Review
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World J Immunol. Mar 27, 2014; 4(1): 1-11
Published online Mar 27, 2014. doi: 10.5411/wji.v4.i1.1
Immune response after photodynamic therapy increases anti-cancer and anti-bacterial effects
Eleonora Reginato, Peter Wolf, Michael R Hamblin
Eleonora Reginato, Michael R Hamblin, Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, MA 02114, United States
Eleonora Reginato, Peter Wolf, Department of Dermatology, Medical University of Graz, Graz 8036, Austria
Michael R Hamblin, Department of Dermatology, Harvard Medical School, Boston, MA 02115, United States
Michael R Hamblin, Harvard-MIT Division of Health Science and Technology, Boston, MA 02139, United States
Author contributions: All authors contributed to this paper.
Supported by United States National Institute of Health grant AI050875; the PhD program of the Medical University of Graz, Austria, to Reginato E
Correspondence to: Michael R Hamblin, PhD, Wellman Center for Photomedicine, Massachusetts General Hospital, 55 Fruit St, Boston, MA 02114, United States. hamblin@helix.mgh.harvard.edu
Telephone: +1-617-7266182 Fax: +1-617-7266566
Received: October 17, 2013
Revised: December 20, 2013
Accepted: February 16, 2014
Published online: March 27, 2014
Processing time: 159 Days and 19.2 Hours
Abstract

Photodynamic therapy (PDT) is a clinically approved procedure for treatment of cancer and infections. PDT involves systemic or topical administration of a photosensitizer (PS), followed by irradiation of the diseased area with light of a wavelength corresponding to an absorbance band of the PS. In the presence of oxygen, a photochemical reaction is initiated, leading to the generation of reactive oxygen species and cell death. Besides causing direct cytotoxic effects on illuminated tumor cells, PDT is known to cause damage to the tumor vasculature and induce the release of pro-inflammatory molecules. Pre-clinical and clinical studies have demonstrated that PDT is capable of affecting both the innate and adaptive arms of the immune system. Immune stimulatory properties of PDT may increase its beneficial effects giving the therapy wider potential to become more extensively used in clinical practice. Besides stimulating tumor-specific cytotoxic T-cells capable to destroy distant untreated tumor cells, PDT leads to development of anti-tumor memory immunity that can potentially prevent the recurrence of cancer. The immunological effects of PDT make the therapy more effective also when used for treatment of bacterial infections, due to an augmented infiltration of neutrophils into the infected regions that seems to potentiate the outcome of the treatment.

Keywords: Photodynamic therapy; Anti-tumor immunity; T-cell activation; Damage-associated molecular patterns; Inflammatory cells

Core tip: The immune stimulatory properties of photodynamic therapy (PDT) make this therapy one of the most promising therapeutic procedures for the management of cancer lesions and microbial infections. This review will focus on the current knowledge of the innate and adaptive immune responses induced by PDT against tumors and pathogens.