title: Photodynamic therapy enhancement of antitumor immunity is regulated by neutrophils.
abstract: Photodynamic therapy (PDT) is a Food and Drug Administration-approved local cancer treatment that can be curative of early disease and palliative in advanced disease. PDT of murine tumors results in regimen-dependent induction of an acute local inflammatory reaction, characterized in part by rapid neutrophil infiltration into the treated tumor bed. In this study, we show that a PDT regimen that induced a high level of neutrophilic infiltrate generated tumor-specific primary and memory CD8(+) T-cell responses. In contrast, immune cells isolated from mice treated with a PDT regimen that induced little or no neutrophilic infiltrate exhibited minimal antitumor immunity. Mice defective in neutrophil homing to peripheral tissues (CXCR2(-/-) mice) or mice depleted of neutrophils were unable to mount strong antitumor CD8(+) T-cell responses following PDT. Neutrophils seemed to be directly affecting T-cell proliferation and/or survival rather than dendritic cell maturation or T-cell migration. These novel findings indicate that by augmenting T-cell proliferation and/or survival, tumor-infiltrating neutrophils play an essential role in establishment of antitumor immunity following PDT. Furthermore, our results may suggest a mechanism by which neutrophils might affect antitumor immunity following other inflammation-inducing cancer therapies. Our findings lay the foundation for the rational design of PDT regimens that lead to optimal enhancement of antitumor immunity in a clinical setting. Immune-enhancing PDT regimens may then be combined with treatments that result in optimal ablation of primary tumors, thus inhibiting growth of primary tumor and controlling disseminated disease.
authors.affiliation: Department of Cell Stress Biology and the Photodynamic Therapy Center, Roswell Park Cancer Institute, Buffalo, NY 14263, USA.
authors.forename: Philaretos C
authors.initials: PC
authors.lastname: Kousis
authors.forename: Barbara W
authors.initials: BW
authors.lastname: Henderson
authors.forename: Patricia G
authors.initials: PG
authors.lastname: Maier
authors.forename: Sandra O
authors.initials: SO
authors.lastname: Gollnick
mesh_terms: D000818:Animals; D039481:CD11b Antigen / Q000032:analysis; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D002465:Cell Movement; D003713:Dendritic Cells / Q000502:physiology; D007249:Inflammation / Q000276:immunology; D008213:Lymphocyte Activation; D051379:Mice; D008807:Mice, Inbred BALB C; D009374:Neoplasms, Experimental / Q000188:drug therapy* / Q000276:immunology*; D009504:Neutrophils / Q000502:physiology*; D010778:Photochemotherapy; D023063:Receptors, Interleukin-8B / Q000502:physiology
chemical_list: D039481:CD11b Antigen; D023063:Receptors, Interleukin-8B