Electron microscope observations on Langerhans cells in the cervix

Immunological role of dendritic cells in cervical cancer

Cervical cancer is the second most frequent gynecological malignancy in the world. Human papillomavirus (HPV) infection is the primary etiologic agent of cervical cancer. However, HPV alone is not sufficient for tumor progression. The clinical manifestation of HPV infection depends also on the host's immune status. Both innate and adaptive immunity play a role in controlling HPV infection. In untransformed HPV-infected keratinocytes, the innate immunity is induced to eliminate the invading HPV pathogen through sensitization to HPV-related proteins by epithelial-residing Langerhans cells (LCs), macrophages, and other immune cells. Once the HPV infection escapes from initial patrolling by innate immunity, cellular immunity becomes in charge of killing the HPV-infected keratinocytes of the uterine cervix through systemic immune response developing by dendritic cells (DCs) in the regional lymphoid organs or through local immune response developing by LCs in the cervix. Thereby, DC/LC plays a critical role in eliciting innate and adaptive cellular immune responses against HPV infection. HPV-associated cervical malignancies might be prevented or treated by induction of the appropriate virus-specific immune responses in patients. Encouraging results from experimental vaccination systems in animal models have led to several prophylactic and therapeutic vaccine clinical trials.

Ultrastructural determination of gingival Langerhans cells in alloxan-induced diabetic rats

The ultrastructure of Langerhans cells has not been fully investigated in diabetes-associated gingival tissues. The present study was carried out to investigate the ultrastructure of gingival Langerhans cells in alloxan-induced diabetic rats. Gingival biopsies were obtained from 22 diabetic and 18 control rats. Langerhans cells were observed by transmission electron microscopy (TEM) in the basal layers of healthy oral epithelium. On rare occasions, Langerhans cells were found in the suprabasal layers of the oral epithelium. Langerhans cells in the oral epithelium of diabetic rats were seen in the basal and suprabasal layers. Usually, Langerhans cells had clear cytoplasm and convoluted or indented nuclei and few or no specific granules. The clear cytoplasm contained mitochondria, lysosomes and a small number of rough-surfaced endoplasmic reticulum regions, but it lacked tonofilament. Occasionally, centrioles were also observed in the cytoplasm. The membrane of Langerhans cells had no junctional complexes such as desmosomes. In diabetic rats, Langerhans cell precursors were developed into specific granule-bearing cells. Both Langerhans cells and their granules were more frequent in the gingiva of diabetic rats than in the control group. These data suggest that Langerhans cells play an important role in explaining the pathogenesis and development of diabetic gingivitis.

CD1a-positive infiltrating-dendritic cell density and 5-year survival from human breast cancer

Infiltrating CD1a(+) dendritic cells (DCs) have been associated with increased survival in a number of human cancers. This study investigated DC infiltration within breast cancers and the association with survival. Classical established prognostic factors, of tumour size, lymph node status, histological grade, lympho-vascular invasion, the KI-67 (MIB-1) fraction and the Nottingham Prognostic Index (NPI) were also compared. A total of 48 breast cancer patients were followed from the time of surgery and CD1a density analysis for 5 years or until death. Our data set validated previous studies, which show a relationship between survival and the NPI (P<0.001), tumour size (P<0.01) and lymph node status (P<0.05). Although more patients were alive at the 5-year time point in the group with higher CD1a DC density than the lower CD1a DC group, this failed to reach statistical significance at the P=0.05 level. Analysis at 10 years postsurgery is required to investigate the association further.

Immunohistochemical and ultrastructural study of Langerhans's cells in squamous cell carcinoma of the cervix

OBJECTIVE

To study Langerhans's cells (LCs) in cervical squamous cell carcinoma.

STUDY DESIGN

The study was carried out in the Shatby University Hospital, Alexandria, Egypt. Thirty cases with squamous cell carcinoma, 10 cases with cervical intra-epithelial neoplasia (CIN) and 10 cases with normal exocervix were recruited. Sections from the exocervix were stained with gold chloride, immunostaining with S-100 protein antiserum, adenosine triphosphatase ATPase and electron microscopy. Statistical evaluation was done using the t-test.

RESULTS

Gold chloride staining revealed significantly increased number of LCs in all cases of CIN compared to normal controls and with increasing grade of CIN (p < 0.001). No relationship between LCs number and the grade of carcinoma. Least branched LCs were predominant in the normal tissue while in neoplasia, these cells were of the most branched type, indicating a hyperactivity. S-100 protein positive LCs were almost absent in normal controls while their number were almost lower than the corresponding cases of CIN and invasive carcinoma after gold chloride or ATPase stainings. Signs of hyperactivity were evident in LCs of neoplastic cases after electron microscopy.

CONCLUSIONS

Proliferation and increased number of LCs in CIN is an immune response, while such reaction is suppressed by invasive carcinoma.

Localization of Simian immunodeficiency virus-infected cells in the genital tract of male and female Rhesus macaques

The SIV/Rhesus macaque model of HIV transmission has led to an increased understanding of the interactions between virus and host during the sexual transmission of HIV. SIV can be transmitted across the intact mucosa (stratified squamous epithelium) of the foreskin and glans of the penis of Rhesus macaques. SIV-infected cells can be found at all levels of the male Rhesus macaque reproductive tract and SIV can infect cells in the mucosal epithelium of the foreskin of the penis. SIV can be transmitted to female Rhesus macaques by infusing a cell-free virus suspension into the vaginal canal through a soft plastic pediatric nasogastric feeding tube. There does not appear to be any correlation between inoculation at any particular point in the menstrual cycle and the susceptibility of an animal to infection. Furthermore, the surgical removal of the cervix and uterus did not affect the dose of cell-free virus required for the genital transmission of SIV. Thus, target cells for SIV are present in the vaginal mucosa. In chronically-infected female Rhesus macaques, SIV-infected cells are present in the uterus, cervix and vagina. SIV-infected CD1a+ and p55+ Langerhans cells are also found within the stratified squamous epithelium of the vagina. Taken together these results are consistent with the hypothesis that the virus initially infects antigen-presenting cells in the vagina (macrophages and Langerhans cells) and then subsequent rounds of replication occur in the draining lymph nodes prior to spreading to more proximal lymphoid nodes and finally to the bloodstream and distant lymphoid tissue.

Immunization of the female genital tract with a DNA-based vaccine

Vaccines are being sought for contraception and the prevention of sexually transmitted diseases. However, progress is slow in this area largely because of lack of information on induction of protective immune responses in genital tract mucosa. In this study, we investigated whether in vivo transfection with a model DNA-based antigen delivered by gene gun technology would induce an antibody response detectable in vaginal secretions. Female rats were immunized with plasmids encoding human growth hormone (HGH) under the control of a cytomegalovirus promoter (pCMV/HGH) via vaginal mucosa (V), Peyer's patch (PP), and/or abdominal skin (S) routes. Localization of HGH in the target tissues demonstrated that all three sites can be transfected in vivo with pCMV/HGH. Vaginal tissues expressed roughly the same level of plasmid as skin. Antibodies to HGH were detectable in serum and vaginal secretions in rats immunized with pCMV/HGH. In the rats primed and boosted vaginally, vaginal immunoglobulin A (IgA) and IgG antibody titers to HGH were sustained for at least 14 weeks, whereas rats immunized via other routes and protocols (S/V, S/S, PP/PP, or PP/V) did not consistently sustain significant vaginal antibody titers beyond week 6. DNA-based immunizations administered by the gene gun may be an effective method of inducing local immunity in the female genital tract.

Cutaneous dendritic cells promote replication of immunodeficiency viruses

The cutaneous or mucosal DC-T cell environments seem extremely supportive of immunodeficiency virus replication. Apart from very early after SIV infection, similar virus producing cells have been difficult to detect in the lymphoid tissues where DCs and T cells are also known to interact. Large amounts of virus can be visualized in the germinal centers of the lymph nodes, much of which represents immune complexed virus that is trapped on the follicular dendritic cell surface. However, whether these virus-carrying cells actually make virus or even virus proteins requires further investigation. We believe that once an individual is systemically infected, free virus and/or virus-infected cells will seed peripheral tissues and when encountering similar DC-T cell environments as described in the oral mucosae, can set up sites of chronic virus replication. For instance, a virus-carrying T cell that migrates to the periphery would, on entering this milieu, interact with the mature DCs and activate virus production. This likely occurs at similar sites around the body, such as the mucosal associated lymphoid tissue of the gut, and is probably independent of the route of infection.

S100 positive dendritic cells in human lung tumors associated with cell differentiation and enhanced survival

Antigen presenting S100 positive dendritic cells have been quantified in normal trachea, lung, bronchial lymph nodes, 130 lung tumors and in 100 lymph nodes regional to tumor. Dendritic cells are rarely seen as intraepithelial components of the normal bronchial mucosa, but are more commonly observed in the perivascular lymphoid tissue of the submucosa and in the alveolar septae of normal lung parenchyma (6 +/- 4.85 cells/HPF). The density of these dendritic cells is marked in histologically normal bronchial lymph nodes. Bronchioalveolar (Alveolar II), well and moderately differentiated squamous cell carcinomas contain the highest density of S100 positive dendritic cells, while small cell lung cancer and poorly differentiated squamous cell carcinoma show the lowest density. Regional lymph nodes to lung tumors with lymphocytic predominance and active germinal centres show the highest density of dendritic cells, while unstimulated lymph nodes contain the lowest number of S100 positive dendritic cells. Tumor infiltrating lymphocytes are marked in and around lung tumors with the higher density of dendritic cells. Survival of patients whose tumors contain high density of S100 positive dendritic cells is more favourable compared to tumors with low density of these cells. It is concluded that the density of the antigen presenting S100 dendritic cells in lung tumors is related to subtype, and tumor differentiation. A high dendritic cell density is associated with enhanced patient survival.

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.

Density and distribution of Langerhans cells in the human uterine cervix

Using a combination of immunohistochemistry and planimetric observation we report the density and distribution of Langerhans cells (LCs) in epithelium from the normal ectocervix and from the normal transformation zone (TZ). The density of LCs increased towards the basement membrane. Dendritic LCs aspect was more prominent in the superficial layers.

Langerhans cell histiocytosis of the female genital tract

Langerhans cell histiocytosis (LCH) of the female genital tract is rare. Four new cases are reported, and there is a review of the 38 cases in the literature. This disease may involve the vulva, vagina, cervix, endometrium, and ovary. Four distinct patient groups, segregated on the basis of initial presentation and subsequent anatomic extent of disease, were categorized as follows: (1) "pure" genital LCH, (2) genital LCH with subsequent multi-organ involvement, (3) oral or cutaneous LCH with subsequent genital and multi-organ involvement, and (4) diabetes insipidus with subsequent genital and multi-organ disease. Although involvement of the genital tract can occur at any age, it is most common in young adulthood. Clinically, LCH may mimic either primary neoplasia or various inflammatory lesions; the major pathologic differential diagnosis is venereal and other inflammatory diseases. The pure genital form may have a distinct nosologic position in the spectrum of LCH similar to the "pure," self-limited cutaneous histiocytosis seen in infants. There is no correlation between histologic findings and the outcome of the genital lesions. There is also no correlation between clinical presentation and/or the extent of involvement and outcome of genital lesions; complete regression, partial improvement, persistent lesions, and recurrences were seen in all four groups of patients. The treatment of genital LCH is not well defined and is highly individualized. Therapy has included surgery, radiation, topical corticosteroids, topical nitrogen mustard, systemic chemotherapy, and combination therapy; mixed results were obtained with all treatment modalities. Although no modality has been shown to yield a superior outcome, complete surgical excision is advocated as initial therapy.

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.

An investigation of circulating and in situ lymphocyte subsets and Langerhans cells in the skin and cervix of patients with chronic renal failure

This study was designed to detect possible changes in the immunocytology of the human immune system in the skin, cervix and peripheral blood of patients with chronic renal failure (CRF) treated by conservative methods, haemodialysis (HD) and continuous ambulatory peritoneal dialysis (CAPD). In the skin, Langerhans cell numbers were reduced in CRF, CAPD and HD patients but in the cervix, Langerhans cells were reduced only in the CRF patients. There was a preponderance of T suppressor lymphocytes compared with T helper lymphocytes in the epidermis in the CRF and the CAPD groups. The presence of natural killer cells in the epidermis of the renal groups compared to controls was significant in the CRF and HD patients while the presence of T suppressor lymphocytes in the epidermis compared to controls was significant only in the CAPD patients. In the dermis, there was a mixed cellular infiltrate of T helper and T suppressor lymphocytes but with no subset attaining significance. The dermal infiltrate of T helper lymphocytes in all three groups of renal patients was significantly reduced compared to controls. In CRF patients, peripheral blood pan T cells, T helper and T suppressor lymphocytes and B lymphocytes were reduced, while T suppressor lymphocytes were reduced in both HD and CAPD patients, compared to controls. Though the results confirm alteration of the immunocytology of the skin, cervix and peripheral blood, we could not relate them to a clinical finding.

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.

Langerhans' cell density in the normal exocervical epithelium and in the cervical intraepithelial neoplasia

A morphometric analysis was performed of the Langerhans' cell density in epithelial sheets obtained from normal exocervices and from exocervices with squamous carcinoma. Laminae of exocervices with squamous carcinoma that showed cervical intraepithelial neoplasia (CIN) were classified according to its predominant degree of severity as CIN I, CIN II and CIN III or as normal when no neoplastic changes were found. Laminae with CIN showed a higher Langerhans' cell density than the laminae from normal exocervices and than the normal laminae of exocervices with carcinoma. The magnitude of the increase of Langerhans' cell density and the degree of severity of the neoplastic changes appear as closely related phenomena. An increase of the more ramified types of Langerhans' cell in the laminae containing CIN was found, with the most ramified being more frequent in the most severe lesions.

Quantitative assessment of Langerhans cells in actinic keratosis, Bowen's disease, keratoacanthoma, squamous cell carcinoma and basal cell carcinoma

The quantitative distribution of Langerhans cells (LC) was studied in a range of pre-neoplastic, in-situ and invasive neoplastic skin lesions using an antibody to S100 protein and the indirect immunoperoxidase technique. LC numbers were increased within the lesions of actinic keratosis, Bowen's disease, keratoacanthoma, squamous cell carcinoma and basal cell carcinoma. In all lesions except actinic keratosis the LC density was also significantly increased in the adjacent non-neoplastic epithelium. The increased LC density in neoplastic epithelium suggests either that LC are being retained within the abnormal epithelium for longer periods of time than normal or that increased numbers of LC are being actively attracted by factors produced by the neoplastic epithelium. While reduction of intraepithelial LC density may allow the initiation of neoplasia the increased density observed in this study suggests that at later stages of tumour growth LC may have a functional role in the host response to cutaneous neoplasia.

The effect of atrophy, hyperplasia, and keratinization accompanying the estrous cycle on Langerhans' cells in mouse vaginal epithelium

The morphology and numbers of Langerhans' cells vary in epithelia with different patterns of hyperplasia and keratinization. Langerhans' cells stained for ATPase were compared at five phases of the estrous cycle in murine vaginal epithelium. The cells were more dendritic and sparsely distributed with hyperplasia and were less dendritic and more densely distributed with atrophy. Greater numbers of the cells did not accompany keratinization at estrus. Ultrastructurally, three types of Langerhans' cells were discriminated. The first type, active in protein synthesis and phagocytosis, was commonest in sloughing and atrophic epithelium. The second type, containing accumulated and dispersed, electron-dense bodies presumed to be lysosomes, predominated in hyperplastic epithelium. The third, a mature resting cell, was found only after keratinization was complete. This study shows that Langerhans' cells in murine vaginal epithelium vary in morphology and numbers with the epithelial changes of the estrous cycle which may relate to their immunological role, but does not support the contention that their distribution is important for keratinization.

S-100 protein-positive Langerhans cells in various human lung cancers, especially in peripheral adenocarcinomas

The appearance of S-100 protein-positive Langerhans cells was studied in 90 cases of various lung cancers by an immunohistochemical method. S-100 protein-positive dendritic cells were frequently observed in many adenocarcinomas, especially in those subclassified as bronchiolar cell or type II alveolar cell type. However, no S-100 protein-positive cells were found in "goblet cell type" adenocarcinoma. In some cases of squamous cell carcinoma and large cell carcinoma, these dendritic cells were also observed though they were fewer in number. In all cases of small cell carcinoma, however, S-100 protein-positive dendritic cells were rare. Electron microscopic study of two adenocarcinomas clearly demonstrated many Birbeck granules in the cytoplasm of S-100 protein-positive dendritic cells and confirmed that S-100 protein-positive cells in lung cancer were identical with Langerhans cells.

Ultrastructural identification of Ia positive dendritic cells in the lactating rat mammary gland

Dendritic cells which express Ia antigen have been demonstrated for the first time in the lactating rat mammary gland. Ultrastructurally, the dendritic cells appear as electron-lucent pale cells interspersed among the epithelial cells of the alveoli, forming a cell population distinct from classical macrophages. They show morphological resemblance to the dendritic cells of lymphoid organs as well as the Langerhans cells of skin. The Ia antigen has been localised by electron microscopic immunocytochemistry on the cell membrane and endocytotic vesicles and tubules. Ia positive cells are also seen in the stroma of the mammary gland. It is proposed that the dendritic cells of the mammary gland belong to the lineage of epidermal Langerhans cells and lymphoid dendritic cells, subserving an immunological role in the lactating breast.

Langerhans cells: antigen presenting cells of the epidermis

While epidermis in the skin provides an excellent barrier to the environment, it is an incomplete one. Some antigenic material can penetrate through the stratum corneum (or be introduced pathologically) where strategically placed epidermal Langerhans cells reside. In this review, we have assembled relevant data concerning the antigen presenting potential of epidermal Langerhans cells. Strong circumstantial evidence derived from in vitro studies of epidermal cell suspensions enriched for Langerhans cells indicates that Langerhans cells possess this capability. In vivo studies with intact skin indicate that critical numbers of functioning Langerhans cells are essential for successful induction of contact hypersensitivity by epicutaneously applied haptens. And within the past several months, experiments with purified preparations of epidermal Langerhans cells have proven that these cells, and perhaps they alone among epidermal cells, possess the capacity of processing and presenting haptenic determinants to the immune system. The challenge for the future is to determine the extent to which this unique property of Langerhans cells affords physiologic protection to the skin and under what pathologic circumstances altered Langerhans cell function leads to disease.

Cervical healing and Langerhans' cells

A study of cervical epithelium healing after laser treatment found the early presence of Langerhans' cells. These cells were demonstrated using a histochemical technique for adenosine triphosphatase. The significance of Langerhans' cells in healing epithelium and their probable immunological role is discussed.

Healing of cervical epithelium after laser treatment of cervical intraepithelial neoplasia

The recognition that only a minority of cervical premalignant lesions progress to invasion, and the increasing incidence of these lesions in young women, has led to a more conservative approach in the treatment of cervical intraepithelial neoplasia. One such method uses the carbon dioxide laser but inadequate length of follow-up has prevented a prediction of risk of recurrence. Observations made in this study on the speed of healing, source of new epithelium, maturation of the epithelium and the absence of herpes nucleic acid suggest that this risk is low.

Langerhans cells in squamous exocervical carcinoma: a quantitative and ultrastructural study

The gross morphology, density, distribution, and ultrastructure of the Langerhans cell (LC) in the human exocervix in cases of cervical intraepithelial neoplasia (CIN) and incipient carcinoma were investigated. Two zinc-iodide-osmium (ZIO) procedures were applied to epithelial sheets and to tissue sections for light and electron microscopy. The ZIO methods as well as conventional electron microscopy revealed the presence of LCs in CIN, in the invasive prongs, and in the lymphoid infiltrate of the chorion. The epithelial sheets demonstrated a LC density 3.5 times higher than we have previously reported for the normal exocervix. The region around the external os displayed the highest LC density and the most advanced grades of CIN. The LCs were classified into six types according to the number of processes and secondary branches. The most ramified types were more abundant in the neoplastic exocervix than in the normal exocervix. The LC in all locations of the exocervix with carcinoma showed hypertrophy of the rough and smooth endoplasmic reticula and a large number of filaments. The RER displayed dilated cisternae containing electron-dense material. Specialized contacts between LCs and lymphocytes were an outstanding finding. These findings suggest that the LC might play an important role in the neoplastic process.

Langerhans' cells in human cervical epithelium: an immunohistological study

Langerhans' cells are intraepithelial dendritic cells believed to be important in the recognition and processing of exogenous antigens. They were demonstrated by immunohistological methods in cervical tissue obtained from 10 subjects ranging in age from 30 weeks gestational age to 62 years. Langerhans' cells were clearly delineated in all tissue sections and appear to form a relatively constant component of both the transformation zone and ectocervical epithelium. In addition to Langerhans' cells, a population of T lymphocytes characterized as predominantly T-cytotoxic/suppressor cells have also been demonstrated. The interaction between Langerhans' cells, T lymphocytes and stromal macrophages and their relation to antigen recognition is discussed.

Lymphocytes and Langerhans cells in the human oesophageal epithelium

Using monoclonal antibodies on fresh frozen endoscopically obtained oesophageal biopsies the distribution of Langerhans cells, B lymphocytes, and various subpopulations of T lymphocytes was studied in the normal human oesophageal mucosa and in oesophagitis. Identification of the lymphocytes was carried out by an immunoperoxidase technique using OKT3 (antihuman T cell antibody), OKT4 (antihuman helper T cell antibody), OKT8 (antihuman cytotoxic T cell) and OKT10 (antihuman null cell antibody). Identification of the Langerhans cells was carried out using an ATPase stain and OKIa (Ia like antigen) and OKT6 (antihuman thymocyte). In the normal oesophageal epithelium cytotoxic T lymphocytes are found as well as Ia positive Langerhans cells. Helper T lymphocytes and B lymphocytes are present mainly in the lamina propria. In oesophagitis an increase in Langerhans cells and cytotoxic T lymphocytes within the epithelium is found. From these findings it can be concluded that the oesophagus contains a reticuloepithelial system as well as a lymphocytic population which are a part of the gut-associated lymphoid tissue.

Langerhans cells of the ocular surface

Recent evidence has been collected by several investigators defining a distinct population of dendritic cells (Langerhans cells) of mesenchymal origin residing in the epidermal surfaces of many mammalian species. These cells play a dominant role in the processing of antigens presented through cutaneous surfaces and carry a Class II histocompatability antigen felt to be of central importance in the afferent arm of allograft rejection. They also possess many of the characteristics of macrophages active in the efferent arm of immunologic responses. An equivalent subset of dendritic cells (Langerhans cells) in ocular surface epithelium of the human, mouse rat, and guinea pig has been identified by enzyme histochemistry, immunofluorescence, and electron microscopy. Ocular surface Langerhans cells proliferate in the setting of corneal inflammation (remote and recent) and are depleted by topical and systemic corticosteroids. Ocular surface Langerhans cells may play a central role in ocular contact hypersensitivity, corneal allograft rejection, and ocular surface immune surveillance.

Langerhans cells among bile duct epithelial cells in chronic liver disease

Langerhans cells were found among bile duct epithelial cells in a biopsy specimen from a patient with chronic liver disease showing cholangitic features. The bile duct was 90 micrometers in diameter and surrounded with mononuclear cell infiltration. Under the electron microscope, the cell had a clear cytoplasm and contained a deeply indented nucleus, a centriole, well-developed Golgi complexes and many rod-shaped bodies (Birbeck granules).

Langerhans cells in dermoid cysts: transmission electron microscopic, cytochemical and immunofluorescent observations

Langerhans cells were detected in squamous, stratified epithelia lining human dermoid cysts. Their presence was assayed by ATPase staining and reactivity with heteroantisera against "Ia-like" antigens. Transmission electron microscopic studies demonstrated variations in the numbers of cells showing Birbeck granules in epithelia with different degrees of keratinization. Indeterminate cells (i.e. lacking granules), were more frequent in epithelia showing combined mucous and keratinizing differentiation. Membrane-coating-granules and keratohyalin granules were present in epithelia containing Langerhans cells with clearly identifiable Birbeck granules. Interepithelial mast cells were observed in epithelia with mucous differentiation. A relationship between Langerhans cells and keratinization was suggested. Such non-immune functions are compatible with the known macrophage characteristics of the cell.

Langerhans' cells in a pleomorphic adenoma of submandibular salivary gland

Large numbers of round and dendritic cells similar to Langerhans' cells of normal epidermis and other epithelia were seen within a pleomorphic adenoma of the submandibular salivary gland. These cells, which were present only in areas of non-cornifying epidermoid metaplasia, exhibited Birbeck granules with isolated terminal vesicles, cytoplasmic microfilaments, microtubules, and a few poorly developed intercellular junctions.

The Langerhans cell density of palatal epithelium in denture and non-denture wearers, as correlated with other parameters of the palatal mucosa

A quantitative histological investigation was carried out on biopsy specimens taken from patients suffering from denture sore mouth. The results were compared with those obtained in investigations on denture and non-denture wearers. The sections were studied by standardized quantitative morphometric methods. After 4 years the denture bearing palatal epithelium from both groups, normal denture wearers and the patients suffering from denture sore mouth did not show changes in mean thickness of the epithelium as compared with the controls. The mitotic index in denture bearing epithelium from patients suffering from denture sore mouth was three times lower than in the epithelium of the normal denture wearers. The number of Langerhans cells correlated with the mitotic indices of the group of denture wearers and non-denture wearers. The group of denture sore mouth patients showing a low mitotic index showed a high number of Langerhans cells in their palatal epithelium. The three groups of patients investigated did not show differences in density of mast cells in the lamina propria of their palatal epithelium.

Dense bodies and Langerhans granules after application of podophyllum resin

The application of an alcoholic solution of podophyllum resin at concentrations above 10% for seven hours on guinea-pig udders increases the number of dense intracytoplasmic bodies in the Langerhans cells localized in the epidermis. A close relationship can be established between these inclusions and the typical Langerhans granules in view of the numerous intermediate forms with features of one or the other. Serial sections of these structures confirm the irregularity not only of the lysosome-like bodies but also of the Langerhans granules, which may be fusiform or oblong or even present two vesicular dilatations, one at each end of the rod.