title: Inactivation of WBCs in RBC suspensions by photoactive phenothiazine dyes: comparison of dimethylmethylene blue and MB.
abstract: BACKGROUND
  The transfusion of blood components containing WBCs can cause unwanted complications, which include virus transmission, transfusion-associated GVHD, alloimmunization, febrile reactions, and immunomodulation. Phototreatment with 4 microM of dimethylmethylene blue (DMMB) and 13 J per cm(2) of white light irradiation has previously been shown to be an effective way to inactivate different models of enveloped and nonenveloped viruses in RBC suspensions, with minimum damage to RBCs. The present study compares WBC photoinactivation in buffy coat after DMMB or MB phototreatment under virucidal conditions.
  
  
  METHODS
  Buffy coat diluted to 30-percent Hct was treated with the dye and white light. Isolated WBCs were assayed for cell proliferation and viability by an assay using a tetrazolium compound, limiting dilution analysis, DNA fragmentation, and flow cytometry assays.
  
  
  RESULTS
  DMMB and 2.5 J per cm(2) of light phototreatment can inactivate T cells to the limit of detection by limiting dilution analysis (>4.76 log reduction). No WBC proliferation activity was observed after DMMB and 3.8 J per cm(2) of light. DNA degradation after DMMB phototreatment was light dependent. In addition, DMMB phototreatment induced apoptosis in WBCs. In contrast, MB phototreatment under virucidal conditions did not cause significant changes in the viability of WBCs. Neither DNA degradation nor signs of apoptosis were observed after MB phototreatment.
  
  
  CONCLUSIONS
  DMMB phototreatment inactivates T-lymphocytes, the cells that cause GVHD.
authors.affiliation: Product Development Department, Jerome Holland Laboratory, American Red Cross, Rockville, Maryland 20855-2734, USA. skripcha@usa.redcross.org
authors.forename: A A
authors.initials: AA
authors.lastname: Skripchenko
authors.forename: S J
authors.initials: SJ
authors.lastname: Wagner
mesh_terms: D004396:Coloring Agents / Q000494:pharmacology*; D053938:DNA Fragmentation; D004912:Erythrocytes; D005434:Flow Cytometry; D006801:Humans; D007962:Leukocytes / Q000378:metabolism; D007963:Leukocytes, Mononuclear; D008027:Light; D008751:Methylene Blue / Q000031:analogs & derivatives* / Q000494:pharmacology; D010640:Phenothiazines / Q000494:pharmacology*; D017319:Photosensitizing Agents / Q000494:pharmacology; D011419:Propidium / Q000493:pharmacokinetics; D014775:Virus Activation / Q000187:drug effects
chemical_list: D004396:Coloring Agents; D010640:Phenothiazines; D017319:Photosensitizing Agents; D011419:Propidium; C031637:phenothiazine; D008751:Methylene Blue; C016401:1,9-dimethylmethylene blue