scholarly journals Compartmentalization of Human Thymic Medulla: Facts and Hypotheses

Thymus ◽  
2020 ◽  
Author(s):  
Ildiko Bodi ◽  
Krisztina H.-Minko ◽  
Zsolt Prodan ◽  
Imre Olah
Keyword(s):  
Thymic Medulla

scholarly journals Selective involution of thymic medulla by cyclosporine A with a decrease of mature thymic epithelia, XCR1+ dendritic cells, and epithelium-free areas containing Foxp3+ thymic regulatory T cells

2021 ◽  
Author(s):  
Yasushi Sawanobori ◽  
Yusuke Kitazawa ◽  
Hisashi Ueta ◽  
Kenjiro Matsuno ◽  
Nobuko Tokuda
Keyword(s):  
T Cells ◽  
Dendritic Cells ◽  
Cyclosporine A ◽  
Immunosuppressive Drugs ◽  
Cell System ◽  
Thymic Epithelial Cells ◽  
Complex Molecules ◽  
Single Positive ◽  
Thymic Medulla ◽  
Medullary Thymic Epithelial Cells

AbstractImmunosuppressive drugs such as cyclosporine A (CSA) can disrupt thymic structure and functions, ultimately inducing syngeneic/autologous graft-versus-host disease together with involuted medullas. To elucidate the effects of CSA on the thymus more precisely, we analyzed the effects of CSA on the thymus and T cell system using rats. In addition to confirming the phenomena already reported, we newly found that the proportion of recent thymic emigrants also greatly decreased, suggesting impaired supply. Immunohistologically, the medullary thymic epithelial cells (mTECs) presented with a relative decrease in the subset with a competent phenotype and downregulation of class II major histocompatibility complex molecules. In control rats, thymic dendritic cells (DCs) comprised two subsets, XCR1+SIRP1α−CD4− and XCR1−SIRP1α+CD4+. The former had a tendency to selectively localize in the previously-reported epithelium-containing areas of the rat medullas, and the number was significantly reduced by CSA treatment. The epithelium-free areas, another unique domains in the rat medullas, contained significantly more Foxp3+ thymic Tregs. With CSA treatment, the epithelium-free areas presented strong involution, and the number and distribution of Tregs in the medulla were greatly reduced. These results suggest that CSA inhibits the production of single-positive thymocytes, including Tregs, and disturbs the microenvironment of the thymic medulla, with a decrease of the competent mTECs and disorganization of epithelium-free areas and DC subsets, leading to a generation of autoreactive T cells with selective medullary involution.

scholarly journals A Role for Fas in Negative Selection of Thymocytes In Vivo

1998 ◽  
Vol 187 (9) ◽  
pp. 1427-1438 ◽  
Author(s):  
Hidehiro Kishimoto ◽  
Charles D. Surh ◽  
Jonathan Sprent
Keyword(s):  
Negative Selection ◽  
Cell Receptor ◽  
Staphylococcal Enterotoxin B ◽  
Thymic Medulla ◽  
Enterotoxin B ◽  
High Doses ◽  
Specific Peptide ◽  
Selection Of

To seek information on the role of Fas in negative selection, we examined subsets of thymocytes from normal neonatal mice versus Fas-deficient lpr/lpr mice injected with graded doses of antigen. In normal mice, injection of 1–100 μg of staphylococcal enterotoxin B (SEB) induced clonal elimination of SEB-reactive Vβ8+ cells at the level of the semi-mature population of HSAhi CD4+ 8− cells found in the thymic medulla; deletion of CD4+ 8+ cells was minimal. SEB injection also caused marked elimination of Vβ8+ HSAhi CD4+ 8− thymocytes in lpr/lpr mice. Paradoxically, however, elimination of these cells in lpr/lpr mice was induced by low-to-moderate doses of SEB (≤1 μg) but not by high doses (100 μg). Similar findings applied when T cell receptor transgenic mice were injected with specific peptide. These findings suggest that clonal elimination of semi-mature medullary T cells is Fas independent at low doses of antigen but Fas dependent at high doses. Previous reports documenting that negative selection is not obviously impaired in lpr/lpr mice could thus reflect that the antigens studied were expressed at only a low level.

Cholinesterase activity in quail primary lymphoid organs

Biologia ◽  
2013 ◽  
Vol 68 (6) ◽  
Author(s):  
František Dorko ◽  
Jaroslav Horáček ◽  
Ján Tokarčík ◽  
Michal Miko
Keyword(s):  
Germinal Center ◽  
Cholinesterase Activity ◽  
Histochemical Study ◽  
Nerve Fibers ◽  
Lymphoid Organs ◽  
Bursa Of Fabricius ◽  
Lymphoid Follicles ◽  
Age Dependent ◽  
Close Relationship ◽  
Thymic Medulla

AbstractThe present histochemical study was carried out to analyze the distribution and topography of acetylcholinepositive nerve fibers in the thymus and bursa of Fabricius of quails. The AChE-positive nerve fibers were demonstrated by direct thiocholine histochemical method. Nerve fibers present in the thymuses form periarterial nerve plexuses located mostly in the interlobular septa and on the cortico-medullary junction. Vessels-independent nerve fibers occur also in the parenchyma of thymic medulla, but rarely in parenchyma of the cortex. Within the connective tissue between the bursa of Fabricius and the wall of proctodeum we observed conspicuous AChE-positive ganglia, often in close relationship to greater arteries. Within the wall of bursa of Fabricius, AChE-positive nerve fibers create nerve plexuses around arteries. We observed a close relationship between lymphoid follicules in bursal submucosa and mucosa and AChE-positive nerve fibers. Nerve fibers create a ring around lymphoid follicles, but do not penetrate into the germinal center of the follicle. Arteries inside quail thymuses and bursae of Fabricius contain rich AChE-positive nerve plexuses, when compared to the veins, which have a very poor presence of AChE-positive nerves. According to lesser presence and decreased density of AChE-positive nerve fibers in older animals, we described age-dependent changes in both quail primary lymphoid organs.

P093 Lymphotoxin-alpha produced by autoreactive CD4+ thymocytes controls formation and homeostasis of the thymic medulla

Cytokine ◽  
2012 ◽  
Vol 59 (3) ◽  
pp. 548-549
Author(s):  
M. Irla ◽  
L. Guerri ◽  
J. Guenot ◽  
A. Sergé ◽  
O. Lantz ◽  
...  
Keyword(s):  
Thymic Medulla ◽  
Lymphotoxin Alpha

scholarly journals CCR7 Directs the Migration of Thymocytes into the Thymic Medulla

2004 ◽  
Vol 172 (7) ◽  
pp. 3999-4007 ◽  
Author(s):  
Joanne Kwan ◽  
Nigel Killeen
Keyword(s):  
Thymic Medulla

scholarly journals Myeloid cells activate iNKT cells to produce IL-4 in the thymic medulla

2019 ◽  
Vol 116 (44) ◽  
pp. 22262-22268 ◽  
Author(s):  
Haiguang Wang ◽  
Elise R. Breed ◽  
You Jeong Lee ◽  
Lily J. Qian ◽  
Stephen C. Jameson ◽  
...  
Keyword(s):  
Steady State ◽  
Transgenic Mouse ◽  
Cell Receptor ◽  
Interleukin 4 ◽  
Mouse Strains ◽  
Inkt Cells ◽  
Diphtheria Toxin Receptor ◽  
Toxin Receptor ◽  
Thymic Medulla ◽  
Antigen Presenting

Interleukin-4 (IL-4) is produced by a unique subset of invariant natural killer T (iNKT) cells (NKT2) in the thymus in the steady state, where it conditions CD8+ T cells to become “memory-like” among other effects. However, the signals that cause NKT2 cells to constitutively produce IL-4 remain poorly defined. Using histocytometry, we observed IL-4–producing NKT2 cells localized to the thymic medulla, suggesting that medullary signals might instruct NKT2 cells to produce IL-4. Moreover, NKT2 cells receive and require T cell receptor (TCR) stimulation for continuous IL-4 production in the steady state, since NKT2 cells lost IL-4 production when intrathymically transferred into CD1d-deficient recipients. In bone marrow chimeric recipients, only hematopoietic, not stromal, antigen-presenting cells (APCs), provided such stimulation. Furthermore, using different Cre-recombinase transgenic mouse strains to specifically target CD1d deficiency to various APCs, together with the use of diphtheria toxin receptor (DTR) transgenic mouse strains to deplete various APCs, we found that macrophages were the predominant cell to stimulate NKT2 IL-4 production. Thus, NKT2 cells appear to encounter and require different activating ligands for selection in the cortex and activation in the medulla.

Ultrastructural localisation of NADPH-diaphorase in the chick thymic medulla

1995 ◽  
Vol 279 (2) ◽  
pp. 405-409 ◽  
Author(s):  
Punam Gulati ◽  
An-Soo Chan ◽  
Seng-Kee Leong
Keyword(s):  
Nadph Diaphorase ◽  
Thymic Medulla
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