Detection of Epstein-Barr virus in lymphoid tissues of patients with infectious mononucleosis by in situ hybridization.

Although the immunological response during infectious mononucleosis (IMN) has been studied in detail, little is known about the spread of Epstein-Barr virus (EBV) in lymphoid organs or the topographical distribution of the infected cells. In this study, EBV was detected in 11 lymph nodes, 4 tonsils, and 1 spleen of 16 patients with IMN. The predominant cell type positive for the EBV genome was identified as small lymphocytes localized chiefly within typical T areas, preferentially in perifollicular and interfollicular regions of the lymph node. A few endothelia of epithelioid venules were also found to be positive. Furthermore, a small number of sinus lining cells of lymph nodes exhibited labelling. Altogether, only a small number of cells, not exceeding 1 per cent of all cells, were infected with EBV. Our results show that only a small number of lymphocytes carry the EBV and that besides B lymphocytes, other cell constituents of lymphatic tissues are infected by EBV during IMN.