Generating renal cancer-reactive T cells using dendritic cells (DCs) to present autologous tumor.

Dendritic cells (DCs) have been used as professional antigen-presenting cells in vitro to prime T-cell responses. In this study, we generated both CD8+ and CD4+ renal cell carcinoma (RCC)-reactive T cells using a completely autologous system of DCs presenting engulfed whole-tumor cells. We compared DCs presenting RCC tumor cells in different preparations and found ultraviolet-irradiated apoptotic tumor cells to be more immunogenic than necrotic tumor cells or live untreated tumor cells in generating tumor-reactive T cells. In analyzing the T cells generated in this fashion, a CD8+ RCC-reactive T-cell clone generated from a patient recognized an epitope derived from fibroblast growth factor 5 in the context of human leukocyte antigen (HLA) B44*02. CD4+ T cells generated from another patient recognized multiple allogeneic RCC lines expressing HLA-DRbeta1*04, indicating a common shared tumor antigen presented by HLA-DRbeta1*04. The technique of using DCs to present whole-tumor cells can consistently generate both CD4+ and CD8+ RCC-reactive T cells for use in both antigen identification and therapeutic protocols.

Induction of CD4(+) T cell-dependent antitumor immunity by TAT-mediated tumor antigen delivery into dendritic cells.

Dendritic cell-based (DC-based) immunotherapy represents a promising approach to the prevention and treatment of many diseases, including cancer, but current strategies have met with only limited success in clinical and preclinical studies. Previous studies have demonstrated that a TAT peptide derived from the HIV TAT protein has the ability to transduce peptides or proteins into various cells. Here, we describe the use of TAT-mediated delivery of T cell peptides into DCs to prolong antigen presentation and enhance T cell responses. While immunization of mice with DCs pulsed with an antigenic peptide derived from the human TRP2 protein generated partial protective immunity against B16 tumor, immunization with DCs loaded with a TAT-TRP2 peptide resulted in complete protective immunity, as well as significant inhibition of lung metastases in a 3-day tumor model. Although both DC/TRP2 and DC/TAT-TRP2 immunization increased the number of TRP2-specific CD8(+) T cells detected by K(b)/TRP2 tetramers, T cell activity elicited by DC/TAT-TRP2 was three- to tenfold higher than that induced by DC/TRP2. Furthermore, both CD4(+) and CD8(+) T cells were required for antitumor immunity demonstrated by experiments with antibody depletion of subsets of T cells, as well as with various knockout mice. These results suggest that a TAT-mediated antigen delivery system may have important clinical applications for cancer therapy.