EXTRACORPOREAL PHOTOCHEMOTHERAPY - EVALUATION OF 2 TECHNIQUES AND USEIN CONNECTIVE-TISSUE DISORDERS

Extracorporeal photochemotherapy (ECP) consists of collection of monon uclear cells, their irradiation with UV-A light in the presence of a p hotoactivable molecule-8-methoxy-psoralen (8-MOP) being the most widel y used-and their reinjection into a patient. Two technical approaches have been developed. The photopheresis procedure involves four steps: (i) 8-MOP is given to the patient orally, 2 h before collection of whi te blood cells; (ii) a discontinuous flow cell separator (UVAR, Therak os, West Chester, PA, U.S.A.) is used for cell collection. The final p roduct (740 mL) has a hematocrit of 4.5 +/- 1.7%); (iii) irradiation, performed with the same UVAR apparatus, begins before all the cells ar e collected, and lasts for 180 min after collection; and (iv) after ir radiation, the buffy-coat is reinjected into the patient. We developed a technique summarized as follows: (i) mononuclear cell collection is performed using the Spectra (Cobe, Denver, CO, U.S.A.) cell separator , which provides a highly enriched mononuclear cell concentrate (alway s >90% purity), in a small volume <150 mL, subsequently adjusted to 30 0 mL for irradiation. Hematocrit of the final product is always <2%. ( ii) Soluble 8-MOP is added to the mononuclear cell concentrate at a fi nal concentration of 200 ng/mL. (iii) Mononuclear cell concentrate is transferred in an EVA plastic bag (Macopharma, Tourcoing, France) to e nsure an efficient irradiation with a UV irradiator (Vilber Lourmat, M arne-la-Vallee, France). (iv) After irradiation at 2 J/cm2 (time <20 m in), the cells are reinfused into the patient. Experimental and clinic al data suggest that ECP has potential applications in the treatment o f connective tissue disorders, such as systemic sclerosis and rheumato id arthritis. Although encouraging data have been obtained, further cl inical trials are warranted to establish the role of this therapy in t hese indications.