Bidirectional Interactions Between Thymocytes and Thymic Epithelial Cell Lines in Vitro (original) (raw)
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Developmental Immunology, 2002
In this work, the interaction between a rat cortical thymic epithelial cell (TEC) line (R-TNC.1) with nursing activity and thymocytes as well as BWRT 8 thymocyte hybridoma (TH) cells has been studied. The R-TNC.1 cell line significantly bound thymocytes and TH. Binding was stronger during the first 30 min of cell incubation and was followed by a progressive deadhesion. Among adherent thymocytes the proportion of apoptotic cells increased with culture time which was a consequence of higher capacity of the line for binding of apoptotic than viable cells and induction of apoptosis in a subset of adherent thymocytes. Emperiopolesis activity of this thymic nurse cell (TNC) line was manifested by engulfment of thymocytes as well as TH cells. A subset of viable intra-TNC thymocytes has been triggered to die by apoptosis, whereas other internalized thymocytes have been stimulated to proliferate, as measured by an increase in the percentage of cells in mitosis and higher incorporation of bro...
Cytokine crosstalk for thymic medulla formation
Current Opinion in Immunology, 2011
The medullary microenvironment of the thymus plays a crucial role in the establishment of self-tolerance through the deletion of self-reactive thymocytes and the generation of regulatory T cells. Crosstalk or bidirectional signal exchanges between developing thymocytes and medullary thymic epithelial cells (mTECs) contribute to the formation of the thymic medulla. Recent studies have identified the molecules that mediate thymic crosstalk. Tumor necrosis factor superfamily cytokines, including RANKL, CD40L, and lymphotoxin, produced by positively selected thymocytes and lymphoid tissue inducer cells promote the proliferation and differentiation of mTECs. In return, CCR7 ligand chemokines produced by mTECs facilitate the migration of positively selected thymocytes to the medulla. The cytokine crosstalk between developing thymocytes and mTECs nurtures the formation of the thymic medulla and thereby regulates the establishment of self-tolerance.
Cellular Immunology, 2004
Much debate has been generated about the existence of thymic nurse cells within the thymus. Until now, the authenticity of an epithelial cell capable of internalizing developing thymocytes within the thymic cortex has been in question. Here, we use the thymic nurse cell-speciWc monoclonal antibody, ph91, to deWne the in vivo location of thymic nurse cells. For the Wrst time, thymic nurse cells enclosing several thymocytes were detected in the subcapsular region of the thymic cortex in a "honeycomb-like" conWguration. In vitro studies show the internalization process using digitalized time-lapse microscopy. Internalized thymocytes have also been reported to interact with macrophages within the TNC complex. The cytoplasmic interaction between thymocytes and macrophages was detected using time-lapse microscopy. Using Xuorescence microscopy, we show polymerization of actin within macrophages at the contact point with thymocytes, which is indicative of an immunological synapse. MicroWlaments and microtubules within TNCs were shown to be associated with thymocyte binding and internalization, but neither interacted with macrophages. Also, we provide data to show that thymocytes are actively involved in the internalization process. These experiments show for the Wrst time the existence of thymic nurse cells within the thymic microenvironment. They provide a visual documentation of thymocyte uptake by thymic nurse cells, and deWne an interaction between thymocytes and macrophages within the TNC complex.
A Novel Adhesion Molecule in the Murine Thymic Microenvironment: Functional and Biochemical Analysis
Developmental Immunology, 1992
The rat monoclonal antibody (mAb) 4F1, raised against mouse thymic stromal cells, recognizes cortical epithelium in tissue sections of mouse thymus; however, in flow cytometry, activated leucocytes (T cells, B cells, and macrophages) and transformed thymocytes are also positive for the 4Fl-antigen (4F1-Ag). Western blotting, under both reducing and nonreducing conditions, demonstrates that the molecule to which 4F1 binds is expressed in four forms, 29, 32, 40, and 43 kD, all of which carry N-linked carbohydrate; and that the structure is identical on epithelium and lymphocytes. The 4F1-Ag on cortical epithelium is partially sensitive to PI-PLC treatment, whereas on transformed epithelial and lymphoid cell lines, it was resistant to this enzyme. The molecule, therefore, may exist in both transmembrane and phosphoinositol-linked forms. In functional blocking experiments, mAb 4F1 gave inhibition of both T-cell proliferation in MLR and of cytotoxic T-cell killing of alloantigenic targets; it also blocked adhesion of transformed thymocytes to thymic epithelial cells in vitro. These molecular and functional characteristics suggest that the 4F1-Ag is a novel adhesion molecule that may be involved both in intrathymic T lymphocyte differentiation and in peripheral T-cell function. Thymus, thymocytes, lymphocyte activation, PI linkage. 'Thymoma lymphoid cells and normal BALB/c thymocytes (10") stained in suspension using the immunofluorescence technique and analyzed by flow cytofluorimetry. The percentage of cells stained by other mAbs such anti-IA, anti-CD4, anti-CD8, and anti-Thyl.2 shown in comparison. Data from three independent experiments (mean %+standard deviation). bTypical of the 2/14 mice.
Mechanisms Involved in the Binding of Thymocytes to Rat Thymic Dendritic Cells
Developmental Immunology, 1996
The effects of monoclonal antibodies (mAbs) to cell-surface molecules, divalent cations, and various cell-signaling and metabolic inhibitors on the binding of thymocytes to rat thymic dendritic cells (TDC) were studied using a rosette assay. It was found that TDC/thymocyte adhesion was stronger and faster at 37℃ than at 4℃. Flow cytometric analysis demonstrated that bound thymocytes were predominantly CD4+CD8+and CD4+CD8-, but in comparison to the phenotype of whole thymocytes, they were enriched in the mature TCRαβhisubset. The binding of thymocytes to TDC at 37℃ was almost completely dependent on Ca2+and Mg2+and partly on an intact cytoskeleton and calmodulin-dependent protein kinase. The adhesion was independent of new protein synthesis and the activities of protein kinases A and C, tyrosine kinases, as well as phosphotyrosine protein phosphatases. The TDC/thymocyte adhesion at 37℃ was partly blocked by anti-LFA-1 (WT.1), anti-CD18 (WT.3), and anti-ICAM-1 (1A29) mAb. MAbs to clas...
Immunology Letters, 1993
We have previously described a type of lymphoepithelial interaction involving CD4 ÷CD8 + thymocytes and a medullary epithelial cell line (E-5). This interaction is mediated by the recently described gp23/45 epithelial adhesion molecule and an as yet unknown thymocyte receptor. The present work describes a thymocyte surface glycoprotein of 16 kDa which binds both to E-5 cells and to the purified gp23/45 adhesion molecule. In addition, a thymic lymphoma cell line (Ti-6), which interacts with the E-5 cells via the gp23/45 receptor, also presents a 16-kDa glycoprotein on its surface. Taken together, the data suggest that the 16-kDa thymocyte surface glycoprotein participates in the binding between these cells and the thymic epithelium.
Immunohistochemical characterization of nurse cells in normal human thymus
Histochemistry, 1991
Lymphoepithelial complexes known as thymic " n u r s e " cells (TNC) have been isolated and described in the thymus of several animal species including man. Most of the investigations on TNC have been carried out in enzymatically digested thymuses in which TNC were isolated by differential sedimentation. In the present study we demonstrate TNC in immunohistochemically stained sections of human thymus as ring-shaped cells completely enclosing thymocytes and localized not only in the cortex, but also at the corticomedullary junction where they have not been previously described. TNC expressed epithelial markers [low and high molecular weight keratins identified by 35/?Hll and 34¢/E12 monoclonal antibodies, a cortical antigen shared with neuroectodermal neoplasms recognized by the GE2 monoclonal antibody, and tissue polypeptide antigen (TPA:B1)], class II histocompatibility antigens (HLA-DR), and thymosin cq. Double staining experiments with the nuclear proliferation-associated antigen Ki-67 and the cortical epithelium marker GE2 showed that most thymocytes enclosed in these cortical TNC were not proliferating. The antigens expressed by TNC indicate that not only cortical, but also medullary epithelial cells are part of the TNC system. The possible role of TNC in the education and maturation of thymocytes is discussed.
RAT THYMOCYTES DIFFERENTIATION IN ADULT THYMUS ORGAN CULTURE
To investigate the differences between thymocytes development in vivo and in vitro, thymus lobe fragments from 12-weeks old male Albino Oxford rats were cultivated over a 7-days period. In the controls and cultivated thymic lobes fragments were evaluated and the viability, apoptosis and cell cycle of thymocytes, as well as the histological characteristics of thymic tissue. Additionally, we analyzed the expression of CD4, CD8 and TCRab on thymocytes by flow cytometry. The obtained results showed that thymus cellularity decreased during cultivated time due to expanded apoptosis, decreased proliferation and the absence of progenitors reseeding thymus. The relative proportion of thymocyte subsets in the first 24 hours of culture remained similar as in the control. However, cultivation for 3 and 7 days modulated the relative proportions between thymoctye subsets. The percentage of DP TCRab low increased, DP TCRab hi subset remained unchanged, both SP TCRab hi subsets decreased while the same mature SP phenotype dominated in culture media. These results demonstrate that cultivated thymic fragments retain the capacity for T cell development, although cultivation modulates this process.