Flow cytometric detection of cytomegalovirus antigen in peripheral blood cells after bone marrow transplantation

Cytomegalovirus (CMV) immediate-early (IE) antigen within the nucleus of cells was detected by flow cytometry in peripheral blood obtained from five bone marrow transplant recipients. In patients with an unexplained fever, CMV antigens were detected in monocytes or lymphocytes. On the other hand, in patients with CMV pneumonia, CMV antigens were detected in polymorphonuclear leucocytes (PMNLs). We suggest that the detection of CMV antigen in monocytes or lymphocytes may be related to CMV activation or reactivation, and the positive results in PMNLs indicate that the patient has a CMV-associated disease (CMV pneumonia). Our method may be useful in monitoring CMV activation or reactivation, and analysing the mechanisms of CMV infection.