抄録
We have conducted photoimmunotherapy experiments on a malignant tumor using a photosensitizer, lumin, with a laser light. Lumin is a potent cell activating agent and a photosensitizer characterized by typical absorption peaks at 670nm and 770nm. To clarify macrophage activity enhanced by lumin administration in light irradiation in the vicinity of absorption peaks, three light sources were used; i. e., a white lamp, a He-Ne laser (632.8nm) and a semiconductor laser diode (780nm). The results showed that a small dose of lumin (5ng/ml) with near-infrared laser light of 780nm (energy: about 2×10-3J/cm2) dramatically enhanced the macrophage activity. To study the efficacy of photoimmunotherapy, a human lung cancer was grafted onto nude mice. After the tumor hypertrophied, lumin was injected into the tumor six times. The tumor was exposed to near-infrared laser light (2mW, 1min) every other day for two weeks. The whole tumor was strongly cicatrized by collagen fiber from the stroma and removed 15 weeks after the treatment. The immunological function was investigated using flow cytometric assay, which was analyzed by the two-color method based on immunofluorescence labeling with specific monoclonal antibodies for the sampling of 104cells harvested from mouse peripheral blood. At 40 weeks, the ratio of T and B cells of the non-treated mice (hypertrophied tumor) was 0.29, whereas that of the treated mice (cicatrized tumor) was 0.71. Thus, it was clarified that the immune function was enhanced by the photoimmunological treatment. These results demonstrated that photoimmunotherapy with lumin administration and laser light irradiation is a reliable method of cancer treatment without any side effects.
