Follicular dendritic cells in normal and infected human appendix

Follicular dendritic cells (FDCs) that reside within the lymphoid follicles play a central role in humoral immunity. They bind immune complexes and present antigen to follicular B cells and in the generation of B cell memory. This study aims to demonstrate the distribution of CD35 positive FDCs in normal and infected appendix by immunohistochemistry. Four normal and 5 infected appendix specimens were used for the study. Tissues collected were processed for immunohistochemistry, stained with mouse antihuman CD35 monoclonal antibody using the Polymer - HRP Detection System. Double immunostaining was done with mouse antihuman CD20 monoclonal antibody to find out the association CD35 positive Langerhans cells with B lymphocytes. Cells were viewed under the light microscope (Olympus DP21). In the normal appendix, CD35 positive FDCs were present in a reticular pattern in the germinal centre of the follicle. In acute appendicitis, the lymphatic follicles were not intact and FDCs were scattered in the mucosa of the appendix. Few discrete CD35 positive cells were seen surrounding the intestinal glands. CD20 positive B lymphocytes were noted in the lymphatic follicle, interfollicular areas, around the crypts and in the lamina propria. Apposition of CD35 and CD20 cells was noted. The dendrites of FDCs demonstrated in the follicles of appendix displayed an antigen-retaining reticulum which aids in trapping of immune complexes. Their association with CD20 positive B cells confirm the role of appendix in humoral immunity

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Ultrastructural demonstration of antigen presenting cells in human uterine tube

Langerhans cells (LCs) are the predominant antigen-presenting cells distributed in the mucosa of various organs with high antigenic exposure. They capture antigens, process and present them to the T lymphocytes. LCs are known to be present in the human female reproductive tract. Very few studies have demonstrated the presence of LCs in human uterine tubes. The aim of the present study was to demonstrate the morphology and distribution of LCs in the normal and postpartum human uterine tube by electron microscopy. Tissues from two normal and three postpartum uterine tubes were studied under electron microscopy. The epithelium of the uterine tube varied from simple ciliated columnar epithelium to stratified ciliated columnar epithelium. LCs with a single dendritic process could be identified in the epithelium. The dendritic process displayed the unique Birbeck granules in the cytoplasm. Close apposition of LCs with the intraepithelial lymphocytes was noted. In addition, there were M cells in the epithelium of the normal uterine tube. In the lamina propria, LCs with two or three processes were present which displayed Birbeck granules. They were in close association with lymphocytes as well as with the endothelial cells of the capillaries. A few high endothelial venules (HEVs) were present in the lamina propria of the postpartum uterine tube. The presence of LCs, M cells and HEVs in the uterine tube indicates that the uterine tube is an integral part of mucosa-associated lymphoid tissue

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Morphological study of dendritic cells in human cervix by zinc iodide osmium method.

BACKGROUND: Dendritic cells (DCs) are a heterogeneous population of antigen presenting cells that have been identified in several tissues including the female reproductive organs. The aim of the present study is to demonstrate the morphological differences of dendritic cells in normal human exocervix using the Zinc Iodide Osmium (ZIO) procedure. MATERIALS AND METHODS: Normal cervical tissues obtained from nine patients who underwent abdominal hysterectomies for various ailments were processed for histochemical study. Six microns thick serial sections were taken and viewed under a light microscope. The diameters of the cells were measured under a magnification of 40x using the Cellsens image analysing software and analysed using SPSS version 16. RESULTS AND CONCLUSION: In the normal human exocervix, a greater density of ZIO-positive DCs was noted in the epithelium and subepithelium and their distribution was not uniform. In some areas of epithelium, the ZIO-positive cells in the basal layer showed a typical dendritic morphology, while the cells in the intermediate and superficial layers were nondendritic polygonal cells. Intraepithelial capillaries were noted, which were surrounded by ZIO-positive nondendritic polygonal cells. There was significant difference in the mean diameters of typical DCs (8.61±1.86 µm) and nondendritic polygonal cells (10.97±1.93 µm). In the subepithelium the DCs had typical morphology and their distribution varied. ZIO positive DCs were noted in the epithelium and cervical glands of endocervix also. In conclusion, the human cervix has different subsets of ZIO positive DCs with varied distribution. Their functional role has yet to be defined.

Different subsets of Langerhans cells in human uterine tubes and uterus.

AIM: Langerhans cells (LC) are antigen-presenting cells present in tissues with high antigenic exposure. Their role in the upper female reproductive tract is not fully understood. This study aims to determine the distribution and morphology of LC in the normal and post-partum human uterine tubes and uterus by staining with the specific LC markers, CD1a and zinc iodide-osmium (ZIO), and to determine their association with helper and cytotoxic T cells. MATERIAL AND METHODS: Normal and post-partum uterine tube and uterine specimens were stained with CD1a and ZIO and their morphology and distribution noted. Double immune staining with CD1a-CD4 and CD1a-CD8 in post-partum uterine tube were also done. RESULTS: It was noted that CD1a-positive cells were significantly fewer and smaller in diameter than ZIO-positive cells in the uterine tube and both types of cells were significantly more prevalent in post-partum tubes. Perivascular clusters of ZIO-positive cells were seen in the post-partum tubes. Close association of CD1a-positive cells with CD4- and CD8-positive T cells was noted in the post-partum uterine tube. In the uterus, scanty CD1a-positive cells were present in the surface and glandular epithelium and endometrial stroma. ZIO-positive cells were absent. CONCLUSION: This study suggests that CD1a-positive and ZIO-positive cells may be different subsets of LC that are needed for presentation of antigen to immunocompetent cells. Their respective functions are yet to be determined.

Langerhans cells in the human tympanic membrane in health and disease: a morphometric analysis.

HYPOTHESIS: The normal tympanic membrane contains Langerhans dendritic cells, and they play a role in the pathogenesis of chronic suppurative otitis media. BACKGROUND: The presence of Langerhans dendritic cells in the normal tympanic membrane is disputed. However, they have been identified in tympanic membranes of patients with otitis media. A quantitative analysis of the distribution and morphology of these cells in the types of chronic suppurative otitis media has not been undertaken. METHODS: Samples of normal cadaveric tympanic membranes and those from patients with chronic suppurative otitis media of the tubotympanic and atticoantral varieties were stained with the immunohistochemical marker CD1a. The number of cells per unit length of basement membrane, diameters of cells, and number and length of dendritic processes were compared between the groups. RESULTS: CD1a-positive Langerhans dendritic cells were present in the normal tympanic membrane. The number of cells per unit length of basement membrane, diameters of cells, and the length of dendritic processes increased significantly in tubotympanic disease and in atticoantral disease, the difference being more pronounced in the latter form of otitis media. CONCLUSION: Langerhans cells are present in the normal tympanic membrane, and they probably play differing roles in the pathogenesis of tubotympanic and atticoantral forms of chronic suppurative otitis media.

Route of lymphocyte migration through the high endothelial venule (HEV) in human palatine tonsil.

Eleven palatine tonsils were collected from subjects who underwent tonsillectomy in Christian Medical College Hospital and the route of migration of lymphocytes through the high endothelial vessel was studied under EM. In the interendothelial route, migration of a lymphocyte through HEV wall began with the adhesion of a lymphocyte to the surface of endothelial cells by means of a short cytoplasmic projection in the vicinity of intercellular space. The projection extended into the cleft between adjacent endothelial cells. The lymphocyte migrated through HEV by diapedesis. After the lymphocyte had traversed the interendothelial space, it occupied the subendothelial space. In the transendothelial route, migration of a lymphocyte through HEV was initiated by adherence of the lymphocyte to the endothelial cell. The adherent lymphocyte compressed or invaginated into the cytoplasm of the endothelial cell, entered the endothelial cell, was completely enclosed within the endothelial cell cytoplasm, and emerged from the endothelial cell to occupy the subendothelial space. Evidence is presented from static transmission electron microscopic pictures for the migration of lymphocytes by both interendothelial and transendothelial routes through the high endothelial venule.