Voie d'immunisation et séquence d'administration de l ... - TEL

tel-00827710, version 1 - 29 May 2013
Although this question remains unclear, this result may be due to a common precursor that
can give rise either to CD8α + DC or CD103 + DC depending on its tissue localization.
4) Heterogeneity of human DCs
While many DC subsets have been described in the context of experimental mouse models,
the same extensive identification and characterization has not yet been possible in humans,
mainly due to the restricted materials available for human study – especially blood. Recently,
a group studying DCs from the thymus identified different DC subsets in this organ
(Vandenabeele et al., 2001). A subset of human DCs expressing Clec9A, similar to the
CD8α + DC subset in the mouse, was identified: it corresponds to BDCA3 + DC subset in the
blood (Crozat et al., 2010; Jongbloed et al., 2010; Poulin et al., 2010). Further investigations
are required to validate that these DCs have the same functional properties as CD8α + mouse
DCs. But further dissection of the different subsets of human DCs will be critical for the
purpose of improving human vaccination (Caminschi et al., 2008).
II. DEVELOPMENT OF A CD8 + T CELL RESPONSE
In a naïve mouse, CD8 + T cells that are specific for a variety of antigens are present. They
become activated upon encounter with APCs presenting the specific cognate antigen. Signals
from the microenvironment are required to mount an efficient T cell response. Upon
activation, T cells expand in order to clear the antigen burden and then the excess specific T
cells die to maintain the homeostasis of the T cell population. Nevertheless, some antigen-
specific T cells will persist as memory T cells (Figure 6).
Figure 6. The different phases of a T cell response
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