulex europaeus agglutinin I (UEA) is a reliable endothelial marker with a strong affinity to the crypt epithelium. In the frozen sections, PNA regularly stained follicular-centre cells on their cell surface. PNA, Helix pomatia agglutinin (HPA), soybean agglutinin (SBA) and Con A stained the histiocytic population, especially PNA which additionally stained an "asteroid" histiocyte. This cell probably corresponds to the antigen-presenting histiocyte of the T-system.