Accumulation of benzoporphyrin derivative in malignant and host cell populations of the murine RIF tumor.

The accumulation of benzoporphyrin derivative (BPD) in malignant and host cell populations of the mouse RIF tumor was studied by flow cytometry analysis of cells dissociated from the tumor tissue. The highest cellular BPD levels were found in a subpopulation of tumor associated macrophages (TAMs) characterized by a highly elevated expression of interleukin 2 receptor (F4/80+CD25++), but this selectivity was less pronounced than with photofrin. The BPD levels in tumor associated immune cells other than TAMs were lower than in malignant cells. No significant difference in cellular distribution of BPD was observed with the photosensitizer delivered in liposomes compared to the aqueous solution.