Role of Epstein-Barr virus in the etiology of Burkitt's lymphoma.

Although Epstein-Barr virus (EBV) was discovered in cultured Burkitt's lymphoma (BL) cells, its exact role remains unclear. Viral genome is found in 95-98% of endemic BL and 15-20% of non-endemic BL. Children destined to develop BL in Africa show elevated titres of viral capsid antibodies one to two years preceding emergence of BL. A multistep process follows early EBV infection during early childhood. Immune deficiency probably permits continuation of the infections, with smouldering polyclonal B-cell proliferation proceeding. Final steps in the pathogenesis consist of cytogenetic and molecular conversion to monoclonal BL. Reciprocal chromosomal translocations involve breakpoints containing c-myc, heavy- and light-chain Ig loci. Activation of oncogenes, c-myc and B-lym, may be essential in the molecular pathogenesis of BL. A spectrum of EBV-induced pathological entities is found in individuals with X-linked lymphoproliferative and acquired immune deficiency syndromes. Lymphoma identical to endemic BL occurs in these immune-deficient patients. Non-endemic BL is possibly due to immune defects, initiators and promoters of B-cell proliferation, which may not be identical to factors in endemic BL; however, cytogenetic events and activation of oncogenes may be pathways of both endemic and non-endemic BL.