Extracorporeal photopheresis technical aspects

Extracorporeal photochemotherapy is a monotherapy first developed by Edelson et al. in 1987. It is a therapy in which 8-methoxypsoralen (8-MOP) containing lymphocytes are exposed to a long wavelength ultraviolet radiation (UVA) in an extracorporeal system. The initial design of the treatment was based on the use of the UVAR system (Therakos) for both the collection and photoirradiation of the mononuclear cells. This machine is replaced now by XTS apparatus, which is fully automatic and has integrated the fluid logic module (the "heart" of the system). Another principle is used: the two independent steps technique. It consists in first collection of mononuclear cells by a continuous blood cell separator and secondly irradiation in an independent machine: UV-MATIC irradiator (VILBER LOURMAT). These three techniques are analyzed through numerous parameters: technical, biological, hematological data. In the future, we consider we need to precise our requirements for adequate UVA energy and 8-MOP concentration. We also have to define therapeutic dose of irradiated cells and so standardize the process.