Search

Dual exposure to Epstein-Barr virus and purified 4-deoxyphorbol ester derived from the plant Euphorbia tirucalli induced a high frequency of chromosomal rearrangements in human B lymphocytes in vitro. Rearrangements most commonly affected chromosome 8, the chromosome most often showing structural changes in Burkitt's lymphoma (BL) cells. E tirucalli is indigenous in parts of Africa where BL is endemic and may be an important risk factor for the disease.

Five cases of lethal midline granuloma were identified histologically and phenotypically as peripheral T-cell lymphomas. Epstein-Barr virus (EBV) DNA was detected in the nasal tumour biopsy specimens by Southern blotting and in-vitro hybridisation with simultaneous detection of EBV-determined nuclear antigen (EBNA) and T-cell surface markers by two-colour immunofluorescence. Further immunofluorescence and northern blotting revealed that EBNA2 gene and also latent membrane protein gene were expressed in the nasal tumour cells. The patients had high titres of antibodies to EBV. These findings suggest that lethal midline granuloma is causally associated with EBV.

A monoclonal malignant lymphoma was diagnosed in a 30-month-old Japanese boy, who, since the age of 12 months, had had chronic, recurrent infectious mononucleosis manifested by repeated episodes of severe cough and high fever accompanied by marked lymphadenopathy and hepatosplenomegaly and high serum Epstein-Barr virus (EBV) antibody titres. The diagnosis of Burkitt's lymphoma was made when a cervical lymph-node biopsy specimen revealed massive proliferation of immature B-cells with starry-sky histiocytes. These lymph-node cells were characterised by a translocation between chromosomes 10 and 17. There were approximately 9 EBV genome-equivalents per cell. Most cells were positive for nuclear antigen (EBNA); early antigen (EA) and viral capsid antigen (VCA) were also detected. The presence of EBV was supported by finding that the cell-free lymph-node extract transformed cord-blood lymphocytes into EBNA-positive blast cells. The proportion of EA-positive and VCA-positive cells increased rapidly in culture for 24 h, then the positive cells degenerated rapidly and completely. The cells also contained numerous herpes-type virus particles. The child improved considerably with cytostatic treatment and has been in remission for 2 years.