title: Technical comparison of four different extracorporeal photopheresis systems.
abstract: BACKGROUND
  Extracorporeal photopheresis (ECP) is a therapeutic technique that combines leukapheresis and ultraviolet (UV)A irradiation of the leukapheresate after 8-methoxypsoralen treatment with subsequent retransfusion. It can be achieved with a single device (online) or by combining an apheresis machine with a separate UVA light source (offline). The comparability of both established methods is unknown.
  
  
  METHODS
  In a prospective setting, four ECP systems were evaluated: one with integrated UVA irradiation for online ECP (Therakos) and three with external UVA irradiation for offline ECP (Amicus, Optia, and Cobe Spectra). Apheresis variables and cell counts were determined by methods including flow cytometry.
  
  
  RESULTS
  The duration of apheresis ranged from 120 minutes (Amicus, Optia) to 275 minutes (Therakos). Mononuclear cell (MNC) counts in the treatment bags were comparable between offline ECP methods (median, 57 × 108- 66 × 108) and lower for online ECP (14 × 108). CD16+ monocytes were abundant in online ECP (82%) but rarer in offline ECP (median, 14% - 19%). Hematocrit ranged from 0.1% (Therakos) to 8% (Amicus). There were no side effects in any patients.
  
  
  CONCLUSIONS
  All offline ECP systems studied yielded comparable cellular compositions and highly enriched populations of MNCs. In contrast, white blood cells from online ECP displayed enrichment of nonclassical monocytes. The relevance of these findings is unknown as there is no established biomarker to predict the therapeutic efficacy of these procedures.
authors.affiliation: Institute for Clinical Chemistry and Laboratory Medicine, University Hospital Regensburg, Regensburg, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Brosig
authors.affiliation: Institute for Clinical Chemistry and Laboratory Medicine, University Hospital Regensburg, Regensburg, Germany.
authors.forename: Viola
authors.initials: V
authors.lastname: Hähnel
authors.affiliation: Institute for Clinical Chemistry and Laboratory Medicine, University Hospital Regensburg, Regensburg, Germany.
authors.forename: Evelyn
authors.initials: E
authors.lastname: Orsó
authors.affiliation: Department of Hematology and Oncology, University Hospital Regensburg, Regensburg, Germany.
authors.forename: Daniel
authors.initials: D
authors.lastname: Wolff
authors.affiliation: Department of Hematology and Oncology, University Hospital Regensburg, Regensburg, Germany.
authors.forename: Ernst
authors.initials: E
authors.lastname: Holler
authors.affiliation: Institute for Clinical Chemistry and Laboratory Medicine, University Hospital Regensburg, Regensburg, Germany. norbert.ahrens@ukr.de.
authors.forename: Norbert
authors.initials: N
authors.lastname: Ahrens
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001781:Blood Component Removal; D002452:Cell Count; D005260:Female; D006801:Humans; D007958:Leukocyte Count; D008297:Male; D008875:Middle Aged; D009000:Monocytes / Q000166:cytology; D009862:Online Systems / Q000592:standards; D017893:Photopheresis / Q000295:instrumentation* / Q000379:methods; D011446:Prospective Studies; D014466:Ultraviolet Rays; D055815:Young Adult