Photodynamic effects on human cells exposed to light in the presence of hematoporphyrin. Localization of the active dye.

Human cells of the line NHIK 3025 were exposed to light in the presence of hematoporphyrin. Cellular inactivation, induction of single-strand breaks in the DNA and cellular uptake of hematoporphyrin were measured under different conditions. It was concluded that hematoporphyrin bound to or taken up by the cells leads to photoinactivation and photoinduction of single-strand breaks in the DAN, while hematoporphyrin present in the medium outside the cells is of no significant importance.