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|Title:||Characterization of CD8+ T-CELL populations of the human peripheral blood|
|Author:||Monteiro, Marta Ferreira, 1978-|
Teses de doutoramento (Registo) - 2009
|Abstract:||Following antigenic challenge, naïve CD8+ T lymphocytes undergo severalchanges, including the expression of cell-surface molecules. In humans, theassociation of CCR7, CD45RA, CD27 and CD28 is widely used to discriminate areproducible set of functionally different subpopulations of CD8+ T cells. However,the prevailing data concerning the description of these subsets remainsfragmentary, since a multitude of studies used a different and limited set of surfacemarkers. Hence, some CD8+ T-cell subsets are still not clearly established,especially within the CCR7 CD45RA+ and CCR7 CD45R0+ compartments, andthe correspondent differential roles and lineage relationships remain undisclosed.The present study aims to define a predictable and precise correlationbetween particular cell surface markers and CD8+ T-cell functional properties. Weassociated CCR7, CD45RA, CD27 and CD28 expression levels to subdivide CD8+T cells into fourteen different cell types. These populations were further isolatedand gene expression of 18 genes was assessed, simultaneously, in single-cells bya novel multiplex RT-PCR method we developed. Our results demonstrate that thedifferent subpopulations display distinct and characteristic gene co-expressionpatterns, reproducible between donors. CD45RA expression is required to definethe naïve subset, but does not discriminate functionally different populations ofprimed cells. In contrast, gene expression profiles of CCR7-CD8+ T cells correlatesignificantly to CD27 expression levels and CD27/CD28 co-expression, and ahierarchy of activation stages could be established as follows: naïve < CD27high <CD27+CD28+ < CD28+CD27 < CD27+CD28 < CD27 CD28 . Surprisingly, wefound that CD45RA+ and CD45RA cells of each of these subsets had the samegene expression patterns at both qualitative and quantitative level. Importantly, weidentified minor subsets displaying characteristics of recent activation that could befound in both CD45RA+ and CD45RA compartments. These findings stronglysuggest that differentiation of naïve CD8+ T cells into effectors does notnecessarily imply CD45RA downregulation. Furthermore, they describe novelCD8+ T cell subsets and establish a correlation between surface phenotype andcell function, which helped to identify homogeneous populations.|
|Description:||Tese de doutoramento (Registo), Univ. de Lisboa, nº 28, 2009, (Immunologie), Université René Descartes - Paris V, 2009|
|Appears in Collections:||REIT - Teses de Doutoramento (Registos)|
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