Association between seropositivity for cytomegalovirus (CMV) and CD4+ cytotoxic T cells expansions in patients with B-cell Chronic Lymphocyte Leukaemia (B-CLL) and healthy controls

B cell chronic lymphocytic leukaemia (B-CLL) is characterized by the clonal expansion of CD5+CD19+CD23+ B cells. During the course of B-CLL, the expansion of neoplastic clone is accompanied by a disbalance between CD4+/CD8+ T cells and by deficiency of T cell function. We have previously shown an expansion of CD4+ perforin (PF)+ cytotoxic T cells (cytT) with undefined specificity in patients with B-CLL. It has been demonstrated by others that the expansion of CD4+PF+ T cells in control individuals is often associated with chronic viral infections. Taking into consideration that B-CLL patients are immunocompromised, with frequent viral infections, we investigated the role of CD4+PF+ cytotoxic T cells in immune responses to one of the most common chronic viral infections - human cytomegalovirus (hCMV). We studied an association of cytT cell frequencies with the chronic CMV infection in 32 B-CLL patients and 18 age-matched healthy controls. Peripheral blood mononuclear cells (PBMCs) were immunostained with anti-CD4~PerCP monoclonal antibodies (mAb), fixed, permeabilised and immunostained with anti-PF~FITC mAb. Cells were fixed and analyzed by flow cytometry. Serum samples were routinely tested for anti-IgG antibodies to CMV. Here we show that CD4+PF+ T cell expansions appeared to be strongly associated with CMV seropositivity in healthy individuals, and, particularly, in B-CLL patients. The immunocompromised status of the majority of B-CLL patients may facilitate expansion of this unusual population of cytotoxic cells to combat reactivation of a chronic CMV infection