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

tel-00827710, version 1 - 29 May 2013
Figure 46. Enhancement of cross-priming upon late poly I:C delivery is type I IFN-dependent.
WT, IFNAR -/- and IRF3/7DKO mice were immunized i.d. with 5x10 5 K bm1 mOva splenocytes. Three
days later, 100µg of poly I:C was administered. On day 10, the spleen and the draining lymph node
were harvested and pooled. CD8 + T cells were purified to perform an IFNγ-Elispot. SFC, Spot
forming cell.
2) Late type I IFN enhance cross-priming at the level of antigen uptake
and/or presentation
As we observed that type I IFN are responsible for the enhancement of the response, we were
interested in dissecting the mechanisms of this phenomenon and, in particular, determining
the targets of these cytokines. CD45.1/2 WT and CD45.2/2 IFNAR -/- OT-I were transferred
into CD45.1/1 WT recipients. These mice were then immunized with K bm1 mOva splenocytes
and injected with poly I:C three days later. Seven days post-immunization, OT-I cells were
enriched with an anti-CD45.2 antibody for further characterization (Figure 47A). We
observed that the percentage of IFNγ-producing cells increased upon poly I:C treatment in
WT as well as in IFNAR -/- OT-I populations (Figure 47B). Similar increases in expression
were obtained by comparing the MFI of the IFNγ signal in the two populations (Figure 47C).
Of note, IL-2 and TNFα production by these cells was also evaluated (data not shown). No
clear differences were observed for these cytokines either - the cells producing the highest
amount of IFNγ were able to secrete IL-2 and TNFα. From these data, we concluded that type
I IFN act at the level of antigen uptake and/or presentation. However we also observed that
the basal levels and the magnitude of the increase was not the same between WT and IFNAR -
/- populations. Consequently, it is possible that these differences could be explained by the
direct action of type I IFN on T cells.
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