Cytomegalovirus Infection of the Human Placenta: An lmmunocytochemical
Study
KATHRIN MUHLEMANN, MD, RICHARD K. MILLER, PHD, LEON METLAY, MD, AND MARILYN A. MENEGUS, PHD In congenital
cytomegalovirus
(CMV) infection histologic
evaluation
of the placenta is often unrevealing. In the present study immunocytochemistry to CMV immediate early and early nuclear antigens was used to characterize placental involvement in six cases of symp tomatic intrauterine CMV infection. Histologic examination had demonstrated diagnostic viral inclusions in one placenta and nonspecific villitis in another. However, immunocytochemistry revealed CMV infection in five of the six placentas, including three with no pathologic changes on routine histologic evaluation. Infected cells were located primarily in the villous stroma. In one case immunoperoxidase staining showed infection in the syncytiotrophoblast. Infected endothelial cells were demonstrated by double staining for CMV and factor VIII antigen. No double-stained cells were seen in tissue sections stained for CMV immediate early nuclear antigen or the human macrophage-associated CD68 antigen, which is expressed in Hofbauer cells. In conclusion, specific immunoperoxidase staining was more sensitive for demonstrating placental CMV infection than was histologic examination and it aided in the characterization of infected cells. HUM PATHOL 23:1234-1237. Copyright 0 1992 by W.B. Saunders Company Cytomegalovirus (CMV) is the most common cause of intrauterine infection in humans. In the United States, 1% of all live-born infants are congenitally infected, of whom at least 15% have signs and symptoms of infection at birth or later in life.’ It is generally assumed that intrauterine transmission occurs transplacentally during maternal viremia. If this is true the placenta acts as a portal of entry for the virus, but it also must act as a barrier because even during primary maternal infection, transmission occurs in only 40% of cases. Despite its important role very little is known about the interaction between CMV and the placenta. Sensitive and specific methods are now available for the demonstration of CMV in infected tissue. Monoclonal antibodies to CMV antigens make immunocytochemistry a potentially useful tool. McCaffree and Altshuler’ first suggested the use of indirect immunofluorescence to confirm the CMV etiology of suspicious From the Departments of Obsretrics/Gynecolo~, Environmental Health Science Center, Microbiology and Immunology, Pathology and Laboratory Medicine, and Pediatrics, University of Rochester, Rochester. NY: and the Institute of Medical Microhiolou, University of Berne, Berne, Switzerland. Accepted for publication January 20. 1992. Supported in part by the Swiss National Foundation and National Institutes of Health grant no. ES0 2774. Kq words: cytomegalovirus, Hofbauer cells. placenta. trophoblast. Address correspondence and reprint requests to Kathrin Miihlemann, MD, Department of Epidemiology, 5X-36. School of Public Health, University of Washington. Seattle. WA 98195. Copyright 0 1992 by W.B. Saunders Compaq 0046-8177,‘92/231 l-OOOS$S.OO/O
1234
placental lesions. The detection and localization of CMV-infected cells by an even more sensitive and specific means was reported recently by Toorkey and Carrigan.” These investigators specifically identified CMV-infected cells by double staining with monoclonal antibodies to both cell markers and CMV. These techniques open the door to the study of the interaction between CMV and the placenta in greater detail than was possible by conventional histology. In this study placentas from congenitally infected infants were retrospectively examined using single- and double-staining itnmunocytochemistry to search for placental CMV infection and to characterise infected cells. MATERIALS
AND METHODS
(&es of‘ congenital (:hl\’ inftctiorr werr identified r.rtrospectivel! through the records of clinical nricrohiolob~ arrd histopatholob~ laboratories. A case was included in the stud! if (I )
Study
KATHRIN MUHLEMANN, MD, RICHARD K. MILLER, PHD, LEON METLAY, MD, AND MARILYN A. MENEGUS, PHD In congenital
cytomegalovirus
(CMV) infection histologic
evaluation
of the placenta is often unrevealing. In the present study immunocytochemistry to CMV immediate early and early nuclear antigens was used to characterize placental involvement in six cases of symp tomatic intrauterine CMV infection. Histologic examination had demonstrated diagnostic viral inclusions in one placenta and nonspecific villitis in another. However, immunocytochemistry revealed CMV infection in five of the six placentas, including three with no pathologic changes on routine histologic evaluation. Infected cells were located primarily in the villous stroma. In one case immunoperoxidase staining showed infection in the syncytiotrophoblast. Infected endothelial cells were demonstrated by double staining for CMV and factor VIII antigen. No double-stained cells were seen in tissue sections stained for CMV immediate early nuclear antigen or the human macrophage-associated CD68 antigen, which is expressed in Hofbauer cells. In conclusion, specific immunoperoxidase staining was more sensitive for demonstrating placental CMV infection than was histologic examination and it aided in the characterization of infected cells. HUM PATHOL 23:1234-1237. Copyright 0 1992 by W.B. Saunders Company Cytomegalovirus (CMV) is the most common cause of intrauterine infection in humans. In the United States, 1% of all live-born infants are congenitally infected, of whom at least 15% have signs and symptoms of infection at birth or later in life.’ It is generally assumed that intrauterine transmission occurs transplacentally during maternal viremia. If this is true the placenta acts as a portal of entry for the virus, but it also must act as a barrier because even during primary maternal infection, transmission occurs in only 40% of cases. Despite its important role very little is known about the interaction between CMV and the placenta. Sensitive and specific methods are now available for the demonstration of CMV in infected tissue. Monoclonal antibodies to CMV antigens make immunocytochemistry a potentially useful tool. McCaffree and Altshuler’ first suggested the use of indirect immunofluorescence to confirm the CMV etiology of suspicious From the Departments of Obsretrics/Gynecolo~, Environmental Health Science Center, Microbiology and Immunology, Pathology and Laboratory Medicine, and Pediatrics, University of Rochester, Rochester. NY: and the Institute of Medical Microhiolou, University of Berne, Berne, Switzerland. Accepted for publication January 20. 1992. Supported in part by the Swiss National Foundation and National Institutes of Health grant no. ES0 2774. Kq words: cytomegalovirus, Hofbauer cells. placenta. trophoblast. Address correspondence and reprint requests to Kathrin Miihlemann, MD, Department of Epidemiology, 5X-36. School of Public Health, University of Washington. Seattle. WA 98195. Copyright 0 1992 by W.B. Saunders Compaq 0046-8177,‘92/231 l-OOOS$S.OO/O
1234
placental lesions. The detection and localization of CMV-infected cells by an even more sensitive and specific means was reported recently by Toorkey and Carrigan.” These investigators specifically identified CMV-infected cells by double staining with monoclonal antibodies to both cell markers and CMV. These techniques open the door to the study of the interaction between CMV and the placenta in greater detail than was possible by conventional histology. In this study placentas from congenitally infected infants were retrospectively examined using single- and double-staining itnmunocytochemistry to search for placental CMV infection and to characterise infected cells. MATERIALS
AND METHODS
(&es of‘ congenital (:hl\’ inftctiorr werr identified r.rtrospectivel! through the records of clinical nricrohiolob~ arrd histopatholob~ laboratories. A case was included in the stud! if (I )
