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

tel-00827710, version 1 - 29 May 2013
priming: in vitro versus in vivo study, the antigenic model used, the role of NK cells, the
removal of DCs via CD11c-DTR mice treated with diphteria toxin versus the inhibition
blocking of antigen presentation with blocking antibodies. Each of these approaches modulate
antigen persistence, but at a different level, and may also impact other aspects of immune
response at the same time.
Our model would clearly benefit from further understanding regarding how H-2K bm1 mOva
cells are killed after injection, as this would allow us to better control persistence of antigen
and, as a result, understand whether persistence of live cell-associated antigen is a crucial
parameter for the robustness of the response.
In parallel, the use of splenocytes expressing the receptor for the diphteria toxin as the cell-
associated antigen may help us to address this question. It would permit the removal of
antigen at different time points post-immunization by injecting diphteria toxin and investigate
the quality of the subsequent response in these differing conditions. The aim here would be to
block antigen persistence upon i.d. immunization and observe whether we obtain a response
similar to what we observed after i.v. immunization. This idea was the aim of our experiments
using the K b -SIINFEKL antibody to block antigen presentation. The opposite approach could
also be investigated and would involve mimicking antigen persistence after i.v. immunization
(by several successive antigen injections for instance) and examine whether we are able to
improve the quality of the resulting T cell response.
4) A role for CD4 help?
CD4 help has been shown crucial for the initiation of a completely functional CD8 + T cell
response (Bennett et al., 1997), especially for effective cross-priming. However it has been
demonstrated in a tumor model that CD4 help may or may not be required depending on the
route of immunization. Bour and colleagues compared i.d. and i.p. injection of tumor cells
and observed that an anti-tumor CD8 + T cell response developed without CD4 + help after i.d.
immunization, whereas help was required after i.p. immunization (Bour et al., 1998). We
investigated the necessity of CD4 + help using a variety of different approaches in our model:
in particular we transferred low numbers of TCR-transgenic specific OT-II CD4 + T cells. We
also tried to stain endogenous antigen-specific CD4+ T cells using MHC-II-peptide tetramers.
However, we were not able to detect specific cells in a reproducible way. The role of these
cells need to be further investigated.
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