Cell biology of hematoporphyrin derivative (HPD).

Tissue culture cells were treated with hematoporphyrin derivative (HPD) and analyzed for (1) HPD uptake, (2) HPD washout, and (3) fluorescence changes. The absorption peaks were the same for HPD in solution and HPD bound to cells. HPD was taken up by all cell types rapidly within the first 10 hours of exposure, and leveled off by 20 hours of exposure. HPD came out of all cell types to control levels by 72 hours after removal of the HPD bathing solution. The HPD appeared to come out of the malignant 3-T-12 cells more slowly than from the parental (non-malignant) 3-T-3 cells. The fluorescence spectrum of HPD-treated cells changed markedly from the time that the bathing HPD solution was removed from the cells. As time progressed the weakly fluorescent 590-nm peak increased greatly and the 615-nm and 630-nm peaks decreased significantly.