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H Wekerle

Publications and source records attributed to H Wekerle.

At least 199 records · Page 11Linked to original sources
PubMed1981

Autoimmune rat T lymphocytes monospecific for acetylcholine receptors: purification and fine specificity.

We prepared highly purified acetylcholine receptor (AChR)-specific T lymphocytes from rats with experimental autoimmune myasthenia gravis (EAMG). Inbred rats were primed with AChR frm 3 different sources: from the electric organs of Electrophorus electricus and Torpedo californica and from denervated rat muscle. After 20 to 30 days, lymphocytes from regional lymph nodes (primary cells) were challenged with soluble AChR in vitro. The activated blast cells were isolated by density gradient centrifugation and allowed to revert back to small secondary lymphocytes in the absence of antigen. These secondary anti-AChR cells were highly responsive to the type of AChR with which they had been primed. Their reactivity critically depended on help by syngeneic accessory cells. Anti-Electrophorus AChR primary and secondary cells cross-reacted detectably with rat AChR and vice versa, whereas anti-Torpedo AChR primary and secondary cells did not significantly cross-react with Electrophorus or rat AChR. Secondary T cells strongly reactive against rat AChR could be selected in vitro from Electrophorus AChR-primed populations by using rat AChR as selecting stimulant. These cells responded equally well against Electrophorus and rat AChR and thus include autoreactive T cell clones.

Animals↗
PubMed1981

Selective, immunologically nonspecific adherence of lymphoid and myeloid cells to Leydig cells.

In mixed lymphocyte-testis cell cultures, lymphoid cells form rosettes around a testis cell population. The rosette formation seems to reflect cell type specific, but not immune recognition, because: a) rosettes are formed only around Leydig, But not around other testis cells; b) most, if not all normal lymphoid cells can be bound by Leydig cells; c) in addition, Leydig cells bind presumably monoclonal lymphoid and myeloid tumor line cells, but no other cell types.

Animals↗
PubMed1980

Thymic nurse cells. Lymphoepithelial cell complexes in murine thymuses: morphological and serological characterization.

We describe a new cellular component of normal mouse thymuses, which is isolated by fractionated trypsin dissociation of minced thymus tissue followed by repeated unit gravity sedimentation. These cells are of unusually large size, with diameters of 30 mum and more. They represent cellular complexes of single large cells filled with high numbers of lymphoid cells. The majority of the engulfed lymphoid cells is not only fully intact, as judged by morphological criteria, but, moreover, includes a high proportion of mitotic figures. Electron microscopic investigations reveal the epithelial character of the large thymic nurse cells (TNC). The peripherally situated cytoplasmic tonofilament streams, and characteristic vacuoles filled with coarse, unidentified material, closely resemble cytoplasmic organelles found in the cortical reticuloepithelial cells described in situ. The internalized lymphocytes are located within caveolae lined by plasma membranes. These TNC caveolae are completely sequestered, and have lost any communication with the extracellular space, as demonstrated by the inability of an electrondense marker, cationized ferritin, to diffuse into the perilymphocytic clefts. The structural interactions between the membranes of the engulfed thymocytes with the surrounding TNC caveolar membranes were investigated both in ultrathin sections and in freeze-etch preparates. Two distinct contact types between both membranes were discerned: (a) complete, close contact along the entire lymphocyte circumference, and (b) more frequently, contact restricted to discrete, localized areas. Judging from their size and distribution, the localized contacts could correspond particle aggregates of freeze-etch preparates, which morphologically resemble certain stages of gap junction. Furthermore, we regularly found square arrays of particles of uniform size, which so far have been thought to be typical for cell membranes actively engaged in ion exchange. Tight junction-like particle arrays, which were present on TNC outer membranes, and probably represented disrupted contacts between adjacent TNC in the intact tissue, could not be found on caveolar or lymphocyte membranes. Finally, one of the most conspicuous specializations of the TNC caveolar membrane were membrane invaginations, which were arranged mainly in groups, and which probably reflect endo- or exocytotoxic events. We investigated the surface antigen phenotype of TNC by indirect immunofluorescence, with monoclonal antibodies against determinants of H-2- complex subregions as well as against lymphocyte differentiation markers. Semiquantification was reached with flow cytofluorimetry, followed by morphological control by fluorescence microscopy. The surface antigen formula of TNC is: Ig(-), Thy-l(-), H-2K(++), I-A (++), I-E/C(+), H-D(++), Ly-1(-), Ly-2(-), Qat-4(-), Qat-5(-), and peanut agglutinin (PNA)(-). Thymic macrophages, which were identified by double fluorescence, with rhodamine- coupled zymosan as a phagocytosis marker, were serologically identical with TNC. Free thymocytes, in contrast, had the following antigen formula: Ig(-), Thy-1(++), H-2K(+/-), I-A(-), I-E/C(-), H-2D(+/-), Ly-1(+/-), Ly-2(+), Qat- 4(-), Qat-5(-), and PNA(+). The unprecedented finding of high numbers of dividing thymocytes sojourning within thymic epithelial cells, and the particular specializations of the TNC caveolar membranes surrounding these engulfed thymocytes is the basis of a hypothesis that postulates that an intraepithelial differentiation cycle is one essential step in, intrathymic T lymphocyte generation.

Animals↗
PubMed1980

Chemiluminescence and immune cell activation. II. Enhancement of concanavalin A-induced chemiluminescence following in vitro preincubation of rat thymocytes; dependency on macrophage-lymphocyte interaction.

The immediate chemiluminescence (CL) response to concanavalin A (Con A) of rat thymocytes is enhanced 10 to 20-fold when the cells are preincubated in serum-free medium for 5--20 h. During this period, multiple encounters between lymphocytes and macrophages occur which morphologically appear as rosettes or grape-like cell aggregates. Additionof bone marrow-derived macrophages increases the number of cell aggregates and also the CTL response to Con A. Paradoxically, removal of macrophage-containing cell aggregates after cocultivation leaves a pure thymocyte population which strongly responds to Con A with CL. Our results confirm that macrophage-depleted "competent" lymphocytes are capable of CL and, furthermore, that "competence" is gained during cocultivation with macrophages. We are therefore convinced that measurements of macrophage and lymphocyte CL are a powerful tool for further elucidation of lymphocyte differentiation and of interactions between macrophages and lymphocytes.

Animals↗
PubMed1979

Autoimmune interaction measured in a postlabelling microcytostasis assay.

A postlabelling microcytostasis assay was developed to assess primary immune interaction between normal rat lymphocytes and autologous testis cells. In this vitro model of experimental autoimmune orchitis (EAO) unprimed T cells respond to a Sertoli-like subpopulation of testis cells during a 4 day culture period. The T effector cells exert a cytostatic effect on the monolayer-forming target cells. The number of remaining target cells, which inversely correlates with the intensity of the autoimmune reaction, is quantified by 51Cr incorporation. The assay is performed in multiple well plastic plates which allow rapid harvesting by cutting off the bottoms of each well. The attached labelled target cells are directly measured on the bottoms without any further transfer step. The method is adapted for the EAO model but may be useful to study primary T cell interaction with any other monolayer-forming target cells.

Animals↗
PubMed1978

Immunological T-cell memory in the in vitro-induced experimental autoimmune orchitis: specificity of the reaction and tissue distribution of the autoantigens.

Immunological memory has been induced in vitro against testicular autoantigens by priming normal rat T lymphocytes against autologous testis cells, and by permitting the isolated blast cells to revert back to small secondary lymphocytes (secondary EAO cells) in the absence of the priming antigen. The secondary EAO cells vigorously respond in a secondary response when reconfronted with syngeneic testis or lymphoid cells. Their responsiveness to nonself stimulator cells is, however, reduced. Secondary cells derived from concanavalin A-stimulated blasts, do not show that pattern of specificity. The specificity of the secondary EAO cells is definite, and cannot be affected by further culture on allogeneic fibroblasts, which are antigenic for unprimed T lymphocytes. At least part of the autoantigens are determined by the major histocompatibility gene complex (MHC). Factors provided by the culture system do not appear to determine the specificity of this reaction. Only minor cell populations can restimulate secondary EAO cells. One of these populations is presumably phage-like cells within the lymphoid populations can elicit a secondary EAO response. Thus, the autoantigens relevant in the secondary EAO response are either MHC antigens restricted to these testicular and lymphoid subpopulations, or MHC antigens recognized in conjunction with organ-specific non-MHC determinants.

Animals↗
PubMed1978

In vitro induction of experimental autoimmune orchitis: characterization of a primary T lymhocyte response against testicular self antigens.

Lymphocytes from normal, young adult rats were autosensitized in vitro against trypsin-dissociated autologous testis cells. The autoimmune response had been assayed both by determination of the lymphocyte proliferation, using a (3H)thymidine incorporation test, as well as by determination of their specific cytostatic activity against monolayer-forming testis cells which was measured in a terminal 51Cr uptake assay. The actively responding cells in this system are T lymphocytes. Non-T cells can exert additional, non-specific cytostasis. The immune specificity of the in vitro experimental autoimmune orchitis (EAO) has been demonstrated on two levels. First, the responding T lymphocytes were found to specifically adhere around cells from one particular testis subpopulation which morphologically resemble Sertoli cells. The rosetting lymphocytes respond only to testicular self antigen, but not to allogeneic lymphocytes. Second, specificity to the effector T lymphocytes was revealed in transfer experiments. Autosensitized EAO effector T cells cytostatically affected only major histocompatibility gene complex (MHC)-compatible testis cells. Their reactivity against MHC-different testis cells or MHC-compatible nontesticular fibroblasts was significantly decreased which suggests both tissue as well as MHC specificity of the EAO response.

Animals↗
PubMed1978

Intrathymic pathogenesis of myasthenia gravis: transient expression of acetylcholine receptors on thymus-derived myogenic cells.

Differentiation of myogenic stem cells from undifferentiated thymic stem cells is thought to play a critical role in the pathogenesis of myasthenia gravis. The expression of membrane acetylcholine receptor (AChR) on the membranes of developing muscle clones in cultures of murine thymus reticulum was followed and found to be transient. AChR are first expressed shortly after fusion of myotubes. In subsequent stages of myogenic development, the density of homogenously distributed AChR is strongly increased, and, in addition, concentrated "hot spot" AChR areas appear. During further maturation, membrane AChR are lost. Highly mature myotubes (3 months in culture) lack substantial amounts of homogenous AChR, as well as hot spots.

Acetylcholine↗
PubMed1977

Intrathymic pathogenesis and dual genetic control of myasthenia gravis.

We propose a two-step model for the pathogenesis of myasthenia gravis. In the first step, primitive intrathymic stem-cells are induced by abnormal stimuli to differentiate to (abnormal?) myogenic cells. In the second step, immunocompetent T lymphocytes start an autoimmune reaction against these newly differentiated myogenic cells. The clinical stage is reached when autosensitised effector T lymphocytes leave the thymus and either infiltrate the synaptic spaces of peripheral muscles or participate in the formation of autoantibodies, causing the neuromuscular symptoms. At two points the pathogenesis is under genetic control--the first at the differentiation of the stem-cells to myogenic cells and the second at the immune responsiveness of the lymphocytes to these atypical intrathymic muscle cells.

Animals↗
PubMed1977

Recognition of alterations induced by early vaccinia surface antigens and dependence of virus-specific lysis on H-2 antigen concentration on target cells.

Specific recognition of antigens by cytolytic T lymphocytes sensitized to vaccinia virus was tested by monolayer adsorption. Adsorption was possible only on monolayers also expressing syngenic H-2 as viral antigens present during the sensitization phase. Vaccinia-virus-infected target cells were subjected to papain and neuraminidase treatment. H-2 antigenic determinants could be removed by papain treatment. Due to virus-specific inhibition of host-cell protein synthesis, reexpression of H-2 antigenic determinants did not take place, but viral surface antigens were resynthesized. Susceptibility of target cells to T-cell-mediated lysis was decreased after papain treatment. Substrains of vaccinia virus were used in order to define the minimal changes induced by vaccinia virus necessary for T-cell sensitization in vivo and target-cell lysis in vitro. When the immune response to a conditioanl lethal mutant strain of vaccinia virus was investigated, it could be demonstrated that expression of early surface antigens is sufficient for induction of the cellular immune reactions. These data were confirmed by inhibition studies with virus-specific antisera.

Animals↗
PubMed1976

Thymus-derived striated muscle clones. An ultrastructural analysis of cell differentiation.

Myogenic clones can be induced in thymus reticulum cultures from adult mice. We investigated the differentiation and maturation of myogenic cells by combined ultrathin section and freeze etching analyses. New insights into the development of cell membranes and cytoplasmic organelles will be discussed in the light of previous investigations of embryonic muscle cell cultures.

Animals↗