CD8α Coreceptor to Improve TCR Gene Transfer to Treat Melanoma: Down-Regulation of Tumor-Specific Production of IL-4, IL-5, and IL-10

Abstract

Therapeutic success of TCR gene transfer to treat tumors depends on the ability of redirected T cells to become activated upon tumor recognition in vivo. Help provided by tumor-specific Th1 cells is reported to relieve T cells from an anergized state and to induce tumor regression. We recently demonstrated the ability to generate melanoma-specific Th1 cells by genetic introduction of both a CD8-dependent TCR and the CD8α coreceptor into CD4+ T cells. In this study, we analyzed a TCR that binds Ag independently of CD8, a property generally preferred to induce tumor-specific T cell responses, and addressed the contribution of CD8α following introduction into TCR-transduced CD4+ T cells. To this end, primary human CD4+ T cells were gene transferred with a high-avidity TCR, and were shown not only to bind peptide/MHC class I, but also to effectively kill Ag-positive tumor cells in the absence of CD8α. The introduction of CD8α up-regulates the tumor-specific production of TNF-α and IL-2 to some extent, but significantly down-regulates production of IL-4, IL-5, and IL-10 in CD4+ T cells. The introduction of a mutated cysteine motif in CD8α, which prevents its binding to LCK and linker for activation of T cells, did not adversely affect expression and T cell cytotoxicity, but counteracted the CD8α-mediated down-regulation of IL-4 and IL-5, but not IL-10. In conclusion, CD8α down-regulates the production of major Th2-type cytokines, in part mediated by LCK and/or linker for activation of T cells, and may induce differentiation of tumor-specific Th1 cells, which makes this coreceptor an interesting candidate to improve the clinical potential of TCR gene transfer to treat cancer.

An Altered gp100 Peptide Ligand with Decreased Binding by TCR and CD8α Dissects T Cell Cytotoxicity from Production of Cytokines and Activation of NFAT

“…Primary human T lymphocytes of healthy donors, pre-activated with anti-CD3 mAbs were transduced with TCR-positive retroviruses produced by the packaging cell line Phoenix-Amp (32, 33). A retroviral vector encoding human CD8α (34) was used to transduce Jurkat T cells prior to transfer of TCR genes (35). Transduction with Mock genes served as a negative control.…”

MHC-I-restricted melanoma antigen specific TCR-engineered human CD4+ T cells exhibit multifunctional effector and helper responses, in vitro

“…Lately, the use of CD4+ T cells transduced to express the α/β chains of a relevant MHC class I-restricted tumor epitope specific TCR has emerged as a mechanism to achieve that goal [4; 5; 6; 7; 8]. That such MHC class-I restricted epitope specific TCR-engineered CD4+ T cells recognize the epitope on MHC class-I molecules with or without the requirement of co-receptor (i.e., CD8 molecules) engagement and exhibit effector function has been described by several groups in animal models [4; 5] as well as in human systems [9; 10; 11; 12]. We have shown that human CD4+CD25− T cells transduced to express the α/β TCR chains specific for the Melan-A/ MART-1 27–35 epitope, express type I cytokines and exhibit cytolytic function in a co-receptor-independent fashion [12].…”

TCR Gene Transfer: MAGE-C2/HLA-A2 and MAGE-A3/HLA-DP4 Epitopes as Melanoma-Specific Immune Targets

“…The therapeutic benefit of antigen-specific IFN γ production have initiated studies in which CD4 T cells were used as recipient T cells for MHC class I-restricted TCR. Not only can CD4 T cells be functionally endowed with MHC I-restricted TCR via gene transfer [19, 67, 68], but also can genetic cointroduction of CD8 α skew TCR-engineered T cells towards an antigen-specific Th1 type T-cell response [69]. Vice versa, the introduction of a MHC class II TCR and CD4 coreceptor in CD8 T cells may lead to the generation of T cells with combined helper and effector T-cell functions [66].…”