CD38 expression of tumor cells has been identified as an important prognostic 
factor in B-cell chronic lymphocytic leukemia (B-CLL). Although CD38 is involved 
in effector functions of T cells, the prognostic value of CD38+ T cells has not 
yet been addressed in B-CLL. In the present study, CD38-expression levels in 
B-CLL cells and T cells from 204 patients were analyzed by flow cytometry and 
correlated with clinical and molecular risk parameters. CD38 expression 
significantly differed in the neoplastic clone from patients with low versus 
advanced stage, irrespective of the sex of patients. In contrast, CD38 
expression was generally higher in T cells from female compared with male 
patients but only increased in male patients in a stage-dependent manner. In 
male patients, combined analysis of CD38 in T cells and B-CLL cells identified 4 
subgroups with significantly different treatment-free survival. Multivariate 
analysis including Rai stage and molecular risk parameters of the neoplastic 
clone identified CD38-expression levels in T cells as an independent prognostic 
factor in male patients. Combined analysis of CD38 in B-CLL and T cells is 
superior in predicting outcome of male B-CLL patients than either parameter 
alone. Further studies are needed to elucidate the underlying mechanisms of the 
sex-specific role of CD38+ T cells in B-CLL.