immunological senescence revealed

Moses Clarke 123moses2clarke9878 at my-deja.com
Sat Jun 10 15:48:20 EST 2000

Moses here: Would it be possible to repopulate the immune system by
means of stem cells derived from their own cord blood collected  sixty
years before hand? Or perhaps a sample of bone marrow could be taken
during youth and then stored til old age of the individual and then
reimplanted to rejuvenate the immune system. Anyway this looks like a
far better bet than having one's body frozen after death!!!

Sincerely Moses Clarke

 In article <8htpr7$ph2$1 at sylvester.vcn.bc.ca>,
  Doug Skrecky <oberon at vcn.bc.ca> wrote:
> Shortage of circulating naive CD8+ T cells provides
> insights on immunodeficiency in aging.
> Blood 95: 2860-2868 2000
> Abstract:
>     Clinical obervations indicate that elderly people are
> prone to severe, often lethal infectious diseases induced
> by novel pathogens. Since the ability to mount primary
> immune responses relies on the availability of naive T
> cells, the circulating naive T-cell reservoir was evaluated
> throughout the human life span. Naive T cells were identified
> as CD95- T lymphocytes for their phenotypic and functional
> features. Indeed, the lack of CD95 marker is sufficient to
> identify a population of naive T cells, as defined by
> coincidence with previously characterized CD45RA+
> CD62L+ T cells. Naive CD95- T cells, as expected,
> require a costimulatory signal, such as CD28, to optimally
> proliferate after anti-CD3 stimulation. Cytofluorimetric
> analysis of circulating T lymphocytes from 120 healthy
> subjects ranging in age from 18 to 105 years revealed
> that naive T cells decreased sharply with age. the
> younger subjects had a naive T-lymphocyte count of
> 177 +-28 cells/microL. Surprisingly, the naive T-cell
> count was lower in CD8+ than in CD4+ subsets at any
> age, and the oldest individuals were almost completely
> depleted of circulating naive CD8+ T cells (13 +-4 cells/microL).
> Concomitantly, a progressive expansion of CD28- T cells
> occurs with age, which can be interpreted as a compensatory
> mechanism. These data provide new insights into age
> related T-cell-mediated immunodeficiency and reveal
> some analogies of T-cell dynamics between advanced
> aging and human immunodeficiency virus (HIV) infection.
> In conclusion, the exhaustion of the naive CD8+ T-cell
> reservoir, which has never been reported before, suggests
> that this T-cell pool is a major target of the aging process
> and may define a parameter possibly related to the life
> span of humans.

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