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Bronchoalveolar lavage cell populations in the diagnosis of sarcoidosis
R H Winterbauer1, J Lammert, M Selland
1Section of Pulmonary and Critical Care Medicine, Virginia Mason Clinic, Seattle 98101.
Insights
Bronchoalveolar lavage (BAL) cell analysis, particularly CD4/CD8 ratios and neutrophil/eosinophil percentages, aids in diagnosing sarcoidosis. Combining BAL findings with transbronchial biopsy (Tbbx) improves diagnostic accuracy for sarcoidosis.
Area of Science:
- Pulmonology
- Immunology
- Diagnostic Medicine
Background:
- Interstitial lung diseases (ILDs) present diagnostic challenges.
- Bronchoalveolar lavage (BAL) and transbronchial biopsy (Tbbx) are key diagnostic tools.
- Identifying specific biomarkers in BAL fluid can improve sarcoidosis diagnosis.
Purpose of the Study:
- To evaluate the diagnostic utility of BAL fluid cell differentials and CD4/CD8 ratios in distinguishing sarcoidosis from other lung conditions.
- To compare the diagnostic accuracy of BAL findings with traditional Tbbx for sarcoidosis.
Main Methods:
- Fiberoptic bronchoscopy and BAL were performed on 2,692 patients.
- 128 patients with >=16% lymphocytes in BAL fluid were analyzed.
- BAL cell percentages (lymphocytes, neutrophils, eosinophils) and CD4/CD8 ratios were assessed.
- Results were compared to Tbbx findings, including multiple noncaseating granuloma (MNG).
Main Results:
- Lymphocyte percentages alone did not differentiate sarcoidosis.
- Sarcoidosis patients showed higher CD4/CD8 ratios and lower neutrophils/eosinophils in BAL.
- A BAL CD4/CD8 ratio >= 4:1 had 94% positive predictive value for sarcoidosis vs. ILD.
- A BAL CD4/CD8 ratio < 1:1 had 100% negative predictive value for sarcoidosis.
- Low neutrophil percentages in BAL also showed diagnostic value.
Conclusions:
- BAL fluid analysis (CD4/CD8 ratio, neutrophils, eosinophils) shows promise for sarcoidosis diagnosis.
- Combining BAL findings with Tbbx (MNG) significantly enhances diagnostic accuracy.
- Specific BAL criteria (CD4/CD8 >= 2:1, low neutrophils/eosinophils) combined with MNG on Tbbx achieved 93% accuracy.
Study Design:
Between February 1, 1984, and February 1, 1989, fiberoptic bronchoscopy was performed on 2,692 patients, 592 of whom had bronchoalveolar lavage (BAL). One hundred twenty-eight patients with 16 percent or more lymphocytes in BAL fluid (BALF) were selected for further study. The group included 27 patients with sarcoidosis, 28 with nonsarcoidosis interstitial lung disease (ILD), 22 with lung infection (organism isolated), 31 with inflammation (presumed infection, no organism isolated), 14 with neoplasm, and 6 with bronchial hyperreactivity.
Methods:
The percentages of lymphocytes, B lymphocytes, and T lymphocytes, the CD4/CD8 ratio and the percentages of neutrophils and eosinophils were analyzed individually and in combination for discrimination between the sarcoidosis and nonsarcoidosis patients and compared with the diagnostic accuracy of multiple noncaseating granuloma (MNG) on a simultaneous transbronchial biopsy (Tbbx).
Results:
Neither the percentages of lymphocytes, T lymphocytes, or B lymphocytes discriminated sarcoidosis from nonsarcoidosis patients. Sarcoidosis patients had higher CD4/CD8 ratios, fewer neutrophils, and 1 percent or less eosinophils in the BAL cell populations. An analysis of CD4/CD8 ratios, and percentages of neutrophils and eosinophils individually revealed that a CD4/CD8 ratio of 4:1 or greater had a positive predictive value of 94 percent in distinguishing sarcoidosis from other ILD but a sensitivity of only 59 percent. The positive predictive value of CD4/CD8 ratio of 4:1 or greater fell to 50 percent in separating sarcoidosis from all other diseases. A CD4/CD8 ratio of less than 1:1 has a 100 percent negative predictive value to exclude the diagnosis of sarcoidosis. Finding 1 percent or less neutrophils in BAL had an 80 percent positive predictive value in distinguishing sarcoidosis from nonsarcoidosis ILD and 51 percent for distinguishing sarcoidosis from all other disease groups. The CD4/CD8 ratio and the percentages of neutrophils and eosinophils also were combined and analyzed for the diagnosis of sarcoidosis.
Conclusions:
Results showed a BALF with a CD4/CD8 ratio of 2:1 or greater, 1 percent or less neutrophils, and 1 percent or less eosinophils has essentially the same specificity and positive predictive value as MNG on Tbbx in distinguishing sarcoidosis from nonsarcoidosis disease. The combination of finding MNG in a Tbbx specimen plus a BALF CD4/CD8 ratio of 4:1 or greater had a 100 percent positive predictive value in separating sarcoidosis from other ILD and an 81 percent value in separating sarcoidosis from all other disease. Finding MNG in a Tbbx specimen plus a BALF with a CD4/CD8 ratio of 2:1 or greater, 1 percent or less neutrophils, and 1 percent or less eosinophils had a 93 percent positive predictive value in distinguishing sarcoidosis from both nonsarcoidosis ILD and all other diseases.