Photodynamic therapy (PDT) uses non-toxic photosensitizers and harmless visible light in combination with oxygen to produce cytotoxic reactive oxygen species that kill malignant cells by apoptosis and/or necrosis, shut down the tumour microvasculature and stimulate the host immune system. In contrast to surgery, radiotherapy and chemotherapy that are mostly immunosuppressive, PDT causes acute inflammation, expression of heat-shock proteins, invasion and infiltration of the tumour by leukocytes, and might increase the presentation of tumour-derived antigens to T cells.
Bibliographical noteFunding Information:
A.P.C. was supported by a US Department of Defense CDMRP Breast Cancer Research Grant. M.R.H. was supported by the US National Institutes of Health. We thank T. N. Demidova for help and advice.