Expression of Class II transplantation antigens by epithelial cells in oral candidosis, oral lichen planus and gingivitis

Microbial interactions and immunity response in oral Candida species

Oral candidiasis are among the most common noncommunicable diseases, related with serious local and systemic illnesses. Although these infections can occur in all kinds of patients, they are more recurrent in immunosuppressed ones such as patients with HIV, hepatitis, cancer or under long antimicrobial treatments. Candida albicans continues to be the most frequently identified Candida spp. in these disorders, but other non-C. albicans Candida are rising. Understanding the immune responses involved in oral Candida spp. infections is a key feature to a successful treatment and to the design of novel therapies. In this review, we performed a literature search in PubMed and WoS, in order to examine and analyze common oral Candida spp.-bacteria/Candida-Candida interactions and the host immunity response in oral candidiasis.

Geographic tongue: assessment of peripheral nerve status, Langerhans cell, and HLA-DR expression

OBJECTIVES

The objectives of this study were to determine whether geographic tongue (GT) is an antigen-driven condition by assessing Langerhans cell numbers and the expression of human leukocyte antigen (HLA)-DP, -DQ, and -DR in the epithelium of GT and to assess peripheral nerve status for any possible damage/injury association by quantifying neurite area in connective tissue in GT.

STUDY DESIGN

Randomly selected samples of GT were examined by using routine immunoperoxidase staining methods to S100 protein, neurofilament, CD1a, and HLA class II. The Student t test and Mann-Whitney U test were used to assess statistical significance.

RESULTS

Langerhans cell numbers were found to be increased in GT. HLA expression was also seen in Langerhans cells and inflammatory cells and in the spinous layer and parabasal epithelial cells in 2 samples of GT. Total nerve tissue, based on area measurements, was not significantly different between GT and control tissues.

CONCLUSIONS

The increase in Langerhans cells suggests that GT is a condition that is likely driven by an unknown external antigen. Peripheral nerve damage was not apparent, suggesting that this is not a mechanism whereby patients with GT become symptomatic.

Immunology of oral candidiasis

A successful pathogen is one that is able to effectively survive and evade detection by the host immune defense. Oral candidiasis has adopted strategies, which evade host defense and eventually cause disease in at-risk patients. Host defense against infections with Candida spp. depends on rapid activation of an acute inflammatory response by innate immunity, followed by an incremental stimulation of specific immune responses mediated by T-cells (cellular immunity) or B-cells (humoral immunity). Understanding these complex pathways of immune evasion can potentially contribute to the development of novel therapeutic strategies against oral candidiasis.

In silico prediction and immunological validation of common HLA-DRB1-restricted T cell epitopes of Candida albicans secretory aspartyl proteinase 2

ABSTRACT Sap2 is the most abundant virulence factor expressed during Candida infection, and the principal protein known to induce antibody response during Candida infection in humans. Its role in T-cell activation however, has not yet been determined. Sequence analysis revealed that Sap2 contains two variable regions: Var1 and Var2. Computational predictions by the Hotspot Hunter program identified that Var1 contains three candidate T-cell epitopes, whereas Var2 contains four. Thirty-nine overlapping peptides of Sap2 were then synthesized, and tested for their ability to induce proliferation of PBMC from 12 donors. Peptides P11, P17 and P31 exhibited significantly higher proliferative indices when compared with those of other peptides or controls. P17 and P31 are located in the areas of prediction, while P11 is not. There were other peptides outside the prediction areas that could stimulate PBMC proliferation at low levels. Nevertheless, the proliferative noise caused by such peptides was ruled out by IL-2 ELISpot analysis. Only P17 and P31 were shown to induce clonal proliferation of IFN-gamma producing lymphocytes, suggesting that these two peptides contain T cell epitopes. P11, which stimulated IL-2 producing clones, contains a known B-cell epitope. Interestingly, P17 and P31 elicited both Th1 and Th2 cell responses with significant numbers of IL-13 secreting clones in response to stimulation. Taken together, the computer-based T cell epitope prediction method could identify the immunogenic T cell epitopes of C. albicans Sap2 that promiscuously bind to the HLA-DRB1 supertype.

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.

Immunopathogenesis of oropharyngeal candidiasis in human immunodeficiency virus infection

Oropharyngeal and esophageal candidiases remain significant causes of morbidity in human immunodeficiency virus (HIV)-infected patients, despite the dramatic ability of antiretroviral therapy to reconstitute immunity. Notable advances have been achieved in understanding, at the molecular level, the relationships between the progression of HIV infection, the acquisition, maintenance, and clonality of oral candidal populations, and the emergence of antifungal resistance. However, the critical immunological defects which are responsible for the onset and maintenance of mucosal candidiasis in patients with HIV infection have not been elucidated. The devastating impact of HIV infection on mucosal Langerhans' cell and CD4(+) cell populations is most probably central to the pathogenesis of mucosal candidiasis in HIV-infected patients. However, these defects may be partly compensated by preserved host defense mechanisms (calprotectin, keratinocytes, CD8(+) T cells, and phagocytes) which, individually or together, may limit Candida albicans proliferation to the superficial mucosa. The availability of CD4C/HIV transgenic mice expressing HIV-1 in immune cells has provided the opportunity to devise a novel model of mucosal candidiasis that closely mimics the clinical and pathological features of candidal infection in human HIV infection. These transgenic mice allow, for the first time, a precise cause-and-effect analysis of the immunopathogenesis of mucosal candidiasis in HIV infection under controlled conditions in a small laboratory animal.

Oral lichen planus part I: epidemiology, clinics, etiology, immunopathogeny, and diagnosis

This article presents a review of the literature on oral lichen planus, focusing on important aspects of its epidemiology, etiopathogeny, and clinical manifestations. The oral form is an important clinical presentation of lichen planus. It may precede or accompany the skin lesions, or it may be the only manifestation of the disease. Dermatologists, dentists, otorhinolaryngologists, and other specialists who deal with the oral cavity must be aware of this disease so they can diagnose, treat, and keep these patients under observation.

Langerhans cells and T cells in oral graft versus host disease and oral lichen planus

Chronic graft versus host disease (cGVHD) of the oral mucosa, following allogeneic stem cell transplantation, and oral lichen planus (OLP) are both mucosal diseases where the immune system is involved in the pathogenesis. Although the aetiology of the two conditions is different, they present with a similar clinical appearance. This study compares the two diseases regarding the distribution of cells, which are expressing cell surface markers of interest for inflammatory responses. Monoclonal antibodies (MoAbs) were used in standard immunohistochemical procedures. CD1a+, CD80+ and CD86+ cells in the epithelium of OLP- and cGVHD lesions had the dendritic morphology of Langerhans cells (LC). Higher frequencies of CD1a+ LC as well as CD25+ cells were observed in the OLP epithelium than in the cGVHD epithelium. The OLP lesions showed higher frequencies of subepithelial cells expressing CD1a, CD86, CD4, CD8 and CD25 than the cGVHD lesions. Notably there was a significantly higher frequency of CD25+ cells in the epithelium and the connective tissue of OLP than in cGVHD. These cells might represent regulatory T cells. In conclusion, cGVHD and OLP show marked differences at the cellular level despite similar clinical appearance. Hence, the findings indicate differences in the regulation of the inflammatory response between the two conditions.

Distribution of interferon-gamma mRNA-positive cells in oral lichen planus lesions

The present study investigated the potential involvement of interferon-gamma (IFN-gamma)-producing cells in the pathogenesis of oral lichen planus (OLP). On biopsies from 10 OLP patients, an in situ hybridization technique was employed to determine the topographical distribution of cells expressing IFN-gamma mRNA. It was estimated that approximately 1% or fewer lesional cells were IFN-gamma mRNA-positive. These cells were mainly encountered lining the basal membrane in a majority of the patients, or were in a few cases circumscribing the infiltrate, but were more seldom localized to the center of the lesion. A slightly higher, but not statistically significant, number of phytohemagglutinin (PHA)-induced IFN-gamma-producing cells, in vitro, was found in blood from 11 other OLP patients compared with blood from matched controls. Equal concentrations of IFN-gamma in supernatants from PHA-stimulated blood cells were detected in the two groups. Similarly, the IFN-gamma response towards C. albicans was alike in OLP and in healthy control (HC) blood cells, indicating normal immunological memory function in the OLP patients. A small set of cells with spontaneous IFN-gamma production was found in OLP and in HC peripheral blood. The data suggest that T-lymphocyte activation and cytokine production act locally and are not reflected in peripheral blood. The localization of the IFN-gamma mRNA-positive cells indicates that the antigenic peptides are presented at the periphery of the mononuclear cell infiltrate. Furthermore, the low frequency of IFN-gamma mRNA-positive cells in the lesions suggests that the disease is maintained by a small number of antigen-specific T cells.

Characterisation of the inflammatory cell infiltrate in chronic hyperplastic candidosis of the oral mucosa

The inflammatory cell infiltrate in biopsy material of chronic hyperplastic candidosis (CHC) from the oral mucosa was characterised using immunocytochemical techniques. Nine specimens were stained for human kappa and lambda immunoglobulin light chains, CD68 antigen (macrophages), lysozyme (macrophages, granulocytes), CD3 antigen (T-lymphocytes), CD20 antigen (B-lymphocytes) and leucocyte common antigen (LCA). In addition, these and a further 13 specimens were also examined for immunoglobulin (Ig)-containing cells (IgA, IgG and IgM). The density of the infiltrate varied considerably between cases; T-lymphocytes were the dominant cell type (53.9%), with fewer B-lymphocytes (8.2%) and macrophages (14.2%). Many Ig-containing cells were seen, and although IgG-containing cells predominated, (60.8%, SD +/- 9.0) there was a high proportion of IgA-containing cells (36.7%, SD +/- 9.1) with few IgM-containing cells (2.5%, SD +/- 3.0). Many neutrophils, together with smaller numbers of T-lymphocytes and macrophages, were seen in the epithelium. It is suggested that mucosal defence to Candida infection involves a cell-mediated reaction in which there is recruitment of macrophages and local production of immunoglobulin with a prominent IgA component.

T cell antigen receptor expression by intra-epithelial lymphocytes in oral lichen planus

The distribution of T lymphocytes expressing the alpha beta or gamma delta heterodimer of the T cell receptor (TCR) was examined in normal oral mucosa (NOM) and reticular oral lichen planus (OLP) using a panel of antibodies specific for CD3, the alpha beta TCR and the gamma delta TCR. Intra-epithelial lymphocytes were counted and epithelial surface length was measured by image analysis. T cells in the lamina propria were not quantified. Total intra-epithelial lymphocytes were increased in OLP compared with NOM (P = 0.0004). The proportions of cells expressing the gamma delta TCR in NOM and OLP were 10% and 9.3%, respectively, suggesting there is no selective recruitment from the circulation of either alpha beta or gamma delta TCR-bearing cells into normal oral epithelium or that affected by OLP. The role, if any, of gamma delta T cells in the pathogenesis of OLP remains to be determined.

Cytokine regulation of major histocompatibility complex antigen expression by human oral and skin keratinocytes

The expression, and cytokine modulation, of major histocompatibility complex (MHC) class I and class II molecules on oral and skin keratinocytes were compared in cell culture. Both cell types expressed class I, but not class II, constitutively. However, stimulation with interferon-gamma, but not interleukin-1 alpha, and -1 beta, tumour necrosis factor-alpha or lymphotoxin, induced increased expression of class I and de-novo expression of HLA-DR on both cell types. Oral keratinocytes differed from skin keratinocytes in that they exhibited greater sensitivity to interferon-gamma stimulation and higher stimulated expression of both class I and HLA-DR. In addition, interferon-gamma stimulated oral, but not skin, keratinocytes to express HLA-DP and -DQ. These observations suggest that, like skin keratinocytes, under certain conditions, oral keratinocytes may be able to act as antigen-presenting cells. This may be important in the initiation and progression of some immune-mediated mucocutaneous diseases. Moreover, differences in MHC expression may help to explain differences in the presentation of these diseases on the skin and oral mucosa.

Production and function of cytokines in natural and acquired immunity to Candida albicans infection

Host resistance against infections caused by the yeast Candida albicans is mediated predominantly by polymorphonuclear leukocytes and macrophages. Antigens of Candida stimulate lymphocyte proliferation and cytokine synthesis, and in both humans and mice, these cytokines enhance the candidacidal functions of the phagocytic cells. In systemic candidiasis in mice, cytokine production has been found to be a function of the CD4+ T helper (Th) cells. The Th1 subset of these cells, characterized by the production of gamma interferon and interleukin-2, is associated with macrophage activation and enhanced resistance against reinfection, whereas the Th2 subset, which produces interleukins-4, -6, and -10, is linked to the development of chronic disease. However, other models have generated divergent data. Mucosal infection generally elicits Th1-type cytokine responses and protection from systemic challenge, and identification of cytokine mRNA present in infected tissues of mice that develop mild or severe lesions does not show pure Th1- or Th2-type responses. Furthermore, antigens of C. albicans, mannan in particular, can induce suppressor cells that modulate both specific and nonspecific cellular and humoral immune responses, and there is an emerging body of evidence that molecular mimicry may affect the efficiency of anti-Candida responses within defined genetic contexts.

Expression of HLA class II antigens in marginal periodontitis of patients with Down's syndrome

The expression of HLA Class II antigens on the surfaces of immunocompetent cells and the presence of CD1a+ cells (Langerhans cells) are important components of antigen presentation. Quantitative variations in HLA class II expression on antigen-presenting cells play a role in immune regulation. An indirect immunofluorescent technique was used on cryostat sections to reveal such differences qualitatively or quantitatively between chronic marginal periodontitis (CMP) in patients with Down's syndrome (DS) and in otherwise normal patients (NP). We found increased frequency of HLA Class II (HLA-expression on inflammatory cells and on keratinocytes of the oral gingival epithelium) in CMP of DS patients compared to sections from NP. The expression of HLA-DR was more frequent on the keratinocytes of the pocket epithelium in NP than in DS. There were significantly higher numbers of CD1a+ cells and ratios of HLA-DR+/CD1a+ cells and HLA-DP+/CD1a+ cells in the DS group compared to the NP group. Our conclusion is that there is a more pronounced inflammatory process in the gingival sites with CMP of DS patients compared to CMP in NP. The findings also indicate that there is a highly activated immune response in CMP of DS patients.

Expression of human intercellular adhesion molecules in middle ear cholesteatoma

INTRODUCTION

Cell adhesion molecules are cell surface proteins that allow specific cell-cell interactions among leukocytes, as well as between leukocytes and other cells. Because middle ear cholesteatoma is characterized by the presence of leukocyte infiltrates, the presence of the two molecule types of intercellular adhesion molecules (ICAM-1 and ICAM-2) was investigated on cholesteatoma using monoclonal antibodies.

METHODS

Tissue sections from 10 patients with cholesteatoma, and normal skin from 5 patients were prepared for alkaline-phosphatase--anti-alkaline-phosphatase (APAAP) staining.

RESULTS

ICAM-1 and ICAM-2 were present in normal skin in microvascular endothelial cells and in intersticial cells of the dermis. Cholesteatoma showed a very important increase of the ICAM-1 expression with comparison to human skin. All infiltrating immune cells showed positive reactions for the antibody. Furthermore, the intensity of the staining of vessels cells was higher than in normal skin. Keratinocytes were only positive if a very heavy infiltrate was present subepidermally. ICAM-2 was present in endothelial and intersticial cells in normal skin and in cholesteatoma. Most of the infiltrating cells in the cholesteatoma stroma showed positive reactions for the anti-ICAM-2 antibody.

CONCLUSION

Our results suggest that both ICAM-1 and ICAM-2 play a central role in the regulation of the inflammatory disorders observed in cholesteatoma.

Candida and oral candidosis: a review

Candida species are the most common fungal pathogens isolated from the oral cavity. Their oral existence both as a commensal and an opportunist pathogen has intrigued clinicians and scientists for many decades, and recent investigations have revealed many attributes of this fungus contributing to its pathogenicity. In addition, the advent of the human immunodeficiency virus infection and AIDS has resulted in a resurgence of oral Candida infections. Clinicians are witnessing not only classic forms of the diseases but also newer clinical variants such as erythematous candidosis, rarely described hithertofore. Therefore, this review is an attempt at detailing the current knowledge on Candida and oral candidoses together with the newer therapeutic regimes employed in treating these mycoses.

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.

Enhancement of MHC class II antigen expression by exposure to Candida albicans

In oral infections with the yeast Candida albicans, the expression of MHC class II antigens on keratinocytes has been reported to be enhanced. In the present experiments, exposure to C. albicans or its products in vitro was found to increase the expression of class II MHC antigens on thioglycollate-induced mouse macrophages, and on LK cells (an antigen-presenting cell line). The implications of this finding for the understanding of immunoregulation and susceptibility to C. albicans infection are discussed.

Immunologically activated cells in aural cholesteatoma

In this immunohistochemical study, we characterized the cells infiltrating the stroma of acquired aural cholesteatomas in detail, using a panel of monoclonal antibodies directed against immune cell type-specific antigens, HLA class II antigens, and interleukin-2 receptor. For all antibodies used, normal ear skin was stained for comparison. The vast majority of the infiltrating cells was CD45-positive, ie, derived from bone marrow. Reactivity with anti-CD3 and anti-CD6 antibodies revealed an abundant infiltration of T lymphocytes beneath the squamous epithelium of cholesteatoma. The B lymphocyte-specific anti-CD19 and anti-CD22 antibodies detected only occasional positive cells. Hence, the cellular infiltrate in the stroma of aural cholesteatoma is made up primarily of T cells with macrophages scattered between them. Expression of HLA-DR was almost as high as that of CD45, whereas CD25-positive cells were detected in lower amounts. We infer that the majority of T cells and macrophages in the stroma of cholesteatoma are in an immunologically activated state. The characteristics of the infiltrating cell population suggest an antigen-driven process in cholesteatoma.

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.

What's new in the mechanisms of host resistance to Candida albicans infection?

Despite extensive investigation, the mechanisms of host resistance against C. albicans infection remain poorly understood. Granulocytes and macrophages are the major effector cell types; however, their intrinsic candidacidal activity is rather limited, and its full expression requires augmentation by components of the T cell-initiated lymphokine cascade. Consequently, susceptibility to recurrent mucocutaneous infections may be associated with aberrant T cell function. In contrast, protection from systemic infection appears to be mediated by candida-specific antibodies.

Murine candidiasis: susceptibility is associated with the induction of T cell-mediated, strain-specific autoreactivity

Inbred mice can be classified as susceptible or resistant to systemic infection with the yeast Candida albicans by histopathological evaluation of tissue lesions. Candida-specific memory T cell responses generated by resistant BALB/c mice are vigorous and sustained, whereas those displayed by susceptible CBA/H mice are weak. When spleen cells from immune mice were activated by culture with candida antigens in vitro, and injected into syngeneic and allogeneic recipients in the absence of further antigenic stimulation, cells from CBA/H mice induced a specific inflammatory response only in CBA/H recipients. In contrast, cells from immune BALB/c mice showed no specific activity. The effector cells were identified as T cells of the cytotoxic/suppressor subclass (CD4-, CD8+); and analysis in various F1 hybrid mice showed that reactivity was expressed only in animals carrying CBA/H genes. The data thus indicate that susceptibility to C. albicans infection is associated with the induction of a T cell subpopulation that has the potential to react specifically against unmodified self antigens expressed by the susceptible strain.

T lymphocytes, Langerhans cells and HLA-DR expression on keratinocytes in oral lesions associated with amalgam restorations

It has been shown recently that patients with mucosal lesions confined to areas opposing amalgam restorations (contact lesions) show a high rate of allergic reaction towards mercury. These lesions may, therefore, represent a contact hypersensitivity reaction. Contact lesions often have a lichenoid appearance. From a pathogenetic and differential diagnostic point of view we therefore evaluated the presence of lymphocyte subpopulations, Langerhans cells (LC) and the expression of HLA-DR antigens on mucosal keratinocytes in biopsies of contact lesions (Group 1) and in lichen planus lesions with (Group 2) and without (Group 3) partial contact with amalgam restorations. T lymphocytes dominated in all three groups and LC counts were similar. HLA-DR positive keratinocytes were found in 18-36% of lesions in all three groups. Thus, the immunologic parameters examined are not of value in discriminating between the types of lesions studied. Rather, it seems that the pattern observed is a common reaction of the oral mucosa to known (amalgam restorations) and unknown factors.

Expression of CDw29 and CD45R antigens on epithelial cells in oral lichen planus

The CD45R and CDw29 antigens are expressed on naive and primed helper T cell populations which serve suppressor-inducer or helper-inducer functions, respectively. These antigens may also be expressed on epithelial cell subpopulations. In the present study, monoclonal antibodies reacting with T lymphocytes and Langerhans cells (LC) were used to characterize the expression of CD45R and CDw29 antigens in oral lichen planus. CDw29 was expressed by LC and lymphocytic cells whereas keratinocyte reactivity varied from negative through to full thickness staining. Expression of CD45R was confined to intraepithelial cells with either lymphocytic or dendritic morphology. A relatively constant ratio of CD1a + LC to CD45R + cells (2:1) was seen. These results demonstrate the existence of intraepithelial cells expressing antigens which are functionally important in T cell responses and which may provide local immunoregulatory influences.

Expression of MHC class II antigens (HLA DR, DP and DQ) by keratinocytes in oral lichen planus

The incidence and distribution of keratinocytes expressing the major histocompatability complex antigens HLA DR, DP and DQ and their relationship to the density of the inflammatory infiltrate was determined in lesions of oral lichen planus and normal mucosa using an immunoalkaline phosphatase technique. Seven of eight biopsies of lichen planus showed evidence of keratinocyte HLA DR expression but the pattern was variable both within and between biopsies. A significant increase in density of lymphocytes was found beneath those areas showing HLA DR expression throughout the prickle cell layer compared with those areas showing patchy or no expression. No evidence for keratinocyte expression of HLA DP or DQ was found. These results suggest that expression of HLA DR by keratinocytes in lichen planus may be induced by the lymphocytic infiltrate perhaps as a result of interferon gamma production. The functional significance of such MHC Class II expression remains unknown.

Phenotypic characterization of mononuclear cells and class II antigen expression in angular cheilitis infected by Candida albicans or Staphylococcus aureus

In the present study we characterized the phenotypes of infiltrating mononuclear cells in angular cheilitis lesions to further explore the pathogenesis of this disorder. Frozen sections from lesions infected by Candida albicans and/or Staphylococcus aureus were subjected to immunohistochemical analysis utilizing monoclonal antibodies directed to subsets of T-lymphocytes, B-lymphocytes, and macrophages. In addition, the expression of Class II antigens (HLA-DP, -DQ, -DR), the interleukin 2- and transferrin-receptors was studied on resident and infiltrating cells. An intense infiltration of T-lymphocytes was accompanied by expression of Class II antigens on the epidermal keratinocytes in lesion infected by Candida albicans. The Staphylococcus aureus infected lesions displayed a diffuse infiltration of T-lymphocytes but virtually no expression of Class II antigen by epidermal keratinocytes. These observations suggest that the cell-mediated arm of the immune system is involved in the inflammatory reaction of lesions infected by Candida albicans. In addition, the present study confirms that epidermal expression of Class II antigens is closely related to the type and magnitude of the infiltrating T-lymphocyte. Finally, these findings indicate that the type of inflammatory reaction in angular cheilitis is primarily dependent on the isolated microorganism, although the clinical pictures of the disorder are virtually identical.

Oral lesions of lupus erythematosus patients in relation to other chronic inflammatory oral diseases: an immunologic study

The nature and distribution of mononuclear cells in non-ulcerated oral lesions of discoid (DLE) and systemic lupus erythematosus (SLE), were investigated and compared to other chronic inflammatory oral diseases (lichen planus (LP), contact lesion (CL), unspecified inflammation (UI), geographic tongue (GT), and leukoplakia (LK). For this purpose an immunoperoxidase technique based on staining with monoclonal antibodies was employed. In most LE specimens examined infiltrating cells consisted predominantly of a mixture of T cells (Leu 3a+ and Leu 2a+) that were distributed in the lamina propria, the submucosa, and occasionally also in the epithelium. In general, only few B cells were detected while macrophages were more frequent. In all LE specimens examined beta 2-microglobulin expression was observed on a large proportion of cells including infiltrating mononuclear cells as well as resident keratinocytes. In addition, most infiltrating cells displayed MHC Class II antigens according to a pattern HLA-DR greater than DQ greater than DP. Interestingly, expression of Class II antigens was also observed on epithelial keratinocytes but was restricted to HLA-DR and -DP gene products (DR much greater than DP). HLA-DQ expression was never observed on keratinocytes. In most LE specimens studied a small proportion (less than 5%) of inflammatory cells had detectable interleukin-2 receptors (IL-2R) and/or transferrin receptors (transf-R). However, expression of transf-R was also observed on basal epithelial cells, being more pronounced in DLE than in SLE lesions. The above staining patterns observed in LE lesions, when compared to other chronic inflammatory oral lesions, did not disclose any striking differences that could support the specific diagnosis of LE. However, the findings of Class I and II MHC gene products on oral keratinocytes suggest an important accessory role for these cells in directing the migration of activated lymphoid cells in the epithelium in chronic inflammatory lesions of the oral mucosa.

Immunohistochemical analyses of autoimmune sialadenitis in man

The immunoreactivity pattern for different monoclonal antibodies to cytokeratins and to vimentin in epimyoepithelial islands typical for glands of patients with Sjögren's syndrome has been compared with that of normal parotid gland tissue. Two types of epithelial island cells were observed: one had an intermediate filament protein pattern similar to that of ordinary duct epithelial cells of normal parotid gland. The other had an intermediate filament protein pattern typical of myoepithelial and/or basal duct cells in normal glands. Thus, we conclude that the islands are composed of a mixed population of gland cells on the basis of their content of cytokeratins or of cytokeratins and vimentin. These cells might originate from pluripotential reserve cells or from ordinary duct, myoepithelial and/or basal duct cells which may have undergone metaplasia.

Analysis of class II antigen expressing cells in cholesteatoma epithelium

The present morphological study was designed to evaluate the significance of Langerhans cells in the pathogenesis of cholesteatoma. Biopsies of middle ear cholesteatomas were examined for Langerhans' cells expressing HLA-DR and anti-Leu 6 antigens by immunohistochemistry using monoclonal antibodies. No apparent difference in number of cells was observed when epithelium of cholesteatoma was compared with epithelium of healthy ear canals. Expression of HLA-DR antigens was detected on keratinocytes in Aspergillus flavus infected epidermis, used as a control tissue. This finding indicated an increased immunosurveillance of this tissue. However, no such expression of HLA-DR antigens was detected on epidermal cells of cholesteatomas. The results of the present study did not support the hypothesis of Langerhans' cells as having a primary role in the development of cholesteatoma.

Epidermal Langerhans cells, dermal dendritic cells, and keratinocytes in viral lesions of skin and mucous membranes: an immunohistochemical study

We wanted to evaluate the eventual expression of viral antigens and MHC class II products by keratinocytes as well as the alterations of epidermal Langerhans cells and dermal dendritic cells in viral lesions of skin and mucous membranes. Therefore we investigated 68 biopsy specimens of protracted viral lesions, such as warts, condylomas, and mollusca contagiosa, and of rapidly resolving viral lesions such as herpes simplex virus infection. For this we used immunohistochemical staining techniques and several monoclonal and polyclonal antisera. In most cases investigated viral antigens (human papilloma virus antigens or herpes simplex virus type 1 antigens) could be demonstrated in keratinocytic nuclei. Except for a few viral lesions in which epidermal Langerhans cells were rather numerous, epidermal Langerhans cells were reduced in number or absent in almost all viral lesions. Moreover, epidermal Langerhans cells and dermal dendritic cells showed changes in morphology, distribution, and immunophenotype. These alterations may be caused by a toxic effect of the virus on dendritic cells. HLA-DR+ keratinocytes could be identified in few viral lesions only; HLA-DQ+ keratinocytes were not seen. Possible explanations for this lack of MHC class II expression by keratinocytes are discussed.