Epstein-Barr virus in Hodgkin's disease.

Hodgkin's disease (HD) represents a phenotypically and genotypically heterogeneous lymphoma of CD30-positive tumour cells. Infection of the tumour cells with Epstein-Barr virus (EBV) is found in significant proportions of cases with geographical variation and represents the most common genetic abnormality detectable in HD. If present, EBV is found in all tumour cells with an usually monoclonal composition of episomes, indicating that EBV infection occurs prior to clonal expansion of the tumour cells. Largely by the EBV-encoded protein LMP1, the virus may influence the expression of differentiation antigens and apoptosis. EBV-induced modulation of cytokine expression results in the activation of autocrine and paracrine regulatory loops and may contribute to the local inhibition of EBV-specific immunity observed in EBV-positive HD.