Langerhans cells in oral epithelium of chronically inflamed human gingivae

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.

Physiology and pathophysiology of dendritic cells

Dendritic cells are antigen-presenting cells derived from the hematopoietic stem cell. The dendritic cell family includes Langerhans' cells (CD1a-positive dendritic cells of the skin), and antigen-presenting cells that are found in the lymphoreticular system and throughout the organ parenchyme. Dendritic cells play a key role in both the primary and secondary immune responses. Several studies indicate that these cells participate in antitumor immunity, tumor surveillance, graft-versus-host disease, and in the pathogenesis of clinical syndromes of unknown origin or those induced by viruses, such as the human immunodeficiency virus. Different disorders are characterized by an abnormal proliferation and accumulation of dendritic cells; for example, the Langerhans' histiocytes, which accumulate in Langerhans' cell histiocytosis. In this review the immunophenotypic, morphological, and functional characteristics of the dendritic cell family is described. The clinical and laboratory studies suggesting a unique role for these cells in various syndromes and diseases are reviewed. The Langerhans' cell histiocytoses and the malignant disorders associated with transformation of cells belonging to the dendritic cell family, are discussed.

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.

Epithelial expression of HLA class II antigens and Fc gamma receptors in patients with adult periodontitis

The distribution of HLA class II (DR, DP, DQ) and Fc gamma R (I, II, III) was analyzed in the epithelia of patients with advanced marginal periodontitis using cryostat sections incubated with monoclonal antibodies (MoAb) against the Langerhans cell (LC) (CD1a) and various subtypes of HLA class II and Fc gamma R, and the indirect immunofluorescence technique. In the oral gingival epithelium (OGE), LC were concentrated subjacent to the connective tissue papillae, while in the pocket epithelium (PE), they were most abundant at the gingival margin. HLA-DP, DQ, and DR stained LC in both OGE and PE. HLA-DQ+ LC were significantly fewer than DP+ and DR+ LC. HLA-DR also stained keratinocytes (KC) in the whole extension of both OGE and PE. HLA-DP was also observed on KC, but not HLA-DQ. Fc gamma R II stained both LC and focal areas of KC. In PE FC gamma R II+ LC were concentrated near the bottom of the pocket, while in the OGE, they were concentrated at the gingival margin. Fc gamma R III was present only on KC, especially in the basal and suprabasal layer. The results indicate that the epithelial cells are actively involved in the development and maintenance of the inflammation of periodontal disease.