Detection of human cytomegalovirus DNA from allogeneic bone marrow transplant recipients with interstitial pneumonitis

Interstitial pneumonitis (IP) due to human cytomegalovirus (HCMV) infection can kill patients who receive allogeneic bone marrow transplants (BMT), However, making a definitive diagnosis of HCMV-associated IP is difficult, except in pathologically defined cases, The authors tried to detect HCMV DNA amplified by the polymerase chain reaction with nonradioactive Southern blot analysis from paraffin-embedded lung tissue. Human cytomegalovirus DNA was detected in all of ten BMT recipients with IP and all of three non-BMT recipients with histologically diagnosed HCMV IP. Clinical diagnoses indicated that three of ten allogeneic BMT recipients had HCMV IP, and they showed amplified HCMV DNA despite the lack of histologic viral inclusions, However, HCMV DNA was not detected in 11 immunosuppressed patients with non-HCMV pneumonitis or in 10 patients without pneumonitis who were included as controls. These observations indicate that the polymerase chain reaction and Southern blot analysis used with lung tissue is more sensitive than histologic examination, and that these tests may be applicable to transbronchial lung biopsy specimens for the early specific diagnosis of HCMV IP. Further analysis of allogeneic BMT recipients showed that four patients who died of HCMV IP fewer than 90 days after BMT had higher quantities of HCMV DNA, whereas six patients who died of HCMV IP more than 90 days after BMT showed lower quantities of HCMV DNA. This result suggests that HCMV IP in the late phase after BMT might not be attributable to active virus replication alone but rather to the immune response involved in the graft-versus-host reaction.