Detection of CMV-matrix pp65 antigen in leucocytes by immunofluorescence as a marker of CMV disease.

The finding that active cytomegalovirus (CMV) infection is associated with an increased mortality after organ transplantation and the introduction of successful antiviral treatment render more urgent the development of rapid and accurate diagnostic methods. Rapid immunodiagnosis of active CMV infection was investigated by means of immunofluorescence staining of leucocytes by monoclonal antibodies. Monoclonals directed against the matrix protein, pp65, and ClonabR monoclonal antibody, which has been claimed to be directed against immediate early antigens, were used. All monoclonal antibodies directed against the matrix protein reacted equally well in staining of polymorphonuclear cells. Monoclonals described by Gerna et al. [1991] and by Pereira et al. [1982] also reacted more clearly with mononuclear cells. One hundred fifty heparinized blood samples were collected monthly from 82 patients within 3 months after transplantation. In addition, 132 EDTA blood samples were tested in connection with suspected CMV infection. The latter approach gave a better agreement between antigen detection and virus isolation. There was a relationship between active CMV infection and the finding of antigen-positive leucocytes (P = 0.002, Fisher's exact test) found within 1 month of one another. When the number of antigen-positive cells was taken into account, a relationship to severe CMV disease was detected (P < 0.001, Fisher's exact test). The antigen test was positive at an early stage during the development of severe CMV disease. This rapid method is useful for following the disease process of CMV and in determining when to initiate antiviral treatment.