Activation of GILZ gene by photoactivated 8-methoxypsoralen: Potential role of immunoregulatory dendritic cells in extracorporeal photochemotherapy

Jeffrey S. Futterleib, Hao Feng, Robert E. Tigelaar, Jaehyuk Choi, Richard L. Edelson*

*Corresponding author for this work

Research output: Contribution to journalArticle

16 Scopus citations


Extracorporeal photochemotherapy (ECP) is a widely used method for either immunization against cutaneous T cell lymphoma or immunosuppression of graft- versus-host disease and organ transplant rejection (OTR). Leukapheresed blood is routed through a chamber, in which 8-methoxypsoralen is activated by ultraviolet energy (PUVA), thereby causing DNA crosslinks in processed leukocytes. Return of ECP-processed mononuclear leukocytes to the patient then modulates aberrant T cell immunity. Since interaction with the ECP flow chamber induces monocyte-to-dendritic antigen presenting cell (DC) maturation, we examined the possibility that PUVA may direct the most heavily exposed monocytes to differentiate into tolerogenic DC, while the least exposed DC might remain immunogenic. Expression of the glucocorticoid-induced leucine zipper (GILZ) gene is a distinguishing marker of tolerogenic DC. We report that PUVA directly stimulates GILZ expression. PUVA-exposed DC up-regulated GILZ, down-regulated costimulatory CD80 and CD86, became resistant to Toll-like receptor-induced maturation, increased IL-10 production and decreased IL-12p70 production, all features of immunosuppressive DC. Knockdown of GILZ with siRNA reduced IL-10 and increased IL-12p70 production, demonstrating that GILZ is critical for this profile. PUVA-induction of GILZ expression by DC may help explain how ECP suppresses GVHD and OTR. Conversely, those ECP-processed monocytes minimally exposed to PUVA may mediate ECP's immunogenic effects.

Original languageEnglish (US)
Pages (from-to)379-387
Number of pages9
JournalTransfusion and Apheresis Science
Issue number3
StatePublished - Jan 1 2014



  • Dendritic cells
  • Extracorporeal photochemotherapy
  • GILZ
  • Immunoregulation
  • Regulatory T cells

ASJC Scopus subject areas

  • Hematology

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