Epstein-Barr virus and regulatory T cells in Egyptian paediatric patients with acute B lymphoblastic leukaemia

Objective Acute B lymphoblastic leukaemia (B-ALL) is the most common type of childhood malignancy worldwide but little is known of its origin. Recently, many studies showed both a high incidence of EpsteinBarr virus (EBV) infection and high levels of CD4(+)CD25(+) Foxp3(+)(Treg cells) in children with B-ALL. In our study, we investigated the possible relationship between EBV infection and the onset of B-ALL, and its relation to expression of CD4(+), CD25(high+) Foxp3+ T regulatory cells. Subject and methods We analysed expression and mean fluorescence intensity (MFI) of Treg cells in peripheral blood of 45 children with B-ALL and in 40 apparently healthy children as a control, using flow cytometry. Serum anti-EBV viral capsid antigen (VCA) IgG, anti-EBV nuclear antigen (EBNA) IgG (for latent infection) and anti-EBV VCA IgM (for acute infection) were investigated using ELISA. Results Analysis of the Treg cells population in patients and controls revealed that expression of CD4(+) CD25(high+) T lymphocytes was higher in patients than in controls (mean +/- SD 15.7 +/- 4.1 and 10.61 +/- 2.6 in patients and controls, respectively, and MFI of Foxp3 was 30.1 +/- 7.1 and 16.7 +/- 3.7 in patients and controls, respectively (p<0.001)). There was a high incidence of latent EBV infection in patients (31%) compared with controls (10%) while the incidence of acute infection was 12% in patients and 0% in the control group. To study the role of latent EBV infection in the pathogenesis of acute B-ALL, OR was calculated (OR= 4.06, coefficient index 1.2-13.6). Conclusions These findings suggest a possible role for Treg cells and EBV in the pathogenesis of B-ALL. Further studies are needed on the possible mechanisms of tumour genesis related to Treg cells and EBV in children with B-ALL.