Effect of combined photodynamic and chemotherapeutic treatment on lymphoma cells in vitro

We investigated the cytotoxic and apoptotic effects of a combination of photodynamic therapy (PDT) and cisplatin (CDDP) on L5178Y (LY) cells. Treatment with PDT by photofrin® (5 μg/ml) alone or with CDDP (20 μg/ml) alone killed 41.5±8.5% or 42.9±6.5% of LY cells, respectively, while a combination of these two treatments killed 99.7±0.6%. Apoptotic cell death after combination treatment was also revealed to be 49.6±7.8% compared to 12.4±3.4% after PDT alone, and 18.8±2.6% after CDDP. This study demonstrated that combined treatment of PDT and CDDP results in enhanced apoptotic cell death as well as a cytotoxic effect on LY cells.