Immunohistochemical characterization of the thymic microenvironment

Summary The epithelial framework of the human thymus has been studied in parallel by immunohistochemical methods at the light- and electron-microscopic levels. Different monoclonal antibodies were used, reacting with components of the major histocompatibility complex, keratins, thymic hormones and other as yet antigenically undefined substances, which show specific immunoreactivities with human thymus epithelial cells.The electron-microscopic immunocytochemical observations clearly confirm microtopographical differences of epithelial cells not only between the thymic cortex and medulla, but also within the cortex itself. At least four subtypes of epithelial cells could be distinguished: 1) the cortical surface epithelium; 2) the main cortical epithelial cells and thymic nurse cells; 3) the medullary epithelial cells; and 4) the epithelial cells of Hassall's corpuscles.The various epithelial cell types of the thymus display several common features like tonofilaments, desmosomes and some surface antigens as demonstrated by anti-KiM3. In other respects, however, they differ from each other. The cortical subtype of thymic epithelial cells including the thymic nurse cells shows a distinct pattern of surface antigens reacting positively with antibodies against HLA-DR (anti-HLA-DR) and anti-21A62E. Electron-microscopic immunocytochemistry with these antibodies clearly reveals a surface labeling and a narrow contact to cortical thymocytes particularly in the peripheral cortical regions. An alternative staining pattern is realized by antibodies to some antigens associated with other subtypes of thymic epithelial cells. Medullary epithelial cells as well as the cortical surface epithelium react likewise positively with antibodies to special surface antigens (anti-Ep-1), to special epitopes of cytokeratin (anti-IV/82), and to thymic hormones (anti-FTS). The functional significance of distinct microenvironments within the thymus provided by different epithelial cells is discussed in view of the maturation of T-precursor cells.Glossary of Abbreviations Anti-X anti-X antibody - APUD-cells amine precursor uptake and decarboxylation (gastro-intestinal endocrine cells) - DAB diamino-benzidine - DMSO dimethyl sulfoxide - FTS facteur thymique sérique - HLA-A, B, C human leucocyte antigen, A, B, C-region related - HLA-DR human leucocyte antigen, D-region related - IDC interdigitating cell - MHC major histocompatibility gene complex - PBS phosphate-buffered saline - TNC thymic nurse cell This investigation was supported by grants from the Deutsche Forschungsgemeinschaft, and its Sonderforschungsbereich 111Fellow of the Alexander von Humbold-Stiftung, Institute of Pathology, University of Würzburg, Federal Republic of GermanyThe authors appreciate the contribution of human thymus tissue from Professor Alexander Bernhard, Abteilung kardiovasculäre Chirurgie der Universität Kiel; the gift of monoclonal antibodies from Dr. M.J.D. Anderson, Dr. M. Dardenne and Dr. H.J. Radzun; and the excellent technical assistence of Mrs. O.M. Bracker, Mrs. H. Hansen, Mrs. R. Köpke, Mrs. M. v. Kolszynski, Mrs. J. Quitzau, Mrs. H. Siebke, and Mrs. H. Waluk     

The use of EMG biofeedback with insulin-dependent diabetic patients

A recent report on the use of EMG biofeedback with an insulin-dependent diabetic is discussed. An examination of the role of EMG biofeedback in the management of carbohydrate metabolism is presented. While still an empirical question, it is concluded that EMG biofeedback will prove most useful in cases where a demonstrable relationship between stress and carbohydrate metabolism is evidenced.     

Immunological detection of a cysteine protease in the skin and other tissues

Summary Monospecific antibody directed to cysteine protease of 2-day-old rat epidermis recently characterized as being different from the proteases previously reported was produced in rabbits. By immunofluorescence microscopy and immunoperoxidase staining with an avidin-biotin-peroxidase method the protease was found to be present in the epidermis of rodents of different ages as well as that of humans, but not in the dermis. The staining in germinative cells was more intense than in cells in the superficial layers. It appeared as irregular patches in the nuclei and stained more diffusely in the cytoplasm where small granular components, strongly stained, were identified. The staining patterns in granular cells showed accumulation of the antigen in a granular form. The morphology and distribution of granules resembled those of keratohyalin-like granules in the nucleus and dense homogenous deposits in the cytoplasm. In cornified cells the reaction product was localized by the plasma membrane where concentration of the dense homogenous deposits occurred, suggesting that the cysteine protease is one component of the unique and characteristic structure of differentiated keratinocytes. In addition, the cysteine protease antigen having the same molecular weight as the epidermal enzyme was detected in liver, kidney and lung indicating a wider tissue distribution of the protease. The significance of the protease in regulation of cellular functions remains to be investigated.     

Localization and characterization of T-cell subpopulations and natural killer cells (HNK 1+ cells) in the human tonsilla palatina

Summary In the present study attention was focussed on several lymphoid subpopulations and specific stationary cells of the human tonsilla palatina. They were labeled at the light- and electron-microscopic levels by means of monoclonal antibodies to cell surface antigens. Cells resembling interdigitating cells (IDC-like cells) within the crypt epithelium and the interdigitating cells in the parafollicular T-cell region express the HLA-DR antigen. This fact suggests a relationship between these two populations of cells. Both cell types were frequently found in close contact to T-helper cells labeled with Anti-Leu 3a. This fact is discussed as a confirmation of earlier suggestions that the tonsillar crypt epithelium serves as T-cell region. Cytotoxic/ suppressor-T cells (OKT 8 ⁺) and Leu 7-positive cells do not appear to contact interdigitating cells. Anti-Leu 7 is a monoclonal antibody, that defines a differentiation antigen shown to be selectively expressed on human natural killer cells (NK-cells). With the use of the immuno-electron-microscopic labeling method it was possible to analyze the ultrastructure of this lymphoid subpopulation. Two morphologically distinguishable subtypes of Leu 7-positive cells populate different microenvironments: The Leu 7-positive large-granular lymphocyte was predominantly found in the crypt epithelium, while numerous Leu 7-positive cells located in the germinal centers had the appearance of small lymphocytes. This finding is discussed in favour of distinct phenotypes representing different stages in a differentiation pathway of the maturing NK-cell: Small Leu 7-positive lymphocytes in the germinal centers are supposed to be functionally inactive precursors, and only the Leu 7-positive large granulated lymphocytes in the crypt epithelium may represent differentiated active NK-cells. This interpretation is in agreement with the observation that the tonsilla palatina, in spite of containing numerous Leu 7-positive cells, shows only low NK-activity against tumor cells.Glossary of Abbreviations used in this Paper DAB diamino-benzidine - DMSO dimethyl sulfoxide - HLA human leucocyte antigen - HLA-DR human leucocyte antigen, D-region related - Ia-antigen immune-associated antigen of the MHC - IDC interdigitating cell - IDC-like cell cell that resembles an interdigitating cell - LGL large granular lymphocyte - MHC major histocompatibility gene complex - NK-cell natural killer cell - PBS phosphate-buffered saline