Epithelial dendritic cells in pathological human oral tissues

Expression of CD1a by Langerhan's Cells in Oral Lichen Planus - A Retrospective Analysis

INTRODUCTION

Langerhan's Cells (LCs) are dendritic cells of the oral epithelium which play a role in a series of oral lesions from gingivitis to oral cancer. Oral Lichen Planus (OLP) is an oral mucosal T-lymphocyte mediated immunologic reaction to an unidentified putative antigen or allergen.

AIM

The aim of this study was to quantify the presence of immature LCs in OLP comparing them with normal epithelium.

MATERIALS AND METHODS

A retrospective study using 30 of OLP cases were conducted. Immunohistochemistry was performed using polyclonal anti-CD1a antibodies to identify LCs in 10 cases of normal tissue and 30 samples of OLP. The distribution of LCs among lesional tissue and normal mucosa was analysed using Mann-Whitney U test.

RESULTS

LC population in OLP was significantly higher when compared to the normal epithelium (p<0.001).

CONCLUSION

The increase in LCs indicates the active role played during the antigen detection in OLP and subsequent presentation to T-lymphocytes.

A Comparative Immunohistochemical Analysis of Langerhans Cells in Oral Mucosa, Oral Lichen Planus and Oral Squamous Cell Carcinoma

BACKGROUND

Langerhans cells (LCs) are immunocompetent cells resident within oral mucosa which, together with intraepithelial lymphocytes, play a role in mucosal defence. LCs play a role in the pathogenesis of Oral lichen planus (OLP), a chronic mucocutaneous disorder thought to result from cell-mediated immune damage. In oral squamous cell carcinoma (OSCC), LCs are thought to present tumour antigens to the lymphocytes.

AIM

To assess and compare LCs immuno-histochemically in normal mucosa, oral lichen planus and oral squamous cell carcinoma using anti S100 antibody and to know whether LCs play any role in local immune response to these diseases.

MATERIALS AND METHODS

The study was carried out in 65 cases (study group), 30 oral lichen planus and 35 oral squamous cell carcinoma (15 well differentiated, 14 moderately differentiated and 6 poorly differentiated), that were randomly selected from the archives of department of oral pathology and along with control group consisting of 30 normal healthy mucosa. The tissue sections were stained immunohisto-chemically by using anti S100 antibody in each group for detection of LCs.

RESULTS

There was significant change in mean value of number of LCs in the study groups i.e. OLP and OSCC when compared to that of control group. The results of our study also revealed that there was decrease in the mean value of langerhans cells as the tumour progressed from well differentiated squamous cell carcinoma to poorly differentiated LCs carcinoma.

CONCLUSION

A better understanding and clarity of LCs is pivotal for designing novel or improved therapeutic approaches that will allow proper functioning of LC's in patients with OLP and OSCC, thus significantly reducing the morbidity of OLP and OSCC patients.

Association between langerhans cells population and histological grade of oral squamous cell carcinoma

Context:

Langerhans cells (LCs) are a unique population of antigen processing cells in the epidermis and mucous membrane, which may play a role in the defence mechanism against epithelial tumors.

Aims:

To compare the distribution of LCs in oral squamous cell carcinomas (OSCC) and normal oral epithelium; and to determine whether the population of LCs in OSCC has any correlation with histological grading of these malignancies.

Settings and Design:

A cross-sectional immunohistochemical analysis of OSCC cases.

Materials and Methods:

Forty-eight randomly selected paraffin tissue blocks of OSCC cases and 30 cases of normal oral epithelium were included. Hematoxylin and eosin-stained sections of the OSCC cases were reviewed and categorized as high-grade malignant tumors or low-grade malignant tumors. Tissue sections were analyzed for density of LCs using CD1a antibody expression.

Statistical Analysis Used:

Data are expressed as percentages compared by Chi-square statistics; mean ± standard deviation, compared by Mann-Whitney-U test and Spearman's correlation tests.

Results:

LCs population was significantly higher in normal oral epithelium when compared with OSCC cases (P = 0.001). There was also a significant difference in the number of LCs per millimetre square area of tissue section between well-differentiated tumors and poorly-differentiated tumours (P = 0.03). There was a negative correlation between the population density of LCs and the grade of OSCC.

Conclusions:

These findings suggest that oral mucosal LCs are involved in immune-surveillance and immunologic impairment may characterize invasive OSCC. In addition, LCs density characterizes histological grades of OSCC, which may be of a prognostic value.

Langerhans cells and T cells sense cell dysplasia in oral leukoplakias and oral squamous cell carcinomas--evidence for immunosurveillance

Leukoplakias (LPLs) are lesions in the oral mucosa that may develop into oral squamous cell carcinoma (OSCC). The objective of this study was to assess presence and distribution of dendritic Langerhans cells (LCs) and T cells in patients with LPLs with or without cell dysplasia and in oral squamous cell carcinoma (OSCC). Biopsy specimens from patients with leukoplakias (LPLs) with or without dysplasia and oral squamous cell carcinoma (OSCC) were immunostained with antibodies against CD1a, Langerin, CD3, CD4, CD8 and Ki67, followed by quantitative analysis. Analyses of epithelium and connective tissue revealed a significantly higher number of CD1a + LCs in LPLs with dysplasia compared with LPLs without dysplasia. Presence of Langerin + LCs in epithelium did not differ significantly between LPLs either with or without dysplasia and OSCC. T cells were found in significantly increased numbers in LPLs with dysplasia and OSCC. The number of CD4+ cells did not differ significantly between LPLs with and without dysplasia, but a significant increase was detected when comparing LPLs with dysplasia with OSCC. CD8+ cells were significantly more abundant in OSCC and LPLs with dysplasia compared with LPLs without dysplasia. Proliferating cells (Ki67+) were significantly more abundant in OSCC compared to LPLs with dysplasia. Confocal laser scanning microscopy revealed colocalization of LCs and T cells in LPLs with dysplasia and in OSCC. LCs and T cells are more numerous in tissue compartments with dysplastic epithelial cells and dramatically increase in OSCC. This indicates an ongoing immune response against cells with dysplasia.

Detection of fascin and CCR-7 positive mature dendritic cells in oral lichen planus

BACKGROUND

Dendritic cells (DC) play a crucial role in the pathogenesis of oral lichen planus (OLP) with respect to antigens presented to T cells. We performed immunohistochemical analysis to elucidate the process of activation of DC in OLP.

METHODS

Thirty biopsy specimens were obtained from the patients with OLP. The expressions of CD1a, Langerin, S-100, fascin, chemokine receptor-7 (CCR-7), D2-40, cyclooxygenase-2 (COX-2), and microsomal prostaglandin E synthase-1 (mPGES-1) in DC from OLP and disease free control were investigated using specific antibodies. The distribution and number (1 mm(2)) of DC were assessed in the intra-epithelium and the submucosa specimens. Correlation between the number of DC and epithelium thickness was also determined.

RESULT

Immature DC (Langerin(+), CD1a(+), and S-100(+)) were identified in the epithelia from OLP patients and control, though the numbers of Langerin(+) and CD1a(+) positive cells were decreased in the OLP samples as compared to the control. Mature DC (fascin(+)) were identified in the submucosa specimens, not found in the epithelium from OLP or control. Double immunostaining revealed DC positive for fascin and CCR-7 in the submucosa, which had migrated into D2-40(+) lymph vessels. Furthermore, keratinocytes expressed both Prostaglandin E(2) (PGE(2)) converting enzymes, COX-2, and mPGES-1, indicating PGE(2) synthesis in the epithelial layer of the OLP specimens.

CONCLUSION

Our results indicate that DC change from immature to mature in the epithelium and are then drawn out to the submucosa. We demonstrate that mature DC localized in the submucosa, it consequently migrates into lymph vessels. This maturation process of DC is an important immunopathological feature of OLP.

CD40 in human oral epithelia

CD40 is a transmembrane glycoprotein belonging to the tumour necrosis factor receptor superfamily, which has a role in a number of biological functions, including the regulation of cell growth and division, and cell mediated immunity. Although originally described on leucocytes, principally B lymphocytes, there is now abundant evidence for the cellular diversity of CD40. The aim of this article is to review the available data on CD40 in oral epithelium, principally that lining the oral mucosa, but also that of the salivary glands.

Oral lichen planus: immunohistology of mucosal lesions

BACKGROUND

Current evidence suggests that immunological mechanisms are involved in oral lichen planus (OLP) pathogenesis. The events implicate activated epithelia that comprise antigen-presenting Langerhans cells, immunocompetent keratinocytes and subepithelial inflammatory infiltrate. Also, the presence of a high density of leucocyte cells may occur for the expression of a variety of adhesion molecules. The aim of this study was to analyse the immunoexpression of some adhesion molecules as well as lymphocytic markers in order to determine the disease pathogenesis in a Venezuelan population.

METHODS

The 18 OLP and 10 normal oral mucosa biopsies were immunostained for CD4, CD8, CD1a, LFA-1, VCAM-1 and ICAM-1.

RESULTS

The results showed an increased number of CD4+, CD8+, CD1a+ cells in OLP. Serial sections showed CD4+ and CD8+ cells also expressed LFA-1. The expression of ICAM-1 and VCAM-1 were significantly higher in OLP.

CONCLUSIONS

The immunological reaction begins with Langerhans cells activation, which presents an antigen to CD4+ lymphocytes. Those cells through ICAM-1 and LFA-1 promote epithelial destruction. Afterwards, cytokine production, ICAM-1 and VCAM-1 expression can activate CD8+ lymphocytes leading to the chronic form of the disease.

CD1a-positive cells in odontogenic cysts

Langerhans cells (LC) are bone marrow-derived cells that have a CD1a-positive immunophenotype and are an important portion of the cell-mediated immune response. The aim of this study was an immunohistochemical evaluation of CD1a positive cells in different types of oral cysts. Fifty-five cysts were studied: 18 odontogenic keratocysts (OKC), of which five were orthokeratotic and 13 parakeratotic; 19 radicular cysts; and 18 dentigerous cysts. Positive LC was 80% for orthokeratotic OKC, 33% for parakeratotic OKC, approximately 35% for radicular cysts, and approximately 20% for dentigerous cysts. The results show that OKC with well-differentiated epithelial linings presented a greater number of LC than the other cysts. However, when the cyst wall was inflamed there were no differences in LC expression in the different types of cysts. The data confirm that LC distribution seems to be associated with the degree of differentiation of the epithelia.

Quantitative morphological analysis of Langerhans cells in healthy and diseased human gingiva

Langerhans cells (LC) are implicated in the initiation and maintenance of inflammatory periodontal diseases. The purpose of this immunohistological study using morphometric and automated image analysis was to determine the morphological features of CD1a+ LC in healthy and inflammatory gingiva according to their localisation in the upper epithelium or the basal layer. The study was on gingival samples from 11 healthy controls (C), eight patients with gingivitis (G) and 12 patients with severe chronic adult periodontitis (P). The results show that in the basal layer of all experimental groups, the perimeter, surface and equivalent diameter of CD1a+ LC were significantly decreased (P<0.005) when compared with those in the upper epithelium of the same group. Furthermore, CD1a+ LC had become more rounded, reflected by a significant increase in form factor (P<0.005), when located close to the epithelial basal membrane. In the upper epithelium of group P, the perimeter, surface and equivalent diameter of CD1a+ LC were significantly decreased (P<0. 05) and the form factor significantly increased (P<0.05) when compared with the upper epithelium of group C. This work provides evidence for important morphological variations in CD1a+ LC according to their location within the epithelium and the severity of the periodontal disease. The observed morphological changes may reflect a cellular adaptation during the epithelial transmigration and could eventually be involved in immune stimulation during periodontitis.

Update on oral lichen planus: etiopathogenesis and management

Lichen planus (LP) is a relatively common disorder of the stratified squamous epithelia, which is, in many ways, an enigma. This paper is the consensus outcome of a workshop held in Switzerland in 1995, involving a selection of clinicians and scientists with an interest in the condition and its management. The oral (OLP) eruptions usually have a distinct clinical morphology and characteristic distribution, but OLP may also present a confusing array of patterns and forms, and other disorders may clinically simulate OLP. Lesions may affect other mucosae and/or skin. Lichen planus is probably of multifactorial origin, sometimes induced by drugs or dental materials, often idiopathic, and with an immunopathogenesis involving T-cells in particular. The etiopathogenesis appears to be complex, with interactions between and among genetic, environmental, and lifestyle factors, but much has now been clarified about the mechanisms involved, and interesting new associations, such as with liver disease, have emerged. The management of lichen planus is still not totally satisfactory, and there is as yet no definitive treatment, but there have been advances in the control of the condition. There is no curative treatment available; immunomodulation, however, can control the condition. Based on the observed increased risk of malignant development, OLP patients should be offered regular follow-up examination from two to four times annually and asked to report any changes in their lesions and/or symptoms. Follow-up may be particularly important in patients with atrophic/ulcerative/erosive affections of the tongue, the gingiva, or the buccal mucosa. Much more research is required into the genetic and environmental aspects of lichen planus, into the premalignant potential, and into the possible associations with chronic liver, and other disorders. More clinical studies are required into the possible efficacy of immunomodulatory drugs such as pentoxifylline and thalidomide.

Expression of CD1 and HLA-DR by Langerhans cells (LC) in oral lichenoid drug eruptions (LDE) and idiopathic oral lichen planus (LP)

Numbers of Langerhans cells (LC) expressing the common thymocyte antigen (T6/CD1) are similar in oral lichen planus (LP) and in normal oral epithelium; however, expression of class II major histocompatibility antigens (HLA-DR/Ia) by Langerhans cells is greater in lichen planus than in normal epithelium, a phenomenon believed to be associated with activation and antigen presentation. This study quantified the numbers of T6+ve and HLA-DR + ve Langerhans cells in oral lichen planus and lichenoid drug eruptions (LDE) to investigate whether differences may reflect differing routes of antigen presentation. Six patients with oral lichenoid drug eruptions and six control idiopathic oral lichen planus patients had lesional biopsies. An immunoperoxidase technique was used to demonstrate binding of T6 and HLA-DR antibodies to identify dendritic intraepithelial cells as Langerhans cells and activated Langerhans cells, respectively. In lichenoid drug eruptions, the number of HLA-DR + ve LC was significantly lower than the number of T6 + ve LC (P < 0.05), whereas in idiopathic lichen planus the numbers of T6 + ve and HLA-DR + ve LC did not differ significantly (P = 0.20). The results provide evidence for differences in the routes of antigen presentation in lichenoid drug eruptions and idiopathic lichen planus.

Immunologic aspects of dermal and oral lichen planus: a review

There have been many investigations, both experimental and epidemiologic, of the forms of LP affecting the skin and oral mucosae. These studies have provided a varied range of hypotheses to explain not only the factors determining susceptibility to and onset of this disease, but also the immunologic mechanisms leading to the pathosis with which LP is associated. Much progress has been made, especially through in vitro studies, regarding detailed aspects of the immunology of LP. However, data is often conflicting or incomplete. In this review we attempt to bring together the currently available data regarding the immunologic basis of LP.

Oral mucosal Langerhans' cells

Langerhans' cells (LC) are dendritic, antigen-presenting cells present within the epithelium of skin and mucosa, including that of the oral cavity. This article reviews the literature on the phenotypic and functional features of oral mucosal Langerhans' cells, and speculates on other aspects by extrapolating from data on their epidermal counterparts.

Expression of lymphocyte function-associated antigen 3 in oral lichen planus

OBJECTIVE

The expression pattern of lymphocyte function-associated antigen 3 (LFA-3) in the buccal mucosa of oral lichen planus (OLP) patients was compared to that of healthy controls to investigate the possible role of LFA-3 in cell interactions within OLP lesions.

MATERIALS AND METHODS

Samples of buccal mucosa from 17 clinically healthy individuals and 17 OLP lesions were analysed. Expression of LFA-3, CD2, CD3 and CD14 was visualized by an immunoperoxidase technique and assessed microscopically.

RESULTS

In healthy buccal mucosa LFA-3 was expressed on keratinocytes, Langerhans cells within the epithelium and on endothelial cells in the lamina propria. In OLP patients a similar pattern of LFA-3 staining was observed. In addition, cytoplasmic LFA-3 without accompanying surface staining, was seen on a subpopulation of macrophage-like cells. Substantial amounts of LFA-3 also appeared to be associated with non-cellular components of the extracellular matrix within the inflammatory infiltrate.

CONCLUSIONS

We have obtained evidence for a previously undescribed localization of LFA-3 within macrophages, and have observed that expression of LFA-3 is apparently elevated within OLP lesions. LFA-3 may play an important role in the pathogenesis of OLP.

Lack of correlation between DNA ploidy, Langerhans cell population and grading in oral squamous cell carcinoma

This study was undertaken to determine the inter-observer reproducibility of the invasive cell grading method on oral squamous cell carcinomas and to correlate this with the DNA ploidy status and Langerhans cell (LC) population. Fifty formalin-fixed paraffin-embedded blocks that contained both tumor and adjacent normal epithelium were randomly selected. DNA ploidy analysis was performed on a flow cytometer and the LC population was determined using an immunohistochemical technique with anti-S100 and anti-HLADR primary antibodies. The inter-observer correlation of the total malignancy score and individual morphologic features was highly significant. Thirty-two of the 50 tumors were graded as poorly differentiated and 18/50 as moderately differentiated. Thirteen of 25 poorly differentiated tumors had an aneuploid DNA content compared with 9/18 of the moderately differentiated group. No statistical differences in the LC counts between the poorly and moderately differentiated and aneuploid and diploid carcinomas were found. This study showed that the invasive cell grading method is reproducible but no correlation was found between the grading results and the ploidy status or LC count.

Human oral mucosal melanocytes: a review

Despite the complex role of melanocytes in skin physiology, the function of oral mucosal melanocytes has attracted little research interest and remains largely unclear. This article reviews what is known about oral mucosal melanocytes and identifies areas of research that may shed further light on their role in oral biology.

Langerhans cell density in normal human oral mucosa and skin: relationship to age, smoking and alcohol consumption

The immune function of skin has been studied extensively and it has been suggested that epidermal Langerhans cell (LC) density and function decreases with increasing age. Little is known, however, about the effect of age on oral mucosal LC. Cryostat sections from biopsies of buccal mucosa, lip, hard palate, lateral border of tongue, floor of mouth and abdominal skin, obtained from 91 subjects (aged 16-96 yr), were reacted immunocytochemically with a monoclonal antibody against CD1a and then LC density was expressed as LC/mm epithelial surface length. No significant effect of age on mucosal or skin LC density was found, whilst a history of smoking was associated with an increase in LC density in lateral border of tongue and in biopsies of labial mucosa taken from men (P < 0.05). There was no significant difference between LC density in men and women in oral mucosa. Oral mucosal LC may therefore form a relatively stable population in the adult and thus the increased incidence of mucosal disease in the elderly may be the result of subtle changes in cell mediated immune function rather than changes in LC density.

Hg-provocation of oral mucosa in patients with oral lichenoid lesions

Five amalgam-bearing patients, with clinically and histologically confirmed oral lichenoid lesions, were tested by applying 0.5% Hg in petrolatum for 10 min to clinically normal mucosa. Control sites were exposed to petrolatum only. Four amalgam-bearing patients with no clinical evidence of oral lichenoid lesions served as controls; they were subjected to similar Hg and petrolatum exposure. After 24 h, biopsies were taken and immunocytochemically analyzed with monoclonal antibodies to lymphoid and nonlymphoid cells. No distinct differences could be detected between the Hg-exposed areas of the lichen patients and those of the nonlichen patients. Furthermore, normal mucosa exposed to petrolatum only showed a staining pattern in the lichen patients which was no different from the nonlichen patients. The findings are discussed with respect to possible mechanisms of development of lichen-like lesions in oral mucosa.

Langerhans cells: structure, function and role in oral pathological conditions

Langerhans cells (LCs) are dendritic bone marrow derived cells situated suprabasally in most stratified squamous epithelia, such as the epidermis and the epithelium of oral mucosa, including the gingiva. Langerhans cells are thought to act as antigen-presenting cells (APC) during induction of immune responses. The exact role of Langerhans cells in the oral mucosa is not fully understood although several investigations suggest that these cells are involved in reactions to antigen challenge under both normal and pathological situations. In this paper the structure, phenotypic markers and derivation of Langerhans cells are reviewed. In view of recent findings, the immunological characteristics and the implications of Langerhans cells in pathologic oral reactions are discussed.

Langerhans cell distribution and keratinocyte expression of HLADR in oral lichen planus

Keratinocyte expression of the Class II major histocompatibility complex antigen HLADR, is seen in several inflammatory disorders of skin and mucosa, including lichen planus. The purpose of this study is to determine whether the distribution of Langerhans cells and their expression of CD4 in oral lichen planus is related to keratinocyte HLADR. The numbers of CD1- and CD4-positive Langerhans cells were compared in areas of keratinocyte HLADR and areas showing no expression in oral lichen planus and with normal oral mucosa. Cells were identified using an immunoalkaline phosphatase technique and numbers were expressed per mm epithelial surface length. In lichen planus, an increase both in the number of Langerhans cells and the numbers expressing CD4 were found in areas of keratinocyte HLADR expression compared with HLADR negative areas and with normal oral mucosa. There was no difference in the numbers of Langerhans cells or their expression of CD4 between HLADR-negative areas in LP and normal oral mucosa. These results show that the distribution of Langerhans cells is related to keratinocyte expression of HLADR and suggest that Langerhans cell entry may be enhanced in these areas. Whilst it is possible this enhancement is mediated by CD4/HLADR interaction, other molecules are also likely to be important in controlling Langerhans cell entry into oral mucosa.

Loss of epithelial L1 expression is associated with cellular invasion of oral squamous cell carcinomas

Recent studies have suggested that the epithelial expression of two leukocyte-related proteins, human class II HLA-DR antigen and myelomonocytic L1 antigen, depends on a certain state of cellular maturation and differentiation. We have studied HLA-DR and L1 expression in oral squamous cell carcinomas. The epithelial distribution of these proteins was evaluated in relation to differentiation alterations by two-color immunofluorescence staining with cytokeratins (K14 and K13) as a baseline. HLA-DR was infrequently expressed in oral carcinomas, apparently being unrelated to the degree of differentiation and the subepithelial leukocyte infiltration. L1 was generally present in oral epithelium but disappeared in the most invasive cells of carcinomas. These cells were also K14 and K13 negative suggesting an abnormal state of differentiation. L1 has been suggested to have an inhibitory effect on casein kinases I and II, enzymes possibly associated with cell proliferation; it might therefore exert an inhibitory effect on tumor growth. Its absence could be an interesting aspect of the invasiveness of oral carcinoma cells.

Reduction of Langerhans cells in smokeless tobacco-associated oral mucosal lesions

Localized absence of epithelial Langerhans cells (LC) has been shown to affect systemic immune responses, allow microbial colonization and play a possible role in carcinogenesis. Because use of smokeless tobacco is associated with abnormal oral mucosal changes and development of carcinoma, we examined lesion and control specimens from 17 current users of smokeless tobacco to determine whether lesions showed changes in LC number or antigen expression. We identified LC by immunohistochemistry with antibodies to the antigens T6, HLA-DR, HLA-DQ, and HLA-DP. Lesion specimens contained fewer LC (means of 6 LC/mm and 10 LC/mm2) than did the corresponding control specimens (means of 14 LC/mm and 30 LC/mm2), and in each pair of lesion and autologous control specimens the reduction in LC was on average 58% (range, 3% to 95%). There were no apparent differences between lesion and control specimens in the number of LC expressing each of the four marker antigens. Reductions in LC occurred in all types of smokeless tobacco-associated lesions, regardless of increased epithelial thickness or changes in keratinization. Our data indicate that smokeless tobacco reduces the number of Langerhans cells at its site of contact with the oral mucosa.

Oral lichen planus. A review

Lichen planus is a mucocutaneous disease of unknown etiology which, according to current knowledge, may represent a cell-mediated immunological response to induced antigenic changes in the skin and mucosa. Oral lichen planus (OLP) is a disease of adulthood and as one of the most prevalent diseases affecting the oral mucosa it has been the subject of intensive research during recent years. Ultrastructural and immunohistochemical studies particularly dealing with the subepithelial inflammatory cell infiltrate and its relations to epithelial pathology, the basal cell region and the intraepithelial antigen presenting Langerhans' cells, have contributed vastly to our knowledge of the pathogenesis of OLP. However, the treatment of OLP still remains largely symptomatic because many as yet unknown factors, active in the disease process, still remain to be elucidated.

Effect of IFN-gamma on the expression of MHC class I and class II antigens in a human malignant oral epithelial cell line

This study examined the expression of major histocompatibility complex (MHC) antigens in the KB human carcinoma cell line. MHC class I antigens (HLA-ABC and beta 2microglobulin) were constitutively expressed but not significantly enhanced by interferon-gamma (IFN-gamma). By contrast, MHC class II antigens were absent or expressed minimally on unstimulated KB cells, but DR and DP were significantly stimulated in a non-coordinated pattern (HLA-DR greater than -DP greater than -DQ) by IFN-gamma.

A variant of calcifying epithelial odontogenic tumor with Langerhans cells

A variant of calcifying epithelial odontogenic tumor (CEOT) with Langerhans cells is reported. Compared to a typical CEOT, the tumor islands of this case were thin and composed of a small number of polyhedral epithelial cells. Almost no calcification of homogeneous eosinophilic materials was observed. In addition, clear cells which structurally corresponded to Langerhans cell were intermingled in the epithelial islands. These cells stain positively for S-100 protein, lysozome, MT 1, LN-3 and OKT 6 antibodies, but not for keratin antibody. Electronmicroscopic examination revealed the rod-shaped and racket-shaped structures called Birbeck's granules in the cytoplasm of these clear cells. Our observations indicate a variant case of CEOT with Langerhans cells in tumor nests.

Immunohistologic analysis of epithelial cell populations in oral lichen planus

Previous studies have demonstrated heterogeneity within lesional lymphocytes in drug-related oral lichen planus (D-LP) and idiopathic lichen planus (I-LP). This study examined the phenotype of Langerhans cells (LC) and keratinocytes in non-erosive D-LP and I-LP. In I-LP, keratinocytes expressed HLA-DR antigens whilst LC co-expressed CDIa, MHC Class II and CD4 antigens. The high levels of expression of MHC Class II antigens by LC were maintained during short term organ culture. In I-LP, the epithelium contained occasional CD25+ dendritic cells (putative activated LC). These cell phenotypes are suggestive of cell activation and likely result from local production of gamma interferon. In D-LP, expression of MHC Class II antigens on LC was reduced and no CD25+ cells were detected. The epithelium contained an increased number of CD45RA+ dendritic cells. While no differences between the production of interleukin-1 and interleukin-1 inhibitors by tissue samples could be detected, it is likely that the variations in epithelial cell phenotypes in I-LP and D-LP reflect altered cytokine production.

The activation of Langerhans cells in oral lichen planus

The numbers of CD1, HLADR, HLADP and HLADQ positive, intraepithelial, dendritic cells were compared in lesions of oral lichen planus and normal oral mucosa using an immunoalkaline phosphatase technique. In normal mucosa, there were equal numbers of CD1 and HLADR positive cells but significantly fewer cells were positive for HLADP (P less than 0.001) and HLADQ (P less than 0.05). In lichen planus, the cells appeared more dendritic and equal numbers of CD1, HLADR, HLADP and HLADQ positive cells were found, with significantly more HLADP (P less than 0.01) and HLADQ (P less than 0.05) positive cells than in normal mucosa. There was no change in the number of CD1 and HLADR positive cells. These results show that although there is no change in the total number of Langerhans cells (CD1 positive cells) in lichen planus, there is an increase in Class II major histocompatibility antigen expression. This suggests that in lichen planus, Langerhans cells are immunologically active and play a role in lesion development.