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Fludarabine and alemtuzumab are routinely used for treatment of B-cell chronic lymphocytic leukemia (B-CLL). The present study aimed to compare the expression of signaling molecules and cytokine production by T cells of B-CLL patients in long-term unmaintained remission/plateau phase following fludarabine or alemtuzumab treatment with that of indolent/untreated B-CLL patients and healthy donors. The frequency and intensity of TCR-CD3ζ chain, p56lck, p59fyn, ZAP-70, PI3-kinase and interferon (IFN)-γ/interleukin (IL)-4 production in CD4 and CD8 T cells was examined by flow cytometry. T-cell function was assessed by stimulation with purified protein derivative (PPD) and phytohemagglutinin (PHA). Despite a reduction in number, the expression of IFN-γ/IL-4 in T-cells in patients was significantly higher than in healthy donors. The intensity of most signaling molecules in treated patients was relatively unaffected vs. healthy donors but lower than untreated-indolent patients. However, the total number of T cells which expressed each of the signaling molecules was decreased in patients, with no difference between fludarabine- and alemtuzumab-treated patients. The T-cell response to PHA but not PPD was reduced in treated patients. The results suggest that, despite some alterations in signaling molecules and a reduction in T-cell number, overall T-cell functions may be relatively well preserved long-term after treatment with fludarabine and alemtuzumab. [ABSTRACT FROM AUTHOR]