Aging affects the regeneration of the CD8+ T cell compartment in bone marrow transplanted XXXX .

@entity19 @entity60 @entity3512 @entity1961 @entity58 @entity3844
A chimeric @entity19 model has been used to determine the effect of aging on the differentiation of CD8+ T cells and on the regeneration capacity of the mature peripheral T cell pool after radiation induced depletion. Bone marrow cells from @entity3512 + @entity19 were transplanted into lethally irradiated young or aged @entity19 ( @entity3512 +). After 6 weeks, splenic CD8+ T cells were subjected to phenotypic and functional examinations by flow cytometry. Both young and aged @entity19 were able to develop donor derived ( @entity3512 +) CD8+ T cells. Although the absolute number of T cells was reduced in aged recipients, the ratio of @entity1961 + to CD8+ T cells of donor-origin was the same in young @entity3512 + control @entity19 as it was in both young and aged chimeric @entity19 , indicating that aging has no effect on the ratio of @entity1961 + to CD8+ T cells produced by the thymus. However, the percentage of CD8+ cells in the total @entity3512 + (host-origin) T cell population was significantly higher in young chimeric @entity19 than in age-matched @entity3512 + control @entity19 (P < 0.01), suggesting that a significant over expansion of the @entity3512 + CD8+ subset occurred in young @entity19 during regeneration. The @entity3512 + CD8+ T cells that developed in young hosts were of a naive phenotype with a majority of cells expressing a low level of @entity3844 . In contrast, the majority of those that developed in the aged host displayed a memory phenotype with a high percentage of cells being @entity3844 hi. In addition, the production of @entity58 and @entity60 by @entity3512 + CD8+ T cells was affected by the age of the host. A greater fraction of aged @entity3512 + CD8+ T cells could be induced to produce either @entity60 or @entity58 than young CD8+ T cells. These results suggested that the aged microenvironment has a significant effect on newly developed CD8+ T cells and that the age of the microenvironment also influences the regeneration capacity of CD8+ T cells.
