Photodynamic effect of haematoporphyrin throughout the cell cycle of the human cell line NHIK 3025 cultivated in vitro.

Cells from the established cell line NHIK 3025 were synchronized by repeated mitotic selections. Survival of the synchronized cells after treatment with haematoporphyrin and near-UV light was measured by testing the capacity of the cells to form macroscopic colonies. The sensitivity to photodynamic inactivation was small in early G1, late S and G2. The sensitivity increased throughout late G1 and early S to a maximum in mid S. More than a 100-fold variation is found in the survival after 20 min irradiation in the presence of 4 X 10(-4)M haematoporphyrin.