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In 10 of 14 patients with an active cytomegalovirus (CMV) infection, distinctive large cells (35-45 microns in diameter) were present in the peripheral blood. Morphologically these cells closely resembled the classic cytomegalic inclusion cells, generally regarded as a diagnostic hallmark of CMV infection. Moreover, these cells were shown to express CMV antigens belonging to all three stages of the viral replication cycle, indicating a productive CMV infection. In addition, immunologic staining with monoclonal antibodies directed against cell differentiation and marker proteins showed that these circulating cytomegalic cells were of endothelial origin. The presence of CMV-infected endothelial cells in the peripheral blood of patients with an active CMV infection indicates that such an infection might be accompanied by widespread occult vascular damage.

We describe enhanced expression and enzymatic activity of ecto-ATPase and ecto-5' nucleotidase on CMV infected endothelial cells as compared to uninfected cells, These ectoenzymes play a major role in modulation of platelet activation and aggregation. Furthermore, adenosine has a modulatory effect upon inflammation. Addition of ATP, ADP or AMP to cultures of CMV infected or uninfected endothelial cells revealed increased turnover of AMP in CMV infected endothelial cells. in addition, the superoxide production by stimulated polymorphonuclear cells was inhibited in the presence of CMV infected endothelial cells as compared to uninfected cells, probably due to the enhanced activity of ecto-5'-nucleotidase and associated to production of adenosine. (C) 2001 Federation of European Biochemical Societies. Published by Elsevier Science B.V. All rights reserved.