PHOTOPHERESIS TREATMENT ENHANCES CD95 (FAS) EXPRESSION IN CIRCULATINGLYMPHOCYTES OF PATIENTS WITH SYSTEMIC-SCLEROSIS AND INDUCES APOPTOSIS

We investigated the effects of photopheresis in systemic sclerosis by analysing its influence on lymphocytes with regard to apoptosis and ex pression of bcl-2 and fas. Peripheral blood lymphocytes isolated immed iately before and 24 h after photopheresis were investigated for apopt osis, bcl-2 and fas expression by fluorocytometry, and compared to con trols. In addition, leucocytes from systemic sclerosis patients taken directly from the photopheresis system were tested for apoptosis after 24 h in culture. fas expression was similar in controls and patients with systemic sclerosis just before photopheresis, but increased 24 h after photopheresis, mainly due to an increase of CD4(+)CD95(+) cells. bcl-2 was overexpressed in scleroderma peripheral lymphocytes, but no t influenced by photopheresis. As compared to healthy controls, the pe rcentage of apoptotic cells 24 h after photopheresis was high in cultu red lymphocytes, but not es vivo. The significant increase in fas on p eripheral lymphocytes observed in this study may be a major operative mechanism of photopheresis in addition to (and possibly related to) th e induction of apoptosis.