Clinical relevance of CD95 (Fas/Apo-1) on T cells of patients with B-cell chronic lymphocytic leukemia. 
Apoptosis mediated via CD95 (Fas/Apo-1) is a key regulator for the biology of normal and malignant lymphocytes.  Although the function of CD95 on B-cell chronic lymphocytic leukemia cells (B-CLL cells) has been studied intensively, the clinical importance of CD95 expression on normal T cells in B-CLL has not been clarified.  This study aimed to investigate whether expression of CD95 on peripheral blood T cells correlates with clinically relevant parameters of B-CLL disease.  Expression of CD95 (Fas/Apo-1) on peripheral blood T lymphocytes of patients with B-CLL was determined using flow cytometry and was correlated with expression of activation markers, sensitivity to apoptosis by anti-CD95, and clinical data, such as blood count, Binet stage, therapy, progression-free probability, and survival probability.  Differential CD95 expression did not correlate with activation markers or with levels of apoptosis through anti-CD95.  However, high levels of CD95 on T cells from B-CLL patients correlated significantly with low lymphocyte doubling time, increased Binet stages, and requirement for chemotherapeutic treatment.  Furthermore, increased cell-surface CD95 on T cells was associated with reduced progression-free probability and poorer survival.  CD95 levels on T cells correlate with the clinical course of B-CLL.  Prospective studies appear warranted to investigate whether CD95 on T cells has a direct influence on B-CLL disease progression.