Is persistent polyclonal b lymphocytosis caused by epstein‐barr virus? A study with polymerase chain reaction and in situ hybridization

Previous reports of patients with persistent polyclonal B lymphocytosis have found associations with female sex, cigarette smoking, HLA‐DR7 phenotype, and moderate elevation of peripheral blood polyclonal B lymphocytes. The presence of binucleated cells and atypical lymphocytes in the peripheral blood of these patients was highly suggestive of a viral infection, such as with the Epstein‐Barr virus. We report a 47‐year‐old asymptomatic woman who was incidentally found to have persistent polyclonal B lymphocytosis and serum IgG against virus capsid antigen (VCA) and Epstein‐Barr virus (EBV)‐associated nuclear antigen (EBNA) of EBV. The presence of EBV was investigated in the peripheral blood lymphocytes from this patient by in situ hybridization and polymerase chain reaction methods. EBV DNA was demonstrated in the lympohcyte fraction by polymerase chain reaction, and it was further located in lymphoid cells by in situ hybridization. These results indicate that persistent polyclonal B lymphocytosis is strongly associated with EBV. © 1992 Wiley‐Liss, Inc.