Two-colour flow-cytometric analysis of pulmonary alveolar macrophages from smokers

T. Umino, C. M. Sköld, S. J. Pirruccello, J. R. Spurzem, S. I. Rennard

Research output: Contribution to journalArticlepeer-review

25 Scopus citations


The study of alveolar macrophages (AM) from smokers by flow cytometry (FCM) has been limited by strong autofluorescence and the lack of reliable markers to identify macrophages. Crystal violet quenching was reported to be effective in reducing autofluorescence of AM. CD68 is a marker for macrophages in immunohistochemistry, but has been less useful in FCM because of poor surface expression. This study evaluated the effectiveness of a method for two-colour FCM analysis of AM combined with membrane permeabilization and crystal violet quenching. Bronchoalveolar lavage cells, fixed in 4% paraformaldehyde and permeabilized using 0.5% Triton X100, were incubated with fluorescent-labelled antibodies for 30 min and quenched with a saturated crystal violet solution. Two-colour FCM was then performed using forward/side scatter gating to select AM. Autofluorescence at 525 nm (fluorescein isothiocyanate) and 575 nm (phycoerythrin) markedly decreased after quenching. After permeabilization, 97.1±2.8% of the gated cells were CD68+, while 53.9±18.6% of the AM were positive without permeabilization. CD68+ cells were sorted and proved to be AM morphologically. Analysis of CD71 (transferrin receptor) expression by FCM correlated with immunocytochemistry (r=0.77, p<0.05). The permeabilization/quenching technique, therefore, represents a satisfactory means to evaluate alveolar macrophages by flow cytometry.

Original languageEnglish (US)
Pages (from-to)894-899
Number of pages6
JournalEuropean Respiratory Journal
Issue number4
StatePublished - 1999


  • Bronchoalveolar lavage
  • CD68
  • Flow cytometry
  • Macrophages
  • Smoking

ASJC Scopus subject areas

  • Pulmonary and Respiratory Medicine


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