Abstract Book 2010 - CIMT Annual Meeting

056 Hoyer | Cellular therapy
Examination of T-helper cell / DC cross-talk by the transfection
of T cells with RNA coding for TCRs
Stefanie Hoyer 1 , Sabrina Schievelbein 1 , Gerold Schuler 1 , Jan Dörrie 1 ,*, and Niels Schaft 1 ,*
1 Department of Dermatology, University Hospital Erlangen, Erlangen, Germany
* Contributed equally
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The goal of immunotherapy of cancer is to initiate
an adaptive immune response against the tumor.
But up to now, cancer immunotherapy has mainly
focused on the generation of tumor-specific CD8+
T cells, even though CD4+ T-cell help is also required
for a long-lasting cytotoxic T lymphocyte
response. However, the exact mechanism by
which CD4+ T cells license dendritic cells (DC)
and thereby modulate the priming and expansion
of CTLs is not yet fully understood. For this
purpose, we transferred melanoma-antigen-specific
TCRs by RNA-electroporation into CD4+ T cells
and co-cultured them with peptide-loaded DC to
elucidate T-cell / DC cross-talk. We either introduced
MAGE-A3/HLA-DP4-specific or gp100/HLA-
A2-specific TCR-RNA into CD4+ T cells, which
mainly resulted in antigen-specific Th1 cytokine
secretion after co-cultivation with peptide-loaded
DC. Besides, phenotypic changes were assessed in
a time-dependent manner. We detected a clear antigen-specific
up-regulation of maturation markers
like CD25, CD40, CD80, CD86, and CD70 on both immature
and mature DC after 20 hours of co-cultivation
with T cells. In correlation, CD25 was antigenspecifically
up-regulated as an activation marker
on CD4+ T cells. The early activation marker CD69
was antigen-specifically up-regulated already after
2 hours, while CD27- and CCR7-expression on the
T cells remained almost constant during the stimulation.
Moreover, T-cell activation was completely
cell-cell-contact dependent, while the maturation
of the DC was in part mediated by soluble factors,
as revealed by transwell experiments. These data
indicate that DC / CD4+ T-cell cross-talk is a bidirectional
process. Moreover, we currently examine
the influence of pre-activation of CD4+ T cells on
the antigen-specific cross-talk, and whether there
is an antigen-specific cross-talk between DC and
CD8+ T cells. Since TCR-transfected CD4+ T cells
can induce DC maturation, they may be used to
provide T-cell help to induce more efficient CD8+
T-cell responses for the immunotherapy of cancer.