[Evaluation of direct immunoperoxidase technique using F(ab')2 fractions of anti-cytomegalovirus human monoclonal antibody for enumeration of cytomegalovirus antigen-positive leukocytes].

Direct immunoperoxidase technique using human monoclonal antibody (C7) against a p65 antigen of cytomegalovirus (CMV) has been utilized to detect CMV antigen-positive leukocytes in the peripheral blood (CMV antigenemia). This technique was evaluated for enumeration of CMV antigen-positive leukocytes. The parameters included stability of the reagents, reproducibility of the results and quantitativity of the detection. The horseradish peroxidase (HRR)-labeled F(ab')2 fractions of C7 antibody were found to be superior to the equivalent Fab' fractions, because the former was much more stable than the latter. Enumeration of the CMV antigen-positive leukocytes were very reproducible and quantitative. The detection limit was one CMV antigen-positive cell per 50,000 leukocytes. Thus, this technique is reliable and practical to detect the CMV antigenemia, and it will contribute to early diagnosis of CMV diseases and initiation of antiviral therapy.