CHRONIC PERSISTENT EPSTEIN-BARR-VIRUS INFECTION OF NATURAL-KILLER-CELLS AND B-CELLS ASSOCIATED WITH GRANULAR LYMPHOCYTES EXPANSION

B lymphocytes and epithelial cells are the only cell types known to be infected with Epstein-Barr virus (EBV) in normal individuals. Rarely, EBV also infects other cells, including natural killer (NK) cells, al most always in the contest of fatal leukaemias or lymphoproliferative disorders, We report on a 6-year-old previously healthy girl who devel oped fevers and liver function abnormalities for 3 months. The periphe ral blood revealed an abnormal expansion of large granular lymphocytes , comprising 24% of the white blood cells. Flow cytometric analysis of the peripheral blood mononuclear cells showed an abnormal increase of CD16-positive NK cells, 62% of which were EBV-infected by in situ EBE R-1 hybridization. The circulating B cells were normal in number, but 18% were infected with EBV by in situ EBER-1 hybridization. Approximat ely 2 years after resolution of all symptoms and continued good health , 35% of the circulating mononuclear cells were EBV-infected, indicati ve of persistent expansion of EBV-infected cells. We conclude that abn ormal expansions of EBV-infected NK and B cells can be associated with a chronic benign course.