Tehran University of Medical Sciences Acta Medica Iranica 0044-6025 40 1 2002 03 15 6 10 Mansoori SD Shahgasempour S 2015 09 28 The immune responses that develop following Epstien-Barr Virus (EBV) infection are complex and involve both humoral and to a greater extent cell-mediated immune mechanisms. To evaluate the immune response, flow cytometric analysis of the peripheral blood of six patients during the acute phase of EBV infection was performed. This analysis revealed a significant increase in the percentages and the absolute number of CD8+cytotoxic and activated (HLA-DR+ - T lymphocytes and in some cases with a concomitan decrease in the percentages of B (CD19+) lymphocytes and T helper (CD4+) lymphocytes. These patient invariably had inverted CD4/CD8 ratio. All changes reversed to normal level during the recovery phase of infection. It is therefore concluded that EBV specific cytotoxic and activated T lymphocytes are essential in controlling acute EBV infection presented by the infected B cells. https://acta.tums.ac.ir/index.php/acta/article/view/2539 https://acta.tums.ac.ir/index.php/acta/article/download/2539/2526