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Immunological Aspects of Photodynamic Therapy of Liver Tumors in a Rat Model for Colorectal Cancer ¶
Author(s) -
Van Duijnhoven Frederieke H.,
Aalbers Remco I. J. M.,
Rovers Jeroen P.,
Terpstra Onno T.,
Kuppen Peter J. K.
Publication year - 2003
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1562/0031-8655(2003)0780235iaopto2.0.co2
Subject(s) - photodynamic therapy , colorectal cancer , cancer research , medicine , cancer , liver cancer , cancer therapy , oncology , chemistry , organic chemistry
We have investigated tumor immunological effects of photodynamic therapy (PDT) of liver metastases. Livers of Wag/Rij rats were inoculated with three tumors of a syngeneic rat colon carcinoma cell line, CC531. One tumor in each rat was illuminated, with or without previous administration of the photosensitizer meta tetrahydroxyphenylchlorin (mTHPC). PDT was effective in causing necrosis of tumors, but it did not affect the growth rate of nearby, nonilluminated tumors in the liver. Immunological staining of tumors showed natural killer (NK) cells to be significantly lower in PDT‐treated tumors than in control tumors ( P < 0.05). T cells in PDT‐treated tumors and in their margins were lower than in tumors that received only sensitizer or only illumination ( P = 0.015) at day 2 after treatment but reappeared at the tumor margins from day 7 after treatment. For macrophages, a similar pattern was found. NK cells, T cells or macrophages in nonilluminated tumors in mTHPC‐treated rats did not increase significantly when compared with tumors in rats without mTHPC treatment. These findings indicated that no antitumor effect of a systemic immune response was present, as measured by the effect of PDT on growth of distant tumors and the number of T lymphocytes, NK cells and macrophages in these tumors.