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Background
Homeostatic mechanisms to maintain the T cell compartment diversity indicate an ongoing process of thymic activity and peripheral T cell renewal during human life. These processes are expected to be accelerated after childhood thymectomy and by the influence of cytomegalovirus (CMV) inducing a prematurely aged immune system.
The study aimed to investigate proportional changes and replicative history of CD8+ T cells, of recent thymic emigrants (RTEs) and CD103+ T cells (mostly gut-experienced) and the role of Interleukin-(IL)-7 and IL-7 receptor (CD127)-expressing T cells in thymectomized patients compared to young and old healthy controls.
Results
Decreased proportions of naive and CD31 + CD8+ T cells were demonstrated after thymectomy, with higher proliferative activity of CD127-expressing T cells and significantly shorter relative telomere lengths (RTLs) and lower T cell receptor excision circles (TRECs). Increased circulating CD103+ T cells and a skewed T cell receptor (TCR) repertoire were found after thymectomy similar to elderly persons. Naive T cells were influenced by age at thymectomy and further decreased by CMV.
Conclusions
After childhood thymectomy, the immune system demonstrated constant efforts of the peripheral CD8+ T cell compartment to maintain homeostasis. Supposedly it tries to fill the void of RTEs by peripheral T cell proliferation, by at least partly IL-7-mediated mechanisms and by proportional increase of circulating CD103+ T cells, reminiscent of immune aging in elderly. Although other findings were less significant compared to healthy elderly, early thymectomy demonstrated immunological alterations of CD8+ T cells which mimic features of premature immunosenescence in humans.
Virale Reaktivierungen treten im Rahmen der Immundefizienz und Immunsuppression nach allogener Stammzelltransplantation häufig auf und können zu schwerwiegenden Komplikationen führen. Ziel dieser retrospektiven Studie war die Charakterisierung von viralen Reaktivierungen im ersten Jahr nach allogener Stammzelltransplantation, die Identifikation von Risikofaktoren sowie die Untersuchung des Einflusses viraler Reaktivierungen auf das Transplantationsoutcome. 107 pädiatrische allogene Stammzelltransplantationen im Zeitrahmen von Januar 2005 bis Dezember 2015 wurden in diesem Zusammenhang auf Infektionen mit dem Epstein-Barr Virus (EBV), Cytomegalovirus (CMV), Humanen Herpesvirus 6 (HHV 6), Herpes simplex Virus (HSV), Varicella zoster Virus (VZV) und Adenovirus (ADV) untersucht.