Document Type: Original Article

Authors

1 Department of Immunology, School of Medicine, Mazandaran University of Medical Sciences,Sari, Iran

2 2 Student Research Committee, Mazandaran University of Medical Sciences, Sari, Iran

3 Gastrointestinal Cancer Research Center, Mazandaran University of Medical Sciences, Sari, Iran

4 Immunogenetics Research Center, School of Medicine, Mazandaran University of Medical Sciences, Sari, Iran

Abstract

Background: Chronic lymphocytic leukemia (CLL) is the most common adult leukemia in the western world. This health problem is caused due to the accumulation of mature B-lymphocytes in the peripheral blood and bone marrow. In the course of cancer, CD4+ T cells become “exhausted” and characterized with poor effector functions and the expression of multiple inhibitory receptors. Objective: To investigate the frequency and functional properties of exhausted CD4+ T lymphocytes in patients with CLL. Methods: Peripheral blood mononuclear cells were obtained from 25 untreated CLL patients and 15 healthy volunteers. CLL patients were clinically classified according to the Rai staging system. The frequency of CD4+/Tim-3+/PD-1+ cells was obtained by flow cytometry. To evaluate cell proliferation and cytokine production, CD4+ T cells were isolated and stimulated with phytohemagglutinin and PMA/ionomycin. Concentrations of IL-2, IFN-γ, TNF-α, and IL-10 were measured in the culture supernatants of stimulated cells by the ELISA technique. Results: The percentage of CD4+/Tim-3+/PD-1+ cells was significantly higher in CLL patients than that of healthy controls. CD4+ T cells from CLL patients showed lower proliferative responses, a lower production of IL-2, IFN-γ, and TNF-α, and a higher production of IL-10, compared to healthy controls. CD4+ T cells from CLL patients in advanced clinical stages showed more exhaustion features than those of early stages. Conclusion: Given that the exhaustion phase of T cells can be reversible, targeted blocking of immune inhibitory molecules could be a promising tool to restore the host immune responses against leukemic cells in CLL.

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