scholarly journals THYMUS CELL MIGRATION

1967 ◽  
Vol 126 (2) ◽  
pp. 291-304 ◽  
Author(s):  
Irving L. Weissman

The preceding studies have established the following points: Intrathymic labeling of thymic lymphocytes provides an adequate marker system to detect the migration of thymus cells to peripheral lymphoid sites. In the newborn, this comprises a major portion of the total lymphocyte population in lymph nodes and spleen. In the adult, this migration is limited to specific portions of lymph nodes and spleen, i.e., those portions which serve the recirculating pool of small lymphocytes. Kinetic studies of labeling within the adult thymus indicate that large cells give rise to medium and small cells, which then migrate to the specific sites noted above. In the newborn, the kinetic pattern is similar to that of adults, with the single distinction that large cells also migrate, accelerating the tempo of migration in these hosts. The long-term fate and function of thymus cell migrants has not yet been determined.

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Mladen Jergović ◽  
Christopher P. Coplen ◽  
Jennifer L. Uhrlaub ◽  
David G. Besselsen ◽  
Shu Cheng ◽  
...  

AbstractNaïve T (Tn) cells require two homeostatic signals for long-term survival: tonic T cell receptor:self-peptide–MHC contact and IL-7 stimulation. However, how microbial exposure impacts Tn homeostasis is still unclear. Here we show that infections can lead to the expansion of a subpopulation of long-lived, Ly6C+ CD8+ Tn cells with accelerated effector function. Mechanistically, mono-infection with West Nile virus transiently, and polymicrobial exposure persistently, enhances Ly6C expression selectively on CD5hiCD8+ cells, which in the case of polyinfection translates into a numerical CD8+ Tn cell increase in the lymph nodes. This conversion and expansion of Ly6C+ Tn cells depends on IFN-I, which upregulates MHC class I expression and enhances tonic TCR signaling in differentiating Tn cells. Moreover, for Ly6C+CD8+ Tn cells, IFN-I-mediated signals optimize their homing to secondary sites, extend their lifespan, and enhance their effector differentiation and antibacterial function, particularly for low-affinity clones. Our results thus uncover significant regulation of Tn homeostasis and function via infection-driven IFN-I, with potential implications for immunotherapy.


1978 ◽  
Vol 147 (1) ◽  
pp. 196-206 ◽  
Author(s):  
D H Sherr ◽  
M R Szewczuk ◽  
G W Siskind

Lethally irradiated mice reconstituted with adult thymus cells and neonatal or fetal liver cells produce an anti-2,4-dinitrophenyl or anti-bovine gamma globulin response of restricted heterogeneity of affinity in comparison with the response of mice reconstituted with B cells from adult donors. In addition, mice reconstituted with day 15 fetal B cells and adult thymus cells produce relatively few indirect plaque-forming cells (PFC). It was found that B cells acquire the capacity to produce a heterogeneous response, of predominantly indirect PFC within 7 days of transfer only when thymus cells are transferred along with the B cells. B cells from fetal or neonatal donors transferred without young adult thymus cells develop the capacity to generate indirect PFC within 13 days after transfer to adult recipients, but continue to produce a response of restricted heterogeneity of affinity for up to 28 days after transfer. Thus, it has been shown that cells present in the thymus facilitate, or are necessary for the functional maturation of B lymphocytes. Furthermore, the data suggest that maturation of the B-cell population to produce a heterogeneous response is controlled independently of its maturation to be capable of producing indirect PFC.


Author(s):  
Nataliya G. Grushka ◽  
Svitlana I. Pavlovych ◽  
Tetyana M. Bryzgina ◽  
Vera S. Sukhina ◽  
Nataliya V. Makogon ◽  
...  

Author(s):  
Robert Stojanov ◽  
Sarah Rosengaertner ◽  
Alex de Sherbinin ◽  
Raphael Nawrotzki

AbstractDevelopment cooperation actors have been addressing climate change as a cross-cutting issue and investing in climate adaptation projects since the early 2000s. More recently, as concern has risen about the potential impacts of climate variability and change on human mobility, development cooperation actors have begun to design projects that intentionally address the drivers of migration, including climate impacts on livelihoods. However, to date, we know little about the development cooperation’s role and function in responding to climate related mobility and migration. As such, the main aim of this paper is to outline the policy frameworks and approaches shaping development cooperation actors’ engagement and to identify areas for further exploration and investment. First, we frame the concept of climate mobility and migration and discuss some applicable policy frameworks that govern the issue from various perspectives; secondly, we review the toolbox of approaches that development cooperation actors bring to climate mobility; and third, we discuss the implications of the current Covid-19 pandemic and identify avenues for the way forward. We conclude that ensuring safe and orderly mobility and the decent reception and long-term inclusion of migrants and displaced persons under conditions of more severe climate hazards, and in the context of rising nationalism and xenophobia, poses significant challenges. Integrated approaches across multiple policy sectors and levels of governance are needed. In addition to resources, development cooperation actors can bring data to help empower the most affected communities and regions and leverage their convening power to foster more coordinated approaches within and across countries.


2020 ◽  
Vol 4 (Supplement_1) ◽  
Author(s):  
Rajiv Ark

Abstract Case report - Introduction In 2011 a gentleman in his 50s presented with nasal blockage and bloody discharge. He was diagnosed with sarcoidosis and after 9 years of failed strategies to control his disease, he developed dactylitis. X-ray of the hands showed severe arthropathy in the distal interphalangeal joints. This case demonstrates an uncommon extrapulmonary manifestation of sarcoidosis. Although most of his follow up was with a respiratory clinic, his main symptoms were not due to interstitial lung disease, highlighting the importance of a multidisciplinary approach. To reduce the need for steroids, several DMARDs were tried illustrating that there are limited treatment options. Case report - Case description This gentleman presented in June 2011 with left epiphora, bloody nasal discharge and fatigue. He had no family history of sarcoidosis and was of Caucasian ethnicity. He was referred by his GP to Ophthalmology and ENT. Septoplasty showed a 95% blockage at the lacrimal sac. A biopsy was performed, and histology showed a nasal sarcoid granuloma. He was referred to the respiratory team who requested a high-resolution CT scan showing sizeable lymph nodes. One inguinal node was biopsied confirming sarcoid granulomas before starting treatment. Calcium was briefly raised, and serum ACE was initially 123. He was started on 40mg of prednisolone for 6 weeks, which was tapered to 20/25mg on alternating days. There was a recurrence of his nasal discharge; steroids were increased again but he developed symptoms of muscle weakness from long term steroid use. He was referred to an interstitial lung disease clinic at a tertiary centre where he was investigated for cardiac sarcoidosis with MRI due to ventricular ectopics. Hydroxychloroquine was started to reduce the steroid use however he developed symptoms of tinnitus, so it was stopped. Methotrexate, Azathioprine and Leflunomide were all trialled to however they did not have any impact on controlling his disease. His Prednisolone was slowly reduced by 1mg a month. When he had recurrence of his symptoms, he was given IV methylprednisolone. Nine years after his first presentation he presented with stiffness of the right thumb base. This progressed to dactylitis and slight fixed flexion deformity of right index finger and left little finger. An x-ray of his hands showed disease in the distal interphalangeal joints bilaterally with severe changes in the left little finger. The effects of long-term steroids led him to request a letter to support early retirement. Case report - Discussion The main rationale for changing treatment options was to reduce the prednisolone dose. Steroids were the only treatment option that showed evidence of controlling his disease when the dose was between 25mg and 40mg a day. Each of the DMARDs that were trialled had a different side effect profile and did not show any evidence of suppressing disease as symptoms recurred. Dose changes later in treatment fluctuated, reflecting a balancing act between disease recurrence and side effects of long-term steroids. There are many extra pulmonary manifestations of sarcoidosis that were investigated in this case. The first being the nasal granuloma, which can occur in sarcoid patients with symptoms of epistaxis, crusting, congestion, and pain. There were granulomatous changes seen in the hila as well as other lymph nodes such as the inguinal region; inguinal lymphadenopathy can lead to pain in the groin area. In addition to this it was important to exclude uveitis with ophthalmology review as he had symptoms of epiphora. Uveitis can be diagnosed in ophthalmological assessment of sarcoid patients in the absence of ocular complaints. Cardiac sarcoidosis was excluded with an MRI at a specialist heart and lung centre due to ventricular ectopics. Cardiac sarcoidosis can lead to heart block, arrhythmias, and congestive cardiac failure. Finally, he developed sarcoid arthropathy, review of his radiological images over time showed extensive damage to the joints of the hand. This gentleman had poor outcomes due to limited treatment options for his disease. Being restricted to long term steroid as the mainstay of treatment led to early retirement due to fatigue and muscle weakness. Conversely, under dosing steroids led to recurrence in symptoms. His disease is still not controlled as shown by an evolving sarcoid arthropathy. Case report - Key learning points An illustration of sarcoid arthropathy is also shown in this case. Sarcoid arthropathy is an uncommon manifestation of the disease primarily affecting joints in the hands and feet. In this case the distal interphalangeal joints and proximal interphalangeal joints were affected. The first symptom of arthropathy was stiffness of the base of the right thumb in 2017, this could fit with an osteoarthritic picture and could be mistaken for it in undiagnosed sarcoidosis. The most severe disease was in the DIP of the left little finger, which is not commonly affected. An oligoarthritic pattern with involvement of the ankle is seen more often. This is also an unusual case of sarcoidosis as there was no family history of the disease and his ethnicity did not predispose him to the condition. He also had a few uncommon extra pulmonary manifestations of sarcoidosis. The importance of a multidisciplinary approach in managing sarcoidosis was demonstrated in this case. Most of his follow up was with a respiratory clinic. However, respiratory symptoms were not the main issue during the patient journey; early ENT and rheumatology input was significant in managing his disease. Although pulmonary lymph nodes were enlarged, they did not affect his lung function.


Cells ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 63
Author(s):  
Ji Hye Kwon ◽  
Miyeon Kim ◽  
Soyoun Um ◽  
Hyang Ju Lee ◽  
Yun Kyung Bae ◽  
...  

In order to provide a sufficient number of cells for clinical use, mesenchymal stem cells (MSCs) must be cultured for long-term expansion, which inevitably triggers cellular senescence. Although the small size of MSCs is known as a critical determinant of their fate, the main regulators of stem cell senescence and the underlying signaling have not been addressed. Umbilical cord blood-derived MSCs (UCB-MSCs) were obtained using size-isolation methods and then cultured with control or small cells to investigate the major factors that modulate MSC senescence. Cytokine array data suggested that the secretion of interukin-8 (IL-8) or growth-regulated oncogene-alpha (GROa) by senescent cells was markedly inhibited during incubation of small cells along with suppression of cognate receptor (C-X-C motif chemokine receptor2, CXCR2) via blockade of the autocrine/paracrine positive loop. Moreover, signaling via toll-like receptor 2 (TLR2) and TLR5, both pattern recognition receptors, drove cellular senescence of MSCs, but was inhibited in small cells. The activation of TLRs (2 and 5) through ligand treatment induced a senescent phenotype in small cells. Collectively, our data suggest that small cell from UCB-MSCs exhibit delayed cellular senescence by inhibiting the process of TLR signaling-mediated senescence-associated secretory phenotype (SASP) activation.


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