Photodynamic therapy plus regulatory T-cell depletion produces immunity against a mouse tumour that expresses a self-antigen

E. Reginato, P. Mroz, H. Chung, M. Kawakubo, P. Wolf, M. R. Hamblin

Research output: Contribution to journalArticlepeer-review

47 Scopus citations


Background:Photodynamic therapy (PDT) can lead to development of antigen-specific immune response and PDT-mediated immunity can be potentiated by T regulatory cell (Treg) depletion. We investigated whether the combination of PDT with cyclophosphamide (CY) could foster immunity against wild-type tumours expressing self-antigen (gp70).Methods:Mice with CT26 tumours were treated with PDT alone or in combination with low-dose CY. T regulatory cell numbers and transforming growth factor-β (TGF-β) levels were measured at several time points after treatment. Mice cured by PDT+CY were rechallenged with CT26 and monitored for long-term survival.Results:Photodynamic therapy+CY led to complete tumour regression and long-term survival in 90% of treated mice while the absolute numbers of Treg decreased after PDT+CY and the TGF-β levels were reduced to a level comparable to naïve mice. Sixty-five percent of the mice treated with PDT+CY that survived over 90 days tumour free rejected the rechallenge with the same tumour when a second dose of CY was administered before rechallenge but not without.Conclusion:Administration of CY before PDT led to depletion of Treg and potentiated PDT-mediated immunity, leading to long-term survival and development of memory immunity that was only uncovered by second Treg depletion.

Original languageEnglish (US)
Pages (from-to)2167-2174
Number of pages8
JournalBritish Journal of Cancer
Issue number8
StatePublished - Oct 15 2013
Externally publishedYes

Bibliographical note

Funding Information:
Research in the Hamblin laboratory is supported by US NIH grant AI050875. ER was supported by the PhD program of the Medical University of Graz, Graz, Austria.


  • CT26 tumour
  • TGF β
  • anti-tumour immunity
  • photodynamic therapy
  • regulatory T cells


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