[Monitoring of Epstein-Barr virus-infected cells by flow cytometer permits early diagnosis and evaluation of disease progression in EBV-associated hemophagocytic lymphohistiocytosis].

Epstein-Barr virus-associated hemophagocytic lymphohistiocytosis (EBV-HLH) is characterized by clonal expansion of EBV-infected CD8(+)T-cells. We have recently demonstrated that detection of a clonally expanded population of EBV-infected CD8(+)T-cells with CD5 down-regulation was a useful tool to distinguish EBV-HLH from EBV-related disorders such as severe infectious mononucleosis. A 5-year-old girl who presented with fever, pancytopenia and liver dysfunction was diagnosed by this method in addition to conventional diagnostic tests. Further, EBV-infected cells were identified as CD5(-)HLA-DR(+) TCR V β3(+) CD8(+)T cells, an increase or decrease of which over time reflected the disease severity in this patient. Treatment of patients with EBV-HLH varies from steroid alone to intensive chemotherapy or hematopoietic stem cell transplantation. Easy monitoring of EBV-infected cells by using flow cytometry over time may provide useful information to choose an appropriate treatment for each individual patient with EBV-HLH.