title: Immune response after photodynamic therapy increases anti-cancer and anti-bacterial effects.
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. Be sides 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.
authors.affiliation: Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, MA 02114, United States.
authors.forename: Eleonora
authors.initials: E
authors.lastname: Reginato
authors.affiliation: Department of Dermatology, Medical University of Graz, Graz 8036, Austria.
authors.forename: Peter
authors.initials: P
authors.lastname: Wolf
authors.affiliation: Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, MA 02114, United States.
authors.forename: Michael R
authors.initials: MR
authors.lastname: Hamblin
keywords: Anti-tumor immunity; Damage-associated molecular patterns; Inflammatory cells; Photodynamic therapy; T-cell activation