Modulation of tumor response to photodynamic therapy in severe combined immunodeficient (SCID) mice by adoptively transferred lymphoid cells

摘要

Abstract: Photodynamic treatment, consisting of intravenous injection of Photofrin$+R$/ (10 mg/kg) followed by exposure to 110 J/cm$+2$/ of 630 plus or minus 10 nm light 24 hours later, cured 100% of EMT6 tumors (murine mammary sarcoma) growing in syngeneic immunocompetent BALB/C mice. In contrast, the same treatment produced no cures of EMT6 tumors growing in either nude or SCID mice (immunodeficient strains). EMT6 tumors growing in BALB/C and SCID mice showed no difference in either the level of Photofrin$+R$/ accumulated per gram of tumor tissue, or the extent of tumor cell killing during the first 24 hours post photodynamic therapy (PDT). In an attempt to improve the sensitivity to PDT of EMT6 tumors growing in SCID mice, these hosts were given either splenic T lymphocytes or whole bone marrow from BALB/C mice. The adoptive transfer of lymphocytes 9 days before PDT was successful in delaying tumor recurrence but produced no cures. A better improvement in PDT response was obtained with tumors growing in SCID mice reconstituted with BALB/C bone marrow (tumor cure rate of 63%). The results of this study demonstrate that, at least with the EMT6 tumor model, antitumor immune activity mediated by lymphoid cell populations makes an important contribution to the curative effect of PDT. !11