Immunohistochemical study on the infection of herpes simplex virus, human cytomegalovirus, and Epstein-Barr virus in secondary diffuse interstitial pneumonia

We examined the infection of herpes simples virus (HSV), human cytomegalovirus (HCMV), and Epstein-Barr virus (EBV) in 61 autopsy cases with secondary diffuse interstitial pneumonia (SDIP) by immunohistochemistry and compared our findings with those in 46 individuals without lung complications. There was no significant difference in positivity of HSV infection between SDIP cases (28 of 61; 45.9%) and the controls (24 of 46; 52.2%). However, HSV was more extensively distributed in the lungs of seven SDIP cases than in those of controls and proliferated to form inclusion bodies in host cells of 11 SDIP cases. Twenty-two (36.1%) and 19 (31.1%) SDIP cases were positive for HCMV and EBV, respectively, whereas all the 46 controls were negative for both viruses. Eighteen of 22 HCMV-positive cases contained classical inclusion bodies in host cells. Epstein-Barr virus was detected extensively in the lungs of seven SDIP patients, but no viral inclusion bodies were observed in host cells. These findings indicate that the herpes viruses replicate excessively in a considerable number of SDIP cases, but classical inclusion bodies are not always associated with viral infection in the lungs. Major infected cells of these viruses were alveolar lining pneumocytes and intra-alveolar cells. Herpes simplex virus and EBV were detected in leukocytes as well as in pneumocytes. In addition, compared with HCMV and HSV, EBV frequently multiplied in bronchial or bronchiolar epithelial cells. Preferential host cells for these types of herpes virus were somewhat different from one another.