Expression of apoptosis markers on peripheral blood lymphocytes from patients with cutaneous T-cell lymphoma during extracorporeal photochemotherapy

The mechanisms of extracorporeal photochemotherapy (ExP) therapeutic activi ty in cutaneous T-cell lymphomas (CTCLs) are not yet well understood, even though it has been suggested that a major mechanism ma) be induction of apo ptosis. In vitro studies demonstrate that UVA-induced apoptosis is mediated by CD95-Fas expression and inhibited by Bcl-2 up-regulation and that UVA i rradiation is able to down-regulate Bcl-2 expression. High-resolution multi parameter flow-cytometric analyses were used tc, evaluate Bcl-2/CD95-Fas ex pression on phenotypically identifiable circulating clonal T cells from 7 p atients with CTCL (4 with Sezary syndrome and 3 with mycosis fungoides with peripheral involvement) before and during ExP in an attempt to ascertain w hether Bcl-2/CD95-Fas status can be related to the hematologic response. A Bcl-2 normal phenotype before ExP or a normalization in Bcl-2 expression du ring ExP were related to a better clinical response, whereas a persistent B cl-2 high expression was a negative prognostic factor. On the other hand, n o response was found in patients with a CD95-Fas-negative phenotype, wherea s the expression of CD95-Fas was associated with hematologic remission. Alt hough further studies are needed to confirm these preliminary results, this study suggests that Bcl-2 and CD95-Fas expression could be evaluated, toge ther with the other known clinical and immunologic factors, as additional p arameters related to clinical response in patients with CTCL undergoing ExP .