In vitro-activated tumor-bearing host T cells and the effectiveness of tumor vaccine immunotherapy.

BACKGROUND AND OBJECTIVE

Vaccination during periods of lymphopenia may facilitate immune responses to weak self-antigens and enhance antitumor immunity. The objective of this study was to determine the effectiveness of tumor vaccine immunotherapy combined with immune reconstruction using tumor-bearing host immune cells in lymphopenia, and to investigate the role of tumor-bearing host T cells activated in vitro during immunotherapy.

DESIGN AND SETTING

Animal study conducted in the First Affiliated Hospital of Xi'an Jiaotong University from January 2009 to January 2010.

PATIENTS AND METHODS

Lymphopenia was induced by cyclophosphamide. A reconstituted immune system with different syngeneic lymphocytes was employed, including lymphocytes from naïve rats (unsensitized group), tumor-bearing rats (tumor-bearing group), and tumor-bearing rats activated in vitro (activated group). All rats were immunized with granulocyte-macrophage colony-stimulating factor (GM-CSF)-modified NuTu-19 ovarian cancer (GM-CSF/NuTu-19) cells. Tumor vaccine-draining lymph nodes (TVDLNs) were harvested, and then stimulated to induce effector T cells (T(E)). T(E) were then adoptively transferred to rats bearing a 3-day pre-established abdominal tumor (NuTu-19), and the survival rate was calculated.

RESULTS

Compared with the unsensitized group, the levels of interleukin-2 (IL-2) were significantly lower in the tumor-bearing group, whereas that of IL-4 were significantly higher (P<.05). The number of CD4+ T cells secreting interferon-γ and the specific cytotoxicity of CD8+ cytotoxic T lymphocytes were significantly lower (P<.05). The survival was significantly higher in the activated group compared with the other groups.

CONCLUSIONS

Lymphocytes from tumor-bearing rats activated in vitro can effectively reverse the immunosuppressive effects of tumor-bearing hosts.