Evaluation of HCMV on transbronchial biopsies in lung transplant recipients

Introduction. Human cytomegalovirus (HCMV) can cause direct and indirect effects in lung transplant recipients. Virological monitoring is usually performed by evaluation of viral load on bronchoalveolar lavage (BAL). However, few centers perform surveillance bronchoscopies with transbronchial biopsy (TBB) for investigating the occurrence of HCMV infection/disease, in addition to rejection. In this study, prevalence and clinical role of HCMV quantification on TBB have been studied. Methods. HCMV has been quantified by real-time PCR on 87 serial TBB specimens from 30 lung transplant recipients (all receiving anti-HCMV prophylaxis) and on the corresponding BAL and whole blood specimens. Results have been related to available histopathological features (including pneumonia, acute rejection, chronic rejection) and immunohistochemistry. Results. HCMV has been detected in 8%, 32.2%, and 16.7% of TBB, BAL, and whole blood specimens, respectively. Interstitial pneumonia has been diagnosed in 14.9% of cases, with a significant association to HCMV positivity on TBB (viral load 103-104 copies/104 cells), but not on BAL and whole blood. No significant association between HCMV positivity on TBB and acute or chronic rejection has been found, although previous episodes of HCMV pneumonia had occurred in two patients with chronic rejection. Conclusions. Evaluation of HCMV on TBB could be useful to identify episodes of local reactivation with subsequent organ disease. Although sampling errors on TBB must always be considered, this could allow to overcome problems in BAL dilution. Surveillance TBB in lung transplant recipients allows for early identification of rejection episodes or HCMV reactivation, thus suggesting the initiation of antiviral therapy and optimizing clinical management.