The nature and clinical significance of atypical mononuclear cells in infectious mononucleosis caused by the Epstein-Barr virus in children.

Atypical mononuclear cells (AM) appear in significant numbers in peripheral blood of patients with Epstein-Barr virus (EBV)-associated infectious mononucleosis (IM). We have investigated the number and lineage-specific clusters of differentiation (CD) expression of the atypical mononuclear cells in 110 children with IM using the anti-CD antibody microarray for panning the leukocytes by their surface markers prior to morphology examination. We show that AM population consists primarily of CD8+ T-cells with a small fraction (0-2% of all lymphocytes) of CD19+ B-lymphocytes. The AM amount in children with mononucleosis caused by primary EBV infection was significantly higher than for IM caused by EBV reactivation or other viruses and constituted 1-53% from all peripheral blood mononuclear cells compared to 0-11% and 0-8% respectively. The children failing to recover from classic IM associated with primary EBV infection in 6 months were found to have significantly lower percentage of CD8+ AM compared to the patients with normal recovery rate.