Photodynamic therapy induces an immune response against a bacterial pathogen

Ying Ying Huang, Masamitsu Tanaka, Daniela Vecchio, Maria Garcia-Diaz, Julie Chang, Yuji Morimoto, Michael R. Hamblin

Research output: Contribution to journalReview articlepeer-review

39 Citations (Scopus)


Photodynamic therapy (PDT) employs the triple combination of photosensitizers, visible light and ambient oxygen. When PDT is used for cancer, it has been observed that both arms of the host immune system (innate and adaptive) are activated. When PDT is used for infectious disease, however, it has been assumed that the direct antimicrobial PDT effect dominates. Murine arthritis caused by methicillin-resistant Staphylococcus aureus in the knee failed to respond to PDT with intravenously injected Photofrin®. PDT with intra-articular Photofrin produced a biphasic dose response that killed bacteria without destroying host neutrophils. Methylene blue was the optimum photosensitizer to kill bacteria while preserving neutrophils. We used bioluminescence imaging to noninvasively monitor murine bacterial arthritis and found that PDT with intra-articular methylene blue was not only effective, but when used before infection, could protect the mice against a subsequent bacterial challenge. The data emphasize the importance of considering the host immune response in PDT for infectious disease.

Original languageEnglish
Pages (from-to)479-494
Number of pages16
JournalExpert Review of Clinical Immunology
Issue number5
Publication statusPublished - Jul 2012
Externally publishedYes


  • Photofrin®
  • bacterial arthritis
  • bioluminescence imaging
  • methicillin-resistant Staphylococcus aureus
  • methylene blue
  • neutrophils
  • photodynamic therapy
  • preventative PDT

ASJC Scopus subject areas

  • Immunology and Allergy
  • Immunology


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