The Experts below are selected from a list of 5823 Experts worldwide ranked by ideXlab platform
Georg Wick - One of the best experts on this subject based on the ideXlab platform.
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ultrastructural analysis of thymic Nurse Cell epithelium
European Journal of Immunology, 1994Co-Authors: Josef M. Penninger, Hermann Dietrich, Theresa Rieker, Nikolaus Romani, Joerg Klima, Willi Salvenmoser, Hella Stossel, Georg WickAbstract:Thymic Nurse Cells (TNC), a paradigmatic Cell type of cortical epithelium, are large lymphoid-epithelial Cell complexes of thymocytes enclosed within vacuoles lined by the epithelial Cell membrane. TNC express major histocompatibility complex (MHC) class I and class II molecules on their surface and vacuole-lining membranes at high density and it was suggested that TNC provide an optimal microenvironment for positive selection of T Cells. In this report we present electron microscopical data demonstrating that chicken TNC display morphological structures of exocytosis previously shown for hormone-secreting Cells. In TNC, however, exocytosis is restricted to the capillary cleft between the epithelial Cell and engulfed thymocytes. Thus, besides physical contact between the epithelial Cell and enclosed thymocytes, TNC may additionally influence the development of thymocytes through release of soluble factors in a restricted microenvironment. By employing the 3-(2,4-dinitroanilino)-3'-amino-N-methyl-propylamine technique which at the ultrastructural level detects acidic organelles involved in processing of antigens presented by MHC class II molecules, we also show that TNC contain acidic compartments similar to classical antigen-presenting Cells, i.e. early and late endosomes and lysosomes, albeit in a lower amount than in thymic dendritic Cells. This fact provides evidence that TNC not only are capable of antigen presentation but also possess the intraCellular machinery for antigen processing.
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thymic Nurse Cell lymphocytes react against self major histocompatibility complex
European Journal of Immunology, 1992Co-Authors: Josef M. Penninger, Georg WickAbstract:It has been postulated that thymic Nurse Cells (TNC), lymphoid-epithelial complexes composed of thymocytes enclosed within major histocompatibility complex (MHC) class I+ and class II+ cortical epithelial Cells, may provide an optimal microenvironment for the process of T Cell selection. By transplanting single TNC in the avian chorionallantoic membrane assay we demonstrate that a significant portion of intra-TNC lymphocytes (TNC-L) possess reactivity against self-MHC molecules. The frequency of these autoreactive Cells among TNC-L exceeds by far that of thymocytes or peripheral blood lymphocytes of the same donor. These results indicate that TNC-L constitute a T Cell population enriched for self-MHC reactivity, i.e. Cells that have undergone positive selection, but not yet deletion and/or deactivation.
Jerry C. Guyden - One of the best experts on this subject based on the ideXlab platform.
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thymic Nurse Cell multiCellular complexes in hy tcr transgenic mice demonstrate their association with mhc restriction
Experimental Biology and Medicine, 2007Co-Authors: Marcia Martinez, Mark Pezzano, Michael Samms, Tonya M Hendrix, Oluwaseun Adeosun, Jerry C. GuydenAbstract:This study examines thymic Nurse Cell (TNC) function during T-Cell development. It has been suggested that TNCs function in the removal of nonfunctional and/or apoptotic thymocytes and do not participate in major histocompatibility complex restriction. We analyzed TNCs isolated from both normal C57BL/6 mice and C57BL/6 TgN (TCRHY) mice (HY-TCR transgenic mice). Using confocal microscopic analyses of TNCs isolated from C57BL/6 animals, we showed that 75%–78% of the enclosed thymocyte subset was viable, and 87%–90% of these Cells expressed both CD4 and CD8. CD4 and CD8 also were expressed on TNC thymocytes isolated from both male and female HY-TCR transgenic mice. The transgenic female thymus was shown to have 17 times more TNCs per milligram of thymus than the transgenic male thymus. TNCs from HY-TCR transgenic females were 8–10 μm larger than transgenic male TNCs, and the female TNCs contained five times more thymocytes within intracytoplasmic vacuoles, with less than 4% apoptosis. However, more than 42% ...
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Questionable Thymic Nurse Cell
Microbiology and molecular biology reviews : MMBR, 2001Co-Authors: Mark Pezzano, Michael Samms, Marcia Martinez, Jerry C. GuydenAbstract:Since their discovery in 1980, thymic Nurse Cells (TNCs) have been controversial. Questions pertaining to the existence of the TNC as a “unit” Cell with thymocytes completely enclosed within its cytoplasm were the focus of initial debates. Early skeptics proposed the multiCellular complex to be an artifact of the procedures used to isolate TNCs from the thymus. Since that time, TNCs have been found in fish, frogs, tadpoles, chickens, sheep, pigs, rats, mice, and humans. Their evolutionary conservation throughout the animal kingdom relieved most speculations about the existence of TNCs and at the same time demonstrated their apparent importance to the thymus and T-Cell development. In this review we will discuss and debate reports that describe (i) the organization or structure of TNCs, (ii) the thymocyte subset(s) found within the cytoplasm of TNCs and their uptake and release, and (iii) the function of this fascinating multiCellular interaction that occurs during the process of T-Cell development. Discussions about the future of the field and experimental approaches that will lead to answers to remaining questions are also presented.
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A thymic Nurse Cell-specific monoclonal antibody.
Cellular Immunology, 1998Co-Authors: Mark Pezzano, Karen D. King, Deborah Philp, Adebowale Adeyemi, Birdette Gardiner, Jun Yang, Michael Samms, William Boto, Jerry C. GuydenAbstract:Abstract A thymic epithelial Cell line (tsTNC-1) that maintains the ability to selectively bind and internalize immature αβTCRloCD4+CD8+thymocytesin vitrowas used in the development of a monoclonal antibody that is specific to the Cell surface of thymic Nurse Cells (TNCs) in the thymus. The rat monoclonal antibody ph91 showed specificity to Cells of the subcapsular region of the thymic cortex. Upon mechanical dispersion of the thymusin vitro, ph91 recognized Cells displaying the multiCellular morphology unique to TNCs. Ph91 staining was not detected on fresh thymocytes, stromal Cells of the inner thymic cortex, thymic medullary Cells, B Cells or fibroblasts. Ph91 recognized a 43-kDa protein on the surface of TNCs. Exposure of tsTNC-1 Cells to ph91 in tissue culture significantly reduced the percentage of binding of the αβTCRloCD4+CD8+thymocyte subset previously shown to target TNCs. In organ culture, ph91 reduced the viability of developing thymocytes by 70%. The largest reduction was found in the αβTCR+CD4+CD8+thymocyte subset. These results represent the first report of a TNC-specific monoclonal antibody. Further, the antigen to which ph91 binds may play a role in the process of thymocyte binding and their subsequent internalization which is unique to TNCs and important to the T Cell developmental process.
Josef M. Penninger - One of the best experts on this subject based on the ideXlab platform.
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ultrastructural analysis of thymic Nurse Cell epithelium
European Journal of Immunology, 1994Co-Authors: Josef M. Penninger, Hermann Dietrich, Theresa Rieker, Nikolaus Romani, Joerg Klima, Willi Salvenmoser, Hella Stossel, Georg WickAbstract:Thymic Nurse Cells (TNC), a paradigmatic Cell type of cortical epithelium, are large lymphoid-epithelial Cell complexes of thymocytes enclosed within vacuoles lined by the epithelial Cell membrane. TNC express major histocompatibility complex (MHC) class I and class II molecules on their surface and vacuole-lining membranes at high density and it was suggested that TNC provide an optimal microenvironment for positive selection of T Cells. In this report we present electron microscopical data demonstrating that chicken TNC display morphological structures of exocytosis previously shown for hormone-secreting Cells. In TNC, however, exocytosis is restricted to the capillary cleft between the epithelial Cell and engulfed thymocytes. Thus, besides physical contact between the epithelial Cell and enclosed thymocytes, TNC may additionally influence the development of thymocytes through release of soluble factors in a restricted microenvironment. By employing the 3-(2,4-dinitroanilino)-3'-amino-N-methyl-propylamine technique which at the ultrastructural level detects acidic organelles involved in processing of antigens presented by MHC class II molecules, we also show that TNC contain acidic compartments similar to classical antigen-presenting Cells, i.e. early and late endosomes and lysosomes, albeit in a lower amount than in thymic dendritic Cells. This fact provides evidence that TNC not only are capable of antigen presentation but also possess the intraCellular machinery for antigen processing.
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thymic Nurse Cell lymphocytes react against self major histocompatibility complex
European Journal of Immunology, 1992Co-Authors: Josef M. Penninger, Georg WickAbstract:It has been postulated that thymic Nurse Cells (TNC), lymphoid-epithelial complexes composed of thymocytes enclosed within major histocompatibility complex (MHC) class I+ and class II+ cortical epithelial Cells, may provide an optimal microenvironment for the process of T Cell selection. By transplanting single TNC in the avian chorionallantoic membrane assay we demonstrate that a significant portion of intra-TNC lymphocytes (TNC-L) possess reactivity against self-MHC molecules. The frequency of these autoreactive Cells among TNC-L exceeds by far that of thymocytes or peripheral blood lymphocytes of the same donor. These results indicate that TNC-L constitute a T Cell population enriched for self-MHC reactivity, i.e. Cells that have undergone positive selection, but not yet deletion and/or deactivation.
Mark Pezzano - One of the best experts on this subject based on the ideXlab platform.
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thymic Nurse Cell multiCellular complexes in hy tcr transgenic mice demonstrate their association with mhc restriction
Experimental Biology and Medicine, 2007Co-Authors: Marcia Martinez, Mark Pezzano, Michael Samms, Tonya M Hendrix, Oluwaseun Adeosun, Jerry C. GuydenAbstract:This study examines thymic Nurse Cell (TNC) function during T-Cell development. It has been suggested that TNCs function in the removal of nonfunctional and/or apoptotic thymocytes and do not participate in major histocompatibility complex restriction. We analyzed TNCs isolated from both normal C57BL/6 mice and C57BL/6 TgN (TCRHY) mice (HY-TCR transgenic mice). Using confocal microscopic analyses of TNCs isolated from C57BL/6 animals, we showed that 75%–78% of the enclosed thymocyte subset was viable, and 87%–90% of these Cells expressed both CD4 and CD8. CD4 and CD8 also were expressed on TNC thymocytes isolated from both male and female HY-TCR transgenic mice. The transgenic female thymus was shown to have 17 times more TNCs per milligram of thymus than the transgenic male thymus. TNCs from HY-TCR transgenic females were 8–10 μm larger than transgenic male TNCs, and the female TNCs contained five times more thymocytes within intracytoplasmic vacuoles, with less than 4% apoptosis. However, more than 42% ...
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Questionable Thymic Nurse Cell
Microbiology and molecular biology reviews : MMBR, 2001Co-Authors: Mark Pezzano, Michael Samms, Marcia Martinez, Jerry C. GuydenAbstract:Since their discovery in 1980, thymic Nurse Cells (TNCs) have been controversial. Questions pertaining to the existence of the TNC as a “unit” Cell with thymocytes completely enclosed within its cytoplasm were the focus of initial debates. Early skeptics proposed the multiCellular complex to be an artifact of the procedures used to isolate TNCs from the thymus. Since that time, TNCs have been found in fish, frogs, tadpoles, chickens, sheep, pigs, rats, mice, and humans. Their evolutionary conservation throughout the animal kingdom relieved most speculations about the existence of TNCs and at the same time demonstrated their apparent importance to the thymus and T-Cell development. In this review we will discuss and debate reports that describe (i) the organization or structure of TNCs, (ii) the thymocyte subset(s) found within the cytoplasm of TNCs and their uptake and release, and (iii) the function of this fascinating multiCellular interaction that occurs during the process of T-Cell development. Discussions about the future of the field and experimental approaches that will lead to answers to remaining questions are also presented.
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A thymic Nurse Cell-specific monoclonal antibody.
Cellular Immunology, 1998Co-Authors: Mark Pezzano, Karen D. King, Deborah Philp, Adebowale Adeyemi, Birdette Gardiner, Jun Yang, Michael Samms, William Boto, Jerry C. GuydenAbstract:Abstract A thymic epithelial Cell line (tsTNC-1) that maintains the ability to selectively bind and internalize immature αβTCRloCD4+CD8+thymocytesin vitrowas used in the development of a monoclonal antibody that is specific to the Cell surface of thymic Nurse Cells (TNCs) in the thymus. The rat monoclonal antibody ph91 showed specificity to Cells of the subcapsular region of the thymic cortex. Upon mechanical dispersion of the thymusin vitro, ph91 recognized Cells displaying the multiCellular morphology unique to TNCs. Ph91 staining was not detected on fresh thymocytes, stromal Cells of the inner thymic cortex, thymic medullary Cells, B Cells or fibroblasts. Ph91 recognized a 43-kDa protein on the surface of TNCs. Exposure of tsTNC-1 Cells to ph91 in tissue culture significantly reduced the percentage of binding of the αβTCRloCD4+CD8+thymocyte subset previously shown to target TNCs. In organ culture, ph91 reduced the viability of developing thymocytes by 70%. The largest reduction was found in the αβTCR+CD4+CD8+thymocyte subset. These results represent the first report of a TNC-specific monoclonal antibody. Further, the antigen to which ph91 binds may play a role in the process of thymocyte binding and their subsequent internalization which is unique to TNCs and important to the T Cell developmental process.
Michael Samms - One of the best experts on this subject based on the ideXlab platform.
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thymic Nurse Cell multiCellular complexes in hy tcr transgenic mice demonstrate their association with mhc restriction
Experimental Biology and Medicine, 2007Co-Authors: Marcia Martinez, Mark Pezzano, Michael Samms, Tonya M Hendrix, Oluwaseun Adeosun, Jerry C. GuydenAbstract:This study examines thymic Nurse Cell (TNC) function during T-Cell development. It has been suggested that TNCs function in the removal of nonfunctional and/or apoptotic thymocytes and do not participate in major histocompatibility complex restriction. We analyzed TNCs isolated from both normal C57BL/6 mice and C57BL/6 TgN (TCRHY) mice (HY-TCR transgenic mice). Using confocal microscopic analyses of TNCs isolated from C57BL/6 animals, we showed that 75%–78% of the enclosed thymocyte subset was viable, and 87%–90% of these Cells expressed both CD4 and CD8. CD4 and CD8 also were expressed on TNC thymocytes isolated from both male and female HY-TCR transgenic mice. The transgenic female thymus was shown to have 17 times more TNCs per milligram of thymus than the transgenic male thymus. TNCs from HY-TCR transgenic females were 8–10 μm larger than transgenic male TNCs, and the female TNCs contained five times more thymocytes within intracytoplasmic vacuoles, with less than 4% apoptosis. However, more than 42% ...
-
Questionable Thymic Nurse Cell
Microbiology and molecular biology reviews : MMBR, 2001Co-Authors: Mark Pezzano, Michael Samms, Marcia Martinez, Jerry C. GuydenAbstract:Since their discovery in 1980, thymic Nurse Cells (TNCs) have been controversial. Questions pertaining to the existence of the TNC as a “unit” Cell with thymocytes completely enclosed within its cytoplasm were the focus of initial debates. Early skeptics proposed the multiCellular complex to be an artifact of the procedures used to isolate TNCs from the thymus. Since that time, TNCs have been found in fish, frogs, tadpoles, chickens, sheep, pigs, rats, mice, and humans. Their evolutionary conservation throughout the animal kingdom relieved most speculations about the existence of TNCs and at the same time demonstrated their apparent importance to the thymus and T-Cell development. In this review we will discuss and debate reports that describe (i) the organization or structure of TNCs, (ii) the thymocyte subset(s) found within the cytoplasm of TNCs and their uptake and release, and (iii) the function of this fascinating multiCellular interaction that occurs during the process of T-Cell development. Discussions about the future of the field and experimental approaches that will lead to answers to remaining questions are also presented.
-
A thymic Nurse Cell-specific monoclonal antibody.
Cellular Immunology, 1998Co-Authors: Mark Pezzano, Karen D. King, Deborah Philp, Adebowale Adeyemi, Birdette Gardiner, Jun Yang, Michael Samms, William Boto, Jerry C. GuydenAbstract:Abstract A thymic epithelial Cell line (tsTNC-1) that maintains the ability to selectively bind and internalize immature αβTCRloCD4+CD8+thymocytesin vitrowas used in the development of a monoclonal antibody that is specific to the Cell surface of thymic Nurse Cells (TNCs) in the thymus. The rat monoclonal antibody ph91 showed specificity to Cells of the subcapsular region of the thymic cortex. Upon mechanical dispersion of the thymusin vitro, ph91 recognized Cells displaying the multiCellular morphology unique to TNCs. Ph91 staining was not detected on fresh thymocytes, stromal Cells of the inner thymic cortex, thymic medullary Cells, B Cells or fibroblasts. Ph91 recognized a 43-kDa protein on the surface of TNCs. Exposure of tsTNC-1 Cells to ph91 in tissue culture significantly reduced the percentage of binding of the αβTCRloCD4+CD8+thymocyte subset previously shown to target TNCs. In organ culture, ph91 reduced the viability of developing thymocytes by 70%. The largest reduction was found in the αβTCR+CD4+CD8+thymocyte subset. These results represent the first report of a TNC-specific monoclonal antibody. Further, the antigen to which ph91 binds may play a role in the process of thymocyte binding and their subsequent internalization which is unique to TNCs and important to the T Cell developmental process.
