Epstein-Barr virus-associated lymphomas

Abstract

Epstein-Barr virus (EBV), originally discovered through its association with Burkitt lymphoma, is now aetiologically linked to a remarkably wide range of lymphoproliferative lesions and malignant lymphomas of B-, T- and NK-cell origin. Some occur as rare accidents of virus persistence in the B lymphoid system, while others arise as a result of viral entry into unnatural target cells. The early finding that EBV is a potent B-cell growth transforming agent hinted at a simple oncogenic mechanism by which this virus could promote lymphomagenesis. In reality, the pathogenesis of EBV-associated lymphomas involves a complex interplay between different patterns of viral gene expression and cellular genetic changes. Here we review recent developments in our understanding of EBV-associated lymphomagenesis in both the immunocompetent and immunocompromised host.This article is part of the themed issue 'Human oncogenic viruses'.

Keywords: Burkitt lymphoma; Epstein–Barr virus; Hodgkin lymphoma; T/NK lymphoma; diffuse large B cell lymphoma; post-transplant lymphoproliferative disease.

Figure 1.

Germinal centre origin of different B cell lymphomas. Circulating naive B cells migrate to the secondary lymphoid organs where, upon encountering antigen, differentiate into centroblasts (CB) that undergo clonal expansion within the dark zone of the germinal centre. During proliferation, the process of somatic hypermutation (SHM) introduces point mutations into the variable region of the Ig heavy and light chain sequences, thereby generating B cells with variant B cell receptors (BCRs). Centroblasts subsequently differentiate into resting centrocytes (CC) and migrate to the light zone, where they are selected on the basis of antigen affinity. Only B cells with advantageous BCR mutations that improve antigen affinity will interact with follicular dendritic cells (FDCs) and receive the appropriate T cell survival signals necessary to evade apoptosis. Antigen-selected B cells can undergo further rounds of proliferation, mutation and selection by recycling to the dark zone. B cells within the light zone can undergo immunoglobulin class switch recombination (CSR), before exiting the germinal centre, either as a memory B cells or plasma cells. Due to the processes of SHM and CSR mediated by activation-induced cytidine deaminase (AID), germinal centre B cells are particularly susceptible to genetic damage. Thus, aberrant AID activity contributes to the chromosomal translocations and mutations that give rise to the different B lymphomas derived from B cells blocked at distinct stages of differentiation. PBL, plasmablastic lymphoma; PEL, primary effusion lymphoma.