الأربعاء، 28 مارس 2012

Premature sensence of t- lymphocytes in patients with β -thalassemia



Premature sensence of t- lymphocytes in patients with β -thalassemia

The umbrella term immunosenescence is applied to describe age-associated failing systemic immunity and is believed to contribute to the increased incidence and severity of infectious disease in old animals and people .The immunosenescence is considered as a complex remodeling of lymphocyte subpopulation and function, caused normally by aging in elderly people or prematurely by various chronic inflammatory.







T lymphocytes become specialized in the thymus gland to play a pivotal role in conducting the adaptive immune orchestra resulting in cellular immunity (via CD8 cytotoxic T cells) and B cell-mediated humoral immunity. T cells are considered to be highly vulnerable to the effects of ageing. A number of factors have been linked to the decline in T cell function with age; however, it appears that chronic age-induced thymic atrophy and resultant decreased output of native T cells is the most important factor [2]. 

As somatic cells, the proliferative potential of T cells is restricted. It is not exactly known how many cell cycles a T cell can complete. Because T cells have the ability to upregulate telomerase, they may be able to prolong their life span (Chiu and Harley, 1997; Shiels et al., 1999; Liu et al., 1999; Son et al., 2000). However, after repeated divisions, they enter a program of cellular senescence.
Cellular senescence is characterized by three cardinal features :
(1) altered function, e.g. production of large amounts of inflammatory cytokines.
(2) shortening of telomeric sequences and, eventually, proliferative arrest.
(3) resistance to apoptosis (Campisi, 1996, 2001a,b). 



Dr.Nada Fathy

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