The ultrastructure of human gingival Langerhans cells in health and disease

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.

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

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

Density of CD1a-labeled Langerhans' cells in normal human gingiva and in nifedipine- and immunosuppressive medication-induced gingival overgrowth

BACKGROUND

The purpose of this study was to compare the distribution of Langerhans' cells in normal human gingiva and in nifedipine- and immunosuppressive medication-induced gingival overgrowth by means of an immunohistochemical study.

METHODS

Gingival samples were collected from 11 nifedipine-medicated cardiac patients, 22 triple-medicated (azathioprine, prednisolone, and cyclosporin A) renal transplant recipients, and 28 generally healthy individuals. Patients were grouped into the immunosuppression group, the combined immunosuppression and nifedipine group, the nifedipine group, and the generally healthy control group. Five microm-thick cryostat sections were stained with monoclonal antibody (mAb) for CD1a using an avidin-biotin-enzyme complex (ABC) method. Numbers of CD1a-labeled cells/mm2 were determined in 6 areas: oral epithelium, oral sulcular epithelium, sulcular epithelium, middle connective tissue, connective tissue beneath the oral epithelium, and connective tissue beneath the sulcular epithelium. Significances of differences between the groups were tested by means of the Kruskall-Wallis test, and significances of differences between pairs of results by the Mann-Whitney U-test and the t test.

RESULTS

Numbers of CD1a-labeled cells were significantly lower in the medicated groups than in controls in all 3 epithelial areas (P <0.0001) and in the connective tissue beneath the sulcular epithelium (P <0.0021). There were significantly fewer CD1a-labeled cells in the sulcular epithelium in the nifedipine group than in the other medication groups.

CONCLUSIONS

The reduced numbers of CD1a-labeled cells found in nifedipine-induced gingival overgrowth were similar to the reduced numbers of CD1a-labeled cells in gingival overgrowth associated with immunosuppressive medication.

Three-dimensional appearance of Langerhans cells in human gingival epithelium as revealed by confocal laser scanning microscopy

Detailed three-dimensional morphological information of the cell without distortion due to thin sectioning can be obtained from thick sections using a confocal laser scanning microscope. Here that microscope was used to evaluate human gingival Langerhans cells stained with anti-CD1a antibody. Optical sectioning and reconstruction by laser scanning microscopy revealed not only three-dimensional aspects of Langerhans cells but also spatial information on the distribution of their dendritic processes towards the gingival surface. The orientated configuration of those processes may reflect the reaction of the gingival Langerhans cell to the surrounding moist environment containing antigenic stimuli originating in saliva.

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.

Distribution of ICAM-1, LFA-3 and HLA-DR in healthy and diseased gingival tissues

Cell adhesion molecules are involved in recognition and effector aspects of the host response, including the control of migration of leukocytes into inflammatory sites. In this study we have demonstrated that the distribution of three cell-surface molecules involved in cell interactions, ICAM-1, LFA-3 and HLA-DR is distinct and different in healthy and diseased gingival tissue. ICAM-1 was consistently expressed by junctional epithelial cells in healthy gingiva and by pocket epithelium in diseased gingiva but was not detectable on the majority of keratinocytes in external gingival epithelium. ICAM-1 was also expressed by endothelial cells of gingival blood vessels and a subset of leukocytes in the infiltrated connective tissue in both healthy and diseased gingiva. HLA-DR and LFA-3 were also expressed by epithelial cells and endothelial cells but in patterns which were distinctly different from ICAM-1.

Morphological variations and population density of membrane-coating granules in human gingival sulcular epithelium

Surgically excised specimens of sulcular wall with minimal inflammatory response as judged by clinical then histological criteria were processed for electron microscopy. The specimens were divided into crestal, middle and cervical areas of the sulcular epithelium. The highest concentration of membrane-coating granules was found in the upper spinous cell layers of sulcular epithelium. The profiles of these granules showed examples of both classical keratinized (lamellated) and non-keratinized (non-lamellated) forms but also other appearances that were not derived from them through differences in the plane of section. The population of granules decreased between the crestal and cervical zones, and the decrease in number was marked for the lamellated granules. This decrease in numbers of membrane-coating granules, together with the wider intercellular spaces, may be the reason why the sulcular epithelium is most permeable in the cervical region.

The human gingival indeterminate cell revisited

Electron microscopic examination of over 100 dendritic cells in human keratinized gingiva has shown that the indeterminate cells are not a separate cell type. This approach disclosed the sources of error which have led to the commonly held, but erroneous, view that there exist numerous indeterminate cells in this epithelium. Two interesting differences were found between gingival and epidermal Langerhans cells. The number of Birbeck granules in the former cells can be extremely low while they occur frequently in the epidermal cells, and granules in their formative stage are commonplace in the gingival cells but rare in the epidermal cells.

Langerhans cells of human mucosa

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

Immunohistochemical study of neurochemical markers in gingiva obtained from periodontitis-affected sites

Immunohistochemical methods have been used to study the occurrence of neuronal markers in human gingiva from periodontitis-affected sites. In periodontitis-affected buccal gingiva densely distributed neurofilament (NF)-immunoreactive (IR) fiber bundles were observed in the deeper parts of the propria, while NF-IR single fibers occurred in the superficial propria and occasionally in the buccal epithelium. Periodontitis-affected gingiva obtained from interproximal sites showed only sparsely distributed NF-IR fibers. Single nerve fibers immuno-reactive to the peptides substance P and calcitonin gene-related peptide occurred close to or within the epithelium in both buccal and interproximal gingiva. Around blood vessels neuropeptide Y-, peptide histidine-isoleucine amide- and vasoactive intestinal polypeptide-IR fibers were occasionally observed, while clusters of gamma-melanocyte-stimulating hormone-IR cells were found in the propria, in addition to gamma-melanocyte-stimulating hormone IR nerve fibers. Somatostatin-IR dendritic cells were seen in epithelium and propria of buccal and interproximal gingiva, although a high variability in the number of SOM-IR cells was observed. All neuronal markers studied showed a similar distribution in material obtained from young patients with clinically healthy gingivae, although the number of NF-IR fibers in the propria in these subjects was lower. The results demonstrate that in gingiva obtained from periodontitis-affected sites several different biologically active peptides occur in both nerve fibers and cells. At least some of these substances could possible play a role in the inflammatory process. However, since clinically normal gingiva was shown to contain nerve fibers and cells expressing immunoreactivity to the substances studied, no unique periodontitis-induced expression of the neuronal markers studied was found. Thus, any alteration of these substances during the periodontitis process remains to be elucidated.

Human gingival Langerhans cells as accessory cells in mitogen induced T cell responses

Peripheral blood and gingival tissue was collected from patients undergoing surgery for the treatment of periodontal disease. Both unfractionated peripheral blood mononuclear cells and a T cell-enriched, monocyte-depleted lymphocyte population were isolated from the blood samples while a gingival epithelial cell suspension was prepared from the oral aspect of the gingival tissue. The blood cells (1 X 10(5)) were then co-cultured with the gingival epithelial cells (1 X 10(5) and 1 X 10(4)) in 200 microliters aliquots in microtitre trays for three days to see if the epithelial cells could act as accessory cells in the lymphocyte response to the mitogen, phytohaemagglutinin (PHA). Lymphocyte proliferation was assessed by measuring the uptake of [6-3H] thymidine during the last 18 hours of culture. Removal of monocytes from peripheral blood mononuclear cells led to a significant, but not total, reduction in the proliferative response to PHA. When gingival epithelial cells were added to the T cells they restored their response to PHA in a dose dependent fashion. As Langerhans cells were the only potentially immunocompetent cells seen in the epithelial cell suspensions, it is concluded that these cells are acting as accessory cells in the T cell response to PHA.

Distribution of Langerhans cells in clinically healthy human gingival epithelium with special emphasis on junctional epithelium

Twenty-one biopsies of clinically healthy marginal gingiva from children, who performed conventional oral hygiene but received no additional professional prophylaxis, were studied in order to obtain information on distribution and density of Langerhans cells (LC) in the oral gingival epithelium (OGE), the sulcular epithelium (SE) and the junctional epithelium (JE). A simple freeze-separation technique was found to create acceptable histomorphology of JE in specimens obtained adherent to teeth, while partially and non-adherent ones were rejected. The majority of LC in OGE were highly dendritic and stained intensively with OKT6 monoclonal antibodies. The distribution was network-like with a density of 21.0 +/- 3.2 LC/0.1 mm2 cross-sectional epithelial area. A similar although less dense distribution was found in SE (8.6 +/- 3.0 LC/0.1 mm2). These observations confirm previous findings. In JE 2 groups of LC were identified: 1) Weakly stained LC with very few and short dendrites distributed in a scattered way (2.8 +/- 1.4 LC/0.1 mm2) in the apical three-fourths of JE in most specimens. Present evidence suggests that these cells might be immature cells of Langerhans lineage. 2) Clusters of LC (9.4 +/- 2.9 LC/0.1 mm2) with dendrites of moderate lengths and numbers and a varied fluorescence intensity; they were found in a few specimens in the coronal one-fourth of JE and at the border zone to SE. Such clusters might represent genuine variation in the distribution of LC or reactions to initial/early plaque formation.