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. STUDY DESIGN AND 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: ). 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. DISCUSSION: 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.