The ageing immune system-is it ever too old to become young again

2015-01-13

azim58 - The ageing immune system-is it ever too old to become young again

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The ageing immune system-is it ever too old to become young again

elderly people are particularly susceptible to influenza, with 80–90%
of mortalities from infection with influenza virus occurring in
individuals aged 65 years and older 3.

Elderly individuals also suffer from autoim- munity more frequently,
which further indicates the dysregulation of immune- system function that
can occur with age4.

Although the production of new T cells declines significantly with age,
the thymus still has limited activity even in individuals of almost 100
years of age8.

For example, B cells from aged humans produce antibodies with decreased
affinity for antigen and have an impaired ability to undergo class-switch
recombination com- pared with B cells from younger individu- als16.

the CD8+ T-cell repertoire becomes increasingly skewed towards previously
encountered antigens, particularly those derived from
cytomegalovirus19,20.

B-cell acute lymphoblastic leukaemia is the most common type of
paediatric cancer 27

haematopoietic stem cells (HSCs) from old animals have Nature Reviews |
compared with downregulated expression of genes that control immune-cell
development Immunology HSCs from young animals59. A challenge will be to
identify those genes that act at crucial checkpoints at which multiple
intracellular pathways converge, as these are likely to be the most
promising targets for preventing or reversing immune-cell ageing.

An obvious example is the case of vaccina- tion against influenza virus,
which has an efficacy of only 30–40% in protecting elderly patients
from disease34

caloric restriction both pros and cons here's a pro caloric restriction
increases the number of naive T cells and the diversity of the T-cell
repertoire38,39

here's a con aged mice on a regimen of caloric restriction have increased
mortality in response to influenza virus because they lack the energy
reserves that are required to respond to the infection40

cytokine and hormone treatment

it will be interesting to see if advances in the field of stem-cell
biology will be applicable to immune-system ageing 47

useful to have simple biomarkers with which to accurately measure the
effects of ageing on the immune system. Progress in this area is already
apparent; for example, the loss of CD28 expression by senescent CD8+ T
cells correlates with a decreased response to vaccination52. It is also
interesting that ageing is associated with an increased level of
circulating, pro-inflammatory cytokines, such as Il-6.

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