Objective: To test the hypothesis whether PMN-Elastase in bronchoalveolar lavage fluid (BALF) could reflect neutrophil activity in the lower respiratory tract.
Design: Prospectively, morphologic findings of acute and chronic inflammation in the transbronchial lung biopsy specimens were compared with the numbers of neutrophils in the BALF and the concentration of PMN-Elastase in the same.
Setting: Ambulatory outpatient service of bronchology and respiratory physiopathology and intensive care unit of a communal hospital.
Patients: 50 ambulatory outpatients and 10 critically ill patients of the ICU, presenting infiltrative lung diseases.
Interventions: Transbronchial lung biopsies and bronchoalveolar lavage were performed through a fiberoptic bronchoscope. Venous blood samples were obtained after bronchoscopy.
Measurements and results: Biopsy specimens and cell count in the BALF were examined by light microscopy. PMN-Elastase and albumin were measured in the BALF-supernatant and in the plasma. C-reactive protein (CRP) and a1 proteinase inhibitor (a1-PI) were measured in the plasma. Intrapulmonary originating PMN-Elastase was calculated with reference to albumin. The results concerning acute inflammation obtained by transbronchial lung biopsy (TBLB) (n = 16) correlated better with the levels of PMN-Elastase in the BALF (n = 21) than with the neutrophil count (n = 28) (p < 0.5 versus p < 0.025 for chi 2). The sensitivities and specificities of the above methods were respectively 76.9%, 100%, 100% and 100%, 95.2%, 63.1%. The intrapulmonary originating PMN-Elastase was about 99.7% of the measured BALF-Elastase.
Conclusion: The PMN-Elastase concentration in the BALF is a more accurate indicator of the inflammatory intensity in the alveolar structures than in the number of neutrophils. It may therefore be useful to the clinician in his attempt to detect acute inflammation in the lower respiratory tract.