Sery T W
Cancer Res. 1979 Jan;39(1):96-100.
Hematoporphyrin and white light exerted a lethal effect on two cell lines of retinoblastoma cells. The lowest values of dye concentration and light exposure capable of killing an entire cell population were, respectively, 2 X 10(-5) M and 6 min exposure to an irradiance of 6.0 microwatts/sq mm. Cells exposed to light in the presence of the dye did not require lengthy incubation periods but were rapidly killed with increasing periods of light exposure. Cells washed free of the dye, however, required a minimum sensitizing period of 3.5 hr to achieve a value close to 100% cell death. An inhibitor of this photodynamic process was demonstrated in normal serum. When the concentration of either fetal calf serum, rabbit serum, or rabbit plasma was increased to 25% from a standard 10%, there was as much as a 100-fold greater requirement of hematoporphyrin concentration to produce the same lethal response. The suggested explanation for this phenomenon is a porphyrin-binding plasma factor, hemopexin, which is a natural beta-glycoprotein believed to be responsible for the transport of circulating porphyrins to the liver for their elimination. Retinoblastoma cells grow in suspension and thereby provide an excellent tool for study of photosensitive dyes, especially in the case of the rapidly growing Y79 cell line.
血卟啉和白光对两种视网膜母细胞瘤细胞系具有致死作用。能够杀死整个细胞群体的最低染料浓度和光照值分别为2×10⁻⁵ M以及在6.0微瓦/平方毫米的辐照度下照射6分钟。在染料存在的情况下接受光照的细胞无需长时间孵育，但随着光照时间的增加会迅速死亡。然而，洗去染料的细胞需要至少3.5小时的敏化期才能达到接近100%的细胞死亡率。在正常血清中证实了这种光动力过程的一种抑制剂。当胎牛血清、兔血清或兔血浆的浓度从标准的10%增加到25%时，产生相同致死反应所需的血卟啉浓度要高出多达100倍。对这种现象的推测性解释是一种卟啉结合血浆因子——血红素结合蛋白，它是一种天然的β-糖蛋白，被认为负责将循环中的卟啉转运到肝脏进行清除。视网膜母细胞瘤细胞悬浮生长，因此为研究光敏染料提供了一个极好的工具，特别是对于快速生长的Y79细胞系而言。
