The evidence of human herpesvirus 6 infection in the lymph nodes of Hodgkin's disease.

Human herpesvirus 6 (HHV-6), the causative agent of exanthem subitum, has been implicated in other diseases. Recently HHV-6-specific sequences have been detected by Southern blot analysis and polymerase chain reaction in the lymph nodes of three patients with Hodgkin's disease. The pathological localization of HHV-6, however, is still unknown. In order to study the pathological role of HHV-6 in Hodgkin's disease, we investigated, by immunohistochemical and molecular methods, two lymph node biopsies taken from a 7-year-old boy with Hodgkin's disease during the course of disease evolution. Although the histopathological findings of the first biopsy differed from those of the second, HHV-6 antigens and sequences could be detected in both lymph nodes by immunohistochemistry and in situ hybridization, respectively. HHV-6 was localized in macrophages, predominantly in lymphoid follicles, but not in Reed-Sternberg cells. Antibody titres to HHV-6 were consistent with reactivation of latency. Neither cytomegalovirus nor Epstein-Barr virus was present. Our data suggest a role for HHV-6 in the pathogenesis of Hodgkin's disease.