Bronchoalveolar lavage cell composition in allogeneic bone marrow transplant patients without symptomatic lung complications.

The purpose of this study was to assess the cytological composition of bronchoalveolar lavage (BAL) fluid in allogeneic BMT patients without lung complications and compare it with that obtained from healthy volunteers. During the first 6 months post-BMT we studied the differential cell counts of 98 BALs from 56 patients as well as the total cell count of 44 BALs from 27 patients. The BAL cellular composition in BMT patients was clearly different from that of healthy subjects: there was a marked increase in alveolar neutrophils (in 82% of the patients when sequential BALs were performed) and an increase in lymphocytes, with a lower percentage of macrophages and similar numbers of eosinophils. A greater variation in cellular populations was found without an evident cause. The total number of cells per ml of fluid recovered appeared similar to that of healthy volunteers. A high frequency of neutrophilic alveolitis was found in patients with asymptomatic CMV on BAL. Owing to the variability of BAL cellular composition in asymptomatic BMT patients and its difference from that in healthy volunteers, great caution should be taken when interpreting the BAL composition data from patients with lung complications. In order to avoid drawing wrong conclusions these data should be compared with those obtained from a control group of BMT patients without lung complications and not from healthy volunteers.