Photodynamic therapy induced leukocyte adherence in normal subcutaneous but not in tumor microvessels

摘要

Abstract: Leukocyte mediated tissue damage is proposed to contribute to the tumoricidal effect of photodynamic therapy (PDT). To elucidate this hypothesis leukocyte-endothelium interaction and red blood cell velocity in the microvasculature of an amelanotic melanoma and normal tissue in a skin fold chamber preparation were investigated before and after PDT (5 mg/kg Photofrin$+R$/; 630 nm; 10 or 100 J/cm$+2$/). One hour after PDT (10 and 100 J/cm$+2$/) the number of adhering leukocytes increased in subcutaneous but not in tumor microvessels. At this time red blood cell velocity remained unaltered in microvessels of subcutaneous tissue but decreased (10 J/cm$+2$/) and even ceased (100 J/cm$+2$/) in tumor microvessels. These results indicate that tumor destruction induced by PDT is not mediated by leukocyte-endothelium interaction. !12