Targeting the Wilms Tumor Antigen 1 by TCR Gene Transfer: TCR Variants Improve Tetramer Binding but Not the Function of Gene Modified Human T Cells

Department of Immunology and Molecular Pathology, University College London, Hampstead Campus, Royal Free Hospital, London, United Kingdom.
The Journal of Immunology (Impact Factor: 4.92). 12/2007; 179(9):5803-10. DOI: 10.4049/jimmunol.179.9.5803
Source: PubMed


We have previously described the functional activity of a human TCR specific for an HLA-A2-presented peptide derived from the Wilms tumor Ag 1 (WT1). Recent studies showed that the expression and function of human TCR was improved by the introduction of an additional disulfide bond between the alpha- and beta-chains or by the exchange of the human constant region for murine sequences. In this study, we analyzed the functional activity of WT1-TCR variants expressed in Jurkat cells and in primary T cells. The introduction of cysteine residues or murine constant sequences into the WT1-TCR did not result in a global reduction of mispairing with wild-type TCR chains. Instead, the level of mispairing was affected by the variable region sequences of the wild-type TCR chains. The analysis of freshly transduced peripheral blood T cells showed that the transfer of modified TCR constructs generated a higher frequency of Ag-responsive T cells than the transfer of the wild-type TCR. After several rounds of peptide stimulation this difference was no longer observed, as all transduced T cell populations accumulated approximately 90% of Ag-responsive T cells. Although the Ag-responsive T cells expressing the modified TCR bound the HLA-A2/WT1 tetramer more efficiently than T cells expressing the wild-type TCR, this did not improve the avidity of transduced T cells nor did it result in a measurable enhancement in IFN-gamma production and cytotoxic activity. This indicated that the enhanced tetramer binding of modified WT1-TCR variants was not associated with improved WT1-specific T cell function.

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    • "Down-modulation of the WT1 T-cell receptor (TCR) is associated with a central memory phenotype, and high-affinity TCR mediates faster TCR down-regulation. The WT1-specific T cells proliferate and produce IFNγ and interleukin (IL)-2 in response to WT1 [6]. The authors concluded that the APCs need to express greater than 200 WT1 antigens to achieve TCR triggering and subsequent Tcell activation. "
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    • "However, consistent with published data [34], cyclic antigen-specific stimulations successfully stabilized the expression of the transferred CL3 TCR in the transduced T cells. It is possible that the progressive stabilization of the transferred CL3 TCR expression on the membrane of the transduced T cells might be due to a selection in culture of a limited set of T cell clones whose endogenous TCR is permissive for the expression of the exogenous one. "
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