Dendritic cell maturation induced by delivery of ultraviolet-mediated apoptotic colorectal cancer cell lines.

BACKGROUND

Dendritic cells (DCs) play a critical role in the immune response. The aim of this study was to investigate apoptotic tumor cells as an antigen source for DC maturation.

MATERIALS AND METHODS

We compared the efficacy of ultraviolet (UV)-irradiation with that of gamma-irradiation in the induction of apoptosis of tumor cells. Phenotypic and functional changes of DCs were analyzed after co-incubation with UV-irradiated tumor cells.

RESULTS

UV-irradiation (1.8 J/cm2) was a more reliable method of inducing apoptosis than gamma-irradiation (20,000 rad). The expression of costimulatory molecules on DCs was upregulated after co-incubation with UV-irradiated tumor cells. When we performed allogeneic mixed lymphocyte reaction assay, UV-irradiated tumor cells-pulsed DCs stimulated allogeneic T lymphocytes more efficiently than DCs pulsed with gamma-irradiated cells (HT29, p = 0.0419 and WiDr, p = 0.0076).

CONCLUSION

UV-irradiation reliably induces apoptosis in cultured colorectal cancer cells. DCs mature in function and expression of costimulatory molecules after co-incubation with apoptotic tumor cells. The clinical implications warrant further study.