Increased serum levels of soluble Fas in progressive B-CLL

Clinical progression of B-cell chronic lymphocytic leukemia (B-CLL) depends on survival and accumulation of leukemic cells, regulated in part by physi cal cell contact and soluble molecules. Here we have studied the Fas/FasL s ystem in relation to clinical progression in B-CLL. Serum levels of soluble Fas (sFas) and Fast (sFasL) were determined by ELISA in 43 progressive and 40 non-progressive B-CLL patients and in 21 control individuals. Correlati on between sFas serum levels and clinical progression, stage and survival w ere statistically analyzed. We found high levels of sFas in B-CLL sera corr elated with disease progression (p <0.01). In addition, higher sFas levels were found in patients in stages II, III and IV in comparison to patients i n stage 0 (p<0.05, p <0.01, p <0.03, respectively). Survival was significan tly shorter for patients with greater than or equal to6 ng/ml sFas serum le vels, although a multivariate analysis did not show sFas to be a significan t independent prognostic factor. Fresh B-CLL cells showed only low levels o f membrane expression, which were not correlated to sFas levels in serum. I n vitro activation of B-CLL cells increased Fas expression, as reported ear lier, and induced cells to release sFas into the supernatant. In conclusion , our results indicate that sFas in serum may be a useful parameter for the prediction of clinical progression in B-CLL.