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 in oral epithelium of chronically inflamed human gingivae

This study describes the histopathological features and the distribution of oral epithelial Langerhans cells in 19 gingival biopsies originating from an adult Tanzanian population characterized by very poor oral hygiene and severe gingival inflammation. Light-microscopically, all biopsies contained often large inflammatory connective tissue infiltrates, 6 of which predominantly contained plasma cells while the rest were dominated by lymphocytes. Seven specimens contained peculiar accumulations of round lymphoid and dendritic cells in the lower cell layers of the oral epithelium. These phenomena have not previously been demonstrated in human gingiva and deserve further attention in studies on the pathogenesis of periodontal diseases. Immuno-histochemical staining with OKT6, OKT4 and OKT8 antibodies showed markedly increased numbers of OKT6-positive cells in 7 specimens and clusters of OKT4- and OKT8-positive cells in the oral epithelium of 4 specimens. High numbers of OKT6-positive cells were not related to the presence of intra-epithelial, non-keratinocyte infiltrates or large connective tissue infiltrates. The variable numbers of oral epithelial Langerhans cells may therefore result from different bacterial antigens elucidating different responses or, alternatively, reflect different responses to similar plaque antigens penetrating the surface of the oral epithelium.     

Extent and diversity of inflammatory cell infiltrates in squamous cell carcinomas and basal cell epitheliomas of the head and neck

Using monoclonal antibodies reactive with Langerhans' cells (LCs), macrophages, and T cell subpopulations, the density and proportions of cells of the immune system of the normal oral mucosa were determined immunohistochemically, and compared with findings in oral squamous cell carcinomas (SCC) and basal cell epitheliomas (BCE). In normal oral epithelia, the dominant cell type was the LC, positive for CD 1, and expressing HLA-DR antigens (DR⁺). Many intraepithelial cells were lymphocytes of the suppressor/cytotoxic phenotype (CD 8⁺), which was also the most prominent cell type in the normal mueosal slroma. Significant differences were observed for the content of CD 8-, OKM 1-, and CD 4-positive cells in the epithelium of normal oral mucosa, SCC, and BCE, and for the amount of CD 1-positive Langerhans cells in the connective tissue of the different groups of tissues. When CD 4/CD 8 ratios were calculated, differences between SCC and BCE became most evident. A CD 4/CD 8 ratio greater 0.5 was seen to be characteristic for BCE. Thus, in contrast to the striking preponderance of suppressor/cytotoxic lymphocytes (CD 8⁺) in SCC, BCE showed typically almost balanced numbers of suppressor/cytotoxic (CD 8⁺) and helper/induced (CD 4⁺) lymphocytes. This finding further underlines the biological differences recognized between these most common neoplasias of the head and neck.     

An immunohistochemical study of oral submucous fibrosis

Oral submucous fibrosis (OSF) is a chronic disease of the oral cavity characterized by inflammation and progressive mucosal fibrosis. These reactions may be the result of either direct stimulation from exogenous antigens like areca alkaloids or by changes in tissue antigenicity that may lead to an autoimmune response. This study investigated the presence and distribution of inflammatory cells and MHC class II antigen expression by epithelial and immunocompetent cells using a three-stage immunoperoxidase method on frozen sections. Thirty OSF tissue specimens and ten normal buccal mucosae were studied and compared. All tissues were investigated using antibodies to T cells (CD3), T helper/inducer cells (CD4), T suppressor/cytotoxic cells (CD8), B cells (CD20), naive T cells and monocytes (CD45RA), macrophages. Langerhans' cells (CD68) and HLA-DR-positive cells (HLA-DR alpha). The predominant cell populations detected in normal tissues were CD3, CD4 and HLA-DR-positive cells. The distribution of CD4-positive cells was similar to that of CD3-positive cells, which were scattered, often uniformly distributed, both in the epithelium and connective tissue. CD8-positive cells were occasionally seen in the normal epithelium and lamina propria. Few scattered B cells (CD20) and macrophages (CD681) were observed in normal mucosa. Naive T cells (CD45RA) were seen in all normal tissues focally concentrated around the connective tissue papillae with a similar distribution to that of CD3-positive cells. All normal sections showed HLA-DR-positive cells scattered both in the epithelium and in the lamina propria. Epithelial cells did not show any positive reaction to this antibody and many intraepithelial positive cells showed a dendritic morphology. The cell populations detected in OSF showed higher numbers of CD3 and HLA-DR-positive cells compared with those of the normal tissues. The pattern of staining for CD4-positive cells in OSF tissues was similar to that of CD3-positive cells both in the epithelium and connective tissue and was higher than that in normal tissues. A few scattered CD8-positive cells and only occasional CD20- and CD68-positive cells were seen in OSF sections. Few CD45RA-positive cells were found in the epithelium and lamina propria of OSF sections. However, OSF specimens showed high numbers of HLA-DR-positive cells in the basal layer of the epithelium, juxtaepithelium and in the lamina propria in a similar distribution to that of CD3 cells compared with the normal tissues. Most HLA-DR-positive cells in the epithelium showed dendrites directed vertically towards the surface. The increased evidence of CD4 and HLA-DR-positive cells in OSF tissues suggests that most lymphocytes were activated and shows an increased presence of Langerhans' cells. The presence of these immunocompetent cells and high ratio of CD4 to CD8 in OSF tissues suggest an ongoing cellular immune response leading to a possible imbalance of immunoregulation and alteration in local tissue architecture.     

Oral mucosal Langerhans cells express DR and DQ antigens

The expression of the Class II antigens HLA-DR and HLA-DQ in human oral mucosa was examined in health and in the presence of inflammation. DQ antigens were detected on dendritic intra-epithelial cells which expressed the Langerhans cells (LC) phenotype T6+, DR+. In healthy gingiva, DR and DQ were co-expressed on Langerhans cells, whereas in an experimental gingivitis (day 8), more LC expressed DR than DQ. Absolute LC numbers were increased in inflammation. Traumatic ulceration of the buccal mucosa resulted in a decrease in the density of T6-, DR-, and DQ-positive cells. Repopulation of migrating and regenerated epithelium was complete 10 days after ulcer induction. Disparity between DR and DQ expression was seen in both normal buccal mucosa and throughout the ulcer healing period. These results are in agreement with the reported sequence of Class II antigen expression on lymphoid cells.     

Extent and diversity of inflammatory cell infiltrates in squamous cell carcinomas and basal cell epitheliomas of the head and neck

Using monoclonal antibodies reactive with Langerhans' cells (LCs), macrophages, and T cell subpopulations, the density and proportions of cells of the immune system of the normal oral mucosa were determined immunohistochemically, and compared with findings in oral squamous cell carcinomas (SCC) and basal cell epitheliomas (BCE). In normal oral epithelia, the dominant cell type was the LC, positive for CD 1, and expressing HLA-DR antigens (DR+). Many intraepithelial cells were lymphocytes of the suppressor/cytotoxic phenotype (CD 8+), which was also the most prominent cell type in the normal mucosal stroma. Significant differences were observed for the content of CD 8-, OKM 1-, and CD 4-positive cells in the epithelium of normal oral mucosa, SCC, and BCE, and for the amount of CD 1-positive Langerhans cells in the connective tissue of the different groups of tissues. When CD 4/CD 8 ratios were calculated, differences between SCC and BCE became most evident. A CD 4/CD 8 ratio greater 0.5 was seen to be characteristic for BCE. Thus, in contrast to the striking preponderance of suppressor/cytotoxic lymphocytes (CD 8+) in SCC, BCE showed typically almost balanced numbers of suppressor/cytotoxic (CD 8+) and helper/inducer (CD 4+) lymphocytes. This finding further underlines the biological differences recognized between these most common neoplasias of the head and neck.     

In situ characterization of mononuclear cells in human chronic marginal periodontitis using monoclonal antibodies

Acetone fixed cryostat sections from 25 patients with adult chronic marginal periodontitis were characterized using an indirect immunofluorescence technique with monoclonal antibodies. The amount of B lymphocytes (Leu-12 positive) varied considerably between the specimens and were usually seen in largest numbers in the most apical parts of the cellular infiltrates beneath the pocket epithelium (PE). Varying amounts of T lymphocytes (OKT 3 positive) were demonstrated in all specimens. The amount of T helper cells (OKT 4a positive) exceeded that of T suppressor/cytotoxic cells (OKT 8 positive) in the cellular infiltrates beneath the PE (OKT 4a/ OKT 8 =1.13). There was a more even distribution of these cell types beneath the oral gingival epithelium (OGE). Langerhans cells were observed within and occasionally subjacent to the OGE. Scattered macrophages (Leu-M3 or OK Ia 1 positive) were observed in the inflammatory cell infiltrates and on the connective tissue papillae beneath the OGE. HLA-DR antigen reacting with OK Ia 1 was present on cells corresponding to OKT 6 positive cells in the OGE and subjacent to the OGE as well as in the inflammatory cell infiltrates beneath the PE and in the perivascular infiltrates. In some specimens HLA-DR antigen was also found to be associated with keratinocytes in the outer parts of the OGE. Occasional NK cells (Leu-7 positive) were localized inside and subjacent to the OGE. There was a considerable variation with respect to the number and distribution of the various mononuclear cells between specimens and from section to section from the same specimen.     

Langerin-expressing and CD83-expressing cells in oral lichen planus lesions

OBJECTIVE: Dendritic Langerhans cells (LCs) have been attributed a role in the pathogenesis of lichen planus as autoantigen-presenting cells initiating expansion of autoreactive T cells. Langerin and CD83, which are cell molecules expressed on LCs, are associated with antigen presentation. The present study examined expression of Langerin and CD83 molecules on LCs in patients with oral lichen planus (OLP). MATERIAL AND METHODS: Biopsies were obtained from seven patients with OLP. Oral mucosa from seven healthy subjects served as controls. Monoclonal antibodies (mAbs) were used in standard immunohistochemical procedures to visualize CD1a-, Langerin-, and CD83-molecule-expressing cells. RESULTS: CD1a+ and Langerin+ cells were found in significantly higher frequencies in OLP epithelium compared with healthy oral epithelium (p<0.01 and p<0.05, respectively); however, the frequency of CD83+ cells did not differ (p>0.05). The connective tissue in OLP lesions showed significantly higher frequencies of CD1a+, Langerin+, and CD83+ cells compared with healthy connective tissue (p<0.01, p<0.01, and p<0.05). CD1a+ and Langerin+ cells in OLP and healthy epithelium had a dendritic morphology. CONCLUSIONS: The study shows increased numbers of CD1a- and Langerin-expressing LCs in OLP compared with healthy controls. In the connective tissue, CD83+ cells with dendritic morphology were localized to regions of lymphocyte clusters. The presence of CD83+ dendritic cells in areas of lymphocyte clusters in the connective tissue of OLP lesions indicates the possibility of ongoing autoantigen presentation.     

Quantitative analysis of immunocompetent cells in human normal oral and uterine cervical mucosa, oral papillomas and leukoplakias

Using monoclonal antibodies reacting with T-cell subpopulations, Langerhans cells and macrophages, the number and distribution of cells of the immune system in normal oral and cervical mucosa was determined and statistically compared with that in oral papillomas and oral leukoplakias. Increased numbers of labelled cells were found in oral leukoplakias and particularly in oral papillomas. In the epithelium of all specimens, Langerhans cells and T-lymphocytes of the suppressor/cytotoxic phenotype as well as of the helper phenotype were seen. Suppressor/cytotoxic and helper T-lymphocytes were in equal numbers in the epithelium of oral papillomas, but were about 2:1 in all other lesions. In normal oral epithelium, macrophages were rare but were in greater numbers in leukoplakias and papillomas. In the connective tissue of all lesions, more labelled cells were present than in epithelium with T-lymphocytes predominant. Although Langerhans cells were rare in connective tissue, many were seen in oral papillomas.     

Reduced numbers of Langerhans cells and increased HLA-DR expression in keratinocytes in the oral gingival epithelium of HIV-infected patients with periodontitis

BACKGROUND: HIV-seropositive (HIV+) patients become increasingly susceptible to periodontal diseases as HIV infection proceeds. We have previously shown that HIV+ patients with chronic marginal periodontitis (CMP) have remarkably increased numbers of gingival plasma cells in the connective tissue underlying the oral gingival epithelium, but depressed specific serum IgG levels towards periodontopathogenic bacteria. Langerhans cells (LC) and keratinocytes (KC) are antigen-presenting cells that are important in promoting immune responses. METHOD: In this study we examined, by means of immunofluorescence, the distribution and numbers of LC and activated KC in biopsies taken from inflamed periodontal sites in HIV+ and HIV patients with CMP. RESULTS: In the pocket epithelium in both patient groups, basal layer KC expressed HLA-DR molecules. In the oral gingival epithelium of HIV+ patients, basal layer KC also expressed HLA-DR molecules and numbers of LC were decreased as compared with HIV persons. CONCLUSION: The findings suggest that the oral gingiva in HIV+ patients may be affected by inflammation.     

Identification of inflammatory cell phenotypes in human oral carcinomas by means of monoclonal antibodies

Monoclonal antibodies reacting with human T cell sub-populations, Langerhans cells and macrophages were used to examine the quantitative distribution of immune-competent cells in normal oral mucosa and invasive oral carcinomas. Both immunofluorescent and immunoperoxidase procedures were applied. In normal oral epithelia, the dominant immune-reactive cell was the Langerhans cell, positive for OKT 6 and expressing HLA-DR gene products (OKIal⁺). Many intra-epithelial non-epithelial cells (non-keratinocytes), belonged to the lymphocyte system carrying the suppressor/cytotoxic phenotype (OKT 8⁺). This lymphocyte sub-population was also the most prominent cell type in the normal mucosal stroma. The quantitative evaluation of immune-competent cells in squamous cell carcinomas revealed elevated numbers of all the inflammatory cell sub-populations investigated (suppressor/cytotoxic lymphocytes, helper/inducer lymphocytes, Langerhans cells, macrophages) compared with the normal oral mucosa. There was a striking increase in suppressor/cytotoxic lymphocytes (OKT 8⁺) and in cells of the macrophage system, including Langerhans cells (OKIal⁺, OKM l⁺, OKT 6⁺). In the stroma distant to the tumour complexes, many helper/inducer lymphocytes (OKT 4⁺) were also observed.     

Do Langerhans cells behave similarly in elderly and younger patients with chronic periodontitis?

OBJECTIVE: The purpose of this study was to compare the number, the distribution and the expression of markers of maturation of Langerhans cells (LC) in elderly and younger patients with chronic periodontitis in order to evidence the effect of aging on LC in inflammatory gingival tissue. METHODS: Gingival tissue specimens presenting chronic periodontitis from 8 elderly patients aged >75 (group E) and from 8 younger patients aged 50-60 (considered as controls, group C) were used for immunohistochemistry with monoclonal antibodies against CD45RB (leucocytes), CD1a (LC), markers of LC maturation (DC-LAMP, CD83) and number of immunolabelled cell subsets was evaluated using image analysis. RESULTS: The difference in the number of CD45RB+ leucocytes in the upper connective tissue between groups was not significant. In group E, the number of CD1a+ LC was significantly decreased (P<0.002) in the epithelium and significantly increased (P<0.0004) in the upper connective tissue. Furthermore, in group E, intraepithelial CD1a+ LC are more often observed in the upper epithelium and their dendritic processes were shorter and less numerous. Concerning the expression of markers of maturation, the numbers of intraepithelial DC-LAMP+ cells and CD83+ cells were significantly increased (P<0.0007 and P<0.02, respectively) in group E. CONCLUSION: During chronic periodontitis in elderly patients, the decrease in the number of intraepithelial LC and the alteration of dendritic processes could be balanced by a cellular distribution often observed in the upper epithelium associated with changes in cell maturation in response to bacterial elements.     

Quantification and distribution of lymphocyte subsets and Langerhans cells in normal human oral mucosa and skin

Normal human oral (check) mucosa was studied to discover whether the oral cavity resembles the Mucosal Immune System (MIS) or the Skin Immune System (SIS). Immunophenotypes of lymphocyte subsets and Langerhans cells (LC) with their exact locations in the epithelium and papillary layer of the normal buccal mucosa were determined and compared with data of normal human skin. In a double staining procedure, the distribution of T-lymphocytes in relation to blood and lymph vessels was determined. Immunophenotyping of LC was done with a CD1a monoclonal antibody. In contrast to the skin, T-lymphocytes in buccal mucosa are not primarily perivascular in location. They are more or less randomly distributed on both sides of the basement membrane. The epithelium of the buccal mucosa contains about 37 times as many T-lymphocytes as the epidermis of normal skin. T-cell numbers in the papillary layer are more or less comparable. The CD4/CD8 ratios of about 1/2 in the epithelium of buccal mucosa and 1/4 in the skin indicates preferential presence of the CD8 subset in both sites, but the helper/inducer T-lymphocytes play a much greater role in the epithelium of the buccal mucosa when compared with skin. B-lymphocytes were not found in the epithelium and papillary layer of the buccal mucosa. Thus, immune response associated cells in buccal mucosa do not show the MIS pattern since B cells are absent. It has more in common with SIS but differences are also apparent. In the epithelium of the buccal mucosa the density of LC does not differ significantly from that of the skin, but the papillary layer of the buccal mucosa contains significantly fewer LC than the skin. As in the skin most of the LC of the buccal mucosa are found in the epithelium.     

Langerin-expressing and CD83-expressing cells in oral lichen planus lesions

Objective. Dendritic Langerhans cells (LCs) have been attributed a role in the pathogenesis of lichen planus as autoantigen-presenting cells initiating expansion of autoreactive T cells. Langerin and CD83, which are cell molecules expressed on LCs, are associated with antigen presentation. The present study examined expression of Langerin and CD83 molecules on LCs in patients with oral lichen planus (OLP). Material and methods. Biopsies were obtained from seven patients with OLP. Oral mucosa from seven healthy subjects served as controls. Monoclonal antibodies (mAbs) were used in standard immunohistochemical procedures to visualize CD1a-, Langerin-, and CD83-molecule-expressing cells. Results. CD1a+ and Langerin+ cells were found in significantly higher frequencies in OLP epithelium compared with healthy oral epithelium (p<0.01 and p<0.05, respectively); however, the frequency of CD83+ cells did not differ (p>0.05). The connective tissue in OLP lesions showed significantly higher frequencies of CD1a+, Langerin+, and CD83+ cells compared with healthy connective tissue (p<0.01, p<0.01, and p<0.05). CD1a+ and Langerin+ cells in OLP and healthy epithelium had a dendritic morphology. Conclusions. The study shows increased numbers of CD1a- and Langerin-expressing LCs in OLP compared with healthy controls. In the connective tissue, CD83+ cells with dendritic morphology were localized to regions of lymphocyte clusters. The presence of CD83+ dendritic cells in areas of lymphocyte clusters in the connective tissue of OLP lesions indicates the possibility of ongoing autoantigen presentation.     

Human gingival Langerhans cells in health and disease

Epithelial Langerhans cells in samples of healthy and diseased gingival tissue were studied using ATPase histochemistry and the monoclonal antibodies OKT6 and anti HLA-DR. In healthy gingiva Langerhans cells were seen in both oral and sulcular epithelium; they were generally positioned in the basal layers. No Langerhans cells were seen in junctional epithelium. In diseased tissue there was a large increase in the number of Langerhans cells in both oral and sulcular epithelium with many more being situated in the stratum spinosum. There was an increase in the expression of the Class 2 antigen, HLA-DR, and morphological polarization occurred with dendrites preferentially orientated towards the surface. No Langerhans cells were seen in the pocket lining epithelium of periodontally diseased gingiva.     

Intra-epithelial subpopulations of T lymphocytes and Langerhans cells in oral lichen planus

This study has addressed the question of whether there is selective recruitment and distribution of intra-epithelial leucocytes in lesions of oral lichen planus (OLP). T-lymphocyte subsets were examined in the epithelium and peripheral blood of patients and controls using flow cytometry and double immunofluorescence, and the relationship between keratinocyte intercellular adhesion molecule-1 (ICAM-1) expression with T-lymphocyte and Langerhans cell (LC) distribution was examined. The circulating 'memory'subset (CD45RO⁺) of T-helper cells (CD4⁺) was increased from 49.1% in controls to 65.7% in patients ( P = 0.005), while the 'naive'subset (CD45RA⁺), which was absent from control epithelium, comprised 24% of helper cells in OLP ( P =0.037) and all T-cell and LC counts were significantly raised in ICAM-1-expressing areas of epithelium. These data demonstrate changes in intra-epithelial T-lymphocyte and LC populations compared with normal oral mucosa and suggest there is selective recruitment in OLP. In addition, Keratinocyte ICAM-1 expression does appear to be associated with accumulation of infiltrating T lymphocytes and LC.     

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

Numbers of Langerhans ceils (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 intra-epithelia! 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.     

Macrophages, dendritic cells and T lymphocytes in rat buccal mucosa and dental pulp following 5-fluorouracil treatment

Cancer chemotherapeutic drugs may affect immunocompetent cells of oral soft tissues, causing an impaired capacity to induce immune defence reactions. This study was designed to investigate changes in the number of macrophages, dendritic cells and T lymphocytes in the oral mucosa and dental pulp following treatment with the antineoplastic agent 5-fluorouracil (5-FU). Rats were given 5-FU (30 mg/kg or 50 mg/kg) i.v. on days 0, 1, 2, 5, 6 and 7. The number of cells in buccal epithelium and dental pulp expressing ED2, MHC class II, or CD2 molecules was analyzed following immunohistochemical peroxidase staining. Major histocompatibility complex (MHC) class II molecules were analyzed in epithelial sheets and in epithelial cell suspensions by flow cytometry. Increasing concentrations of 5-FU changed the morphology of the epithelial Langerhans cells with a reduced dendritic appearance as the most prominent feature. At 50 mg/kg of 5-FU, the oral epithelium detached from the connective tissue at the basement membrane. MHC class II molecule-expressing cells were reduced in number in the lamina propria of the buccal mucosa and in the dental pulp after both low and high dose of 5-FU, but only after high dose in the epithelium. The number of ED2- and CD2-expressing cells in the dental pulp was only slightly reduced by 5-FU treatment at both low and high dose, while these cells decreased in number in the oral mucosa. The varying sensitivity to 5-FU by macrophages, dendritic cells, and T cells depending on the tissues in which they reside may be due to differences in cell origin or differences in antigenic load.     

Langerhans cells in candidal leukoplakia

Using histochemical and immunohistochemical methods, we examined specimens of Candidal leukoplakia from the oral mucosa of 5 smokers to determine the morphological relationships between Candida and Langerhans cells (LC) in tissue sections. LC were fairly evenly distributed in control sections, but had a patchy distribution in lesions. Fewer LC were found in lesions than in control tissue, but the difference was not statistically significant. Candidal antigens were not detected on LC by the methods used, but we found ATPase-positive LC among, or at least near, intraepithelial candidal hyphae. However, sections double-reacted with anti- Candida and T6 antibodies to label candidal antigens and LC. respectively, showed a clear zone of epithelium between the T6-positivc LC and the candidal hyphae. The difference in distribution of ATPase-positive and T6-positive LC may indicate locations of 2 subtypes of LC, or a change in T6 antigen expression by the LC closest to the candidal hyphae.     

Langerhans cells in candidal leukoplakia

Using histochemical and immunohistochemical methods, we examined specimens of candidal leukoplakia from the oral mucosa of 5 smokers to determine the morphological relationships between Candida and Langerhans cells (LC) in tissue sections. LC were fairly evenly distributed in control sections, but had a patchy distribution in lesions. Fewer LC were found in lesions than in control tissue, but the difference was not statistically significant. Candidal antigens were not detected on LC by the methods used, but we found ATPase-positive LC among, or at least near, intraepithelial candidal hyphae. However, sections double-reacted with anti-Candida and T6 antibodies to label candidal antigens and LC, respectively, showed a clear zone of epithelium between the T6-positive LC and the candidal hyphae. The difference in distribution of ATPase-positive and T6-positive LC may indicate locations of 2 subtypes of LC, or a change in T6 antigen expression by the LC closest to the candidal hyphae.