Impaired Immunity in Patients With Cancer: Influence of Cancer Stage, Chemotherapy, and Cytomegalovirus Infection

According to a survey from Department of Health in 2004, cancer has been the leading cause of death in the Taiwan area. In 2004, people died of cancer, accounting for 27.2 percent of all deaths. The major reason of the superior grade is that cancer has the ability to escape the surveillance of immune system. It is also a main issue to address in medical research.

Dendritic cells (DCs), the most potent APC, are located at sites of pathogen entry, acquire antigens from pathogens or pathogen-infected cells, and process these antigens for both class I and class II presentation. Upon antigen encounter, they termed immature DCs, undergo a maturation process, they are capable to present captured antigens to T cells. This maturation step allows DC migration to trigger adaptive immune responses. These features make DCs very good candidates for therapy against various pathological conditions including malignancies.

Therefore, two concepts in this project will be concerned: one is enhancement of T cell immunity and the other is improvement of the efficiency of DC-tumor fusion. The strategy of enhance T cell is using well-known cytokines, such as IL2, and IL7 to expand the tumor-specific CD4 and CD8 T cells before DC-vaccine treatment. In the past, scientists utilized polyethyleneglycol to fuse cancer cells and dendritic cells. However, the results were devastating. Two new approaches of the DC vaccine will be applied to this study: DC-tumor fusion and DC phagocytosed apoptosed tumor cells. Whole tumor cells will be fused with DCs by combining hypotonic buffer and electrical-based fusion protocols. The safety of hybrid cell vaccination has been shown in clinical trials with some encouraging anti-tumour effects. However, data are as yet insufficient to assess a clear therapeutic benefit. Hopefully, the combination of two strategies will improve the efficiency of DC vaccine and boost survival of cancer patients.

As we have gained a clearer understanding of the cellular and molecular events that modulate antigen presentation and T cell activation in vivo, new strategies have emerged, allowing the development of more potent second generation DC vaccines.