Increased CD39 expression on CD4 T lymphocytes has clinical and prognostic significance in chronic lymphocytic leukemia.

Chronic lymphocytic leukemia (CLL) cells depend on their microenvironment for proliferation and survival. Ectonucleotidase CD39 has anti-inflammatory properties as it hydrolyzes proinflammatory extracellular ATP, generates anti-inflammatory adenosine, and also protects regulatory T cells from ATP-induced cell death. In this study, we investigated the clinical significance of CD39 expression on CD4 T cells in 62 patients with CLL as well as its compartmental regulation and explored the possible mechanisms for its induction. Compared to healthy individuals, CD4CD39 lymphocytes were increased in the peripheral blood of patients with CLL and correlated with the advanced stage of disease. CD4CD39 cells were also higher in patients with CLL, who needed therapeutic intervention, and in those who had unmutated immunoglobulin heavy chain variable region gene, were ZAP70 or had β2-microglobulin levels of >3 g/L. There were more CD4CD39 lymphocytes in the bone marrow compartment than in the peripheral blood, and in vitro studies showed that CD39 can be induced on CD4 cells by exposure to ATP or indirectly, following B cell receptor engagement. This may support the notion that the leukemic cells contribute to create an immune-subversive environment, and perhaps to a poorer prognosis. CD39 may also serve as a future target for the development of novel therapies with immune-modulating antitumor agents in CLL. [ABSTRACT FROM AUTHOR]