Background: The symptoms of a 56-year-old man with systemic mastocytosis became worse with exposure to sunlight. We evaluated mast-cell-derived mediators and cytokines before and after exposure to ultraviolet light in the patient.
Methods: The patient was irradiated with middle-wave ultraviolet light, so-called ultraviolet light B, and the levels of mediators and cytokines were measured serially. The point mutation Asp816Val in c-kit was investigated by analyzing polymerase chain reaction products from the complementary DNA of peripheral blood mononuclear cells.
Results: Before irradiation, the levels of mast-cell-derived mediators and metabolites were elevated. Among various cytokines measured, including soluble c-kit and stem cell factor, only the level of nerve growth factor was elevated. After irradiation, the nerve growth factor level was further increased along with the levels of mast-cell-derived mediators and metabolites. The point mutation Asp816Val in c-kit was not detected in peripheral blood mononuclear cells.
Conclusions: Middle-wave ultraviolet light may activate mast cells to release nerve growth factor and mediators in systemic mastocytosis.