THE INVESTIGATION OF EPSTEIN-BARR VIRAL SEQUENCES IN 41 CASES OF BURKITTS-LYMPHOMA FROM EGYPT - EPIDEMIOLOGIC CORRELATIONS

Background. Epstein-Barr virus (EBV) is associated with many human neo plasms, including Burkitt's lymphoma (BL). Endemic BL in central Afric a is more often EBV-associated than BL in the United States, where ser oconversion for EBV occurs somewhat later than in Africa. Therefore, t he EBV association rate in BL may correlate more with the socioeconomi c status of the population studied, which influences the age of EBV se roconversion, than with such factors as malaria, which may relate to t he overall higher incidence rate in endemic regions. Methods. Forty-on e patients with BL in Egypt, which differs both climatically and racia lly from central African countries (i.e., Kenya, Uganda) where BL is e ndemic, were analyzed. All biopsies were evaluated for EBV-encoded RNA s (EBER1) by RNA in situ hybridization, analyzed for p53 protein expre ssion using the monoclonal antibody D07, and immunophenotyped using a panel of monoclonal antibodies that included L26 (CD20), Leu 22 (CD43) , and A6 (CD45RO). Twelve cases were evaluable for EBV subtype by poly merase chain reaction with EBV-specific primers. Results. The median a ge at diagnosis was 9 years (range, 2-22 years). The biopsy site was e xtranodal in 29 patients and nodal in 12 patients. All 41 cases were d ocumented as B-cell neoplasms. A hybridization signal for EBER1 RNA wa s identified in greater than 95% of the neoplastic cells in 30 of 41 c ases (73%), whereas no signal was observed in 11 cases (27%). Epstein- Barr virus subtype 1 was found in 10 patients, subtype 2 in two patien ts. Immunostaining for p53 was observed in greater than 5% of the neop lastic cells in 9 of 37 cases (24%). No significant correlation was ob served between EBV positivity and sex, biopsy site, or p53 immunostain ing. Conclusions. The prevalence of EBV in BL from Egypt is slightly l ower than in BL in endemic regions, but significantly higher than in s poradic BL. Epstein-Barr virus positivity probably reflects the socioe conomic status of the patient population, and age at seroconversion. T he prevalence of EBV subtype 1 suggests that immunodeficiency does not play a role in Egyptian Burkitt's lymphoma, in contrast to endemic Bu rkitt's lymphoma, in which holoendemic malaria is thought to contribut e to immunodeficiency, a higher incidence rate, and the observed preva lence of subtype 2.