POTENTIATION OF PHOTODYNAMIC THERAPY BY IMMUNOTHERAPY - THE EFFECT OFSCHIZOPHYLLAN (SPG)

Treatment of squamous cell carcinoma (SCCVII) bearing mice with the im munostimulant schizophyllan (SPG) raised the relative content of Mac-1 positive host cells infiltrating the tumor and increased photofrin re tention in these tumors. In vitro colony formation assay following pho tofrin-based photodynamic therapy (PDT) in vivo revealed a greater kil ling of tumor cells in the SPG pre-treated group, particularly pronoun ced when the tumor excision was delayed for 8 h after PDT. The tumor c ure rate increased approximately three times when PDT was preceded by the SPG therapy. In contrast, the administration of SPG after PDT was of no benefit for tumor control.