Comparison of the diagnostic value of different lymphocyte subpopulations in bronchoalveolar lavage fluid in patients with biopsy proven sarcoidosis

Bronchoalveolar lavage is considered a helpful tool in the diagnosis of diffuse parenchimal lung diseases such as sarcoidosis. CD4/CD8 ratio is higly specific but not sensitive to distinguish sarcoidosis and other intestitial lung diseases. We aimed to compare the diagnostic value of CD4/CD8 ratio and other lmphocyte subpopulations such as CD3+16+56, CD103+, CD4+CD103+, CD8+CD103+ in bronchoalveolar lavage to distinguish sarcoidosis and other nonsarcoidosis interstitial lung diseases. Using the bronchoscopy records from 2006 to 2013, we evaluated 68 patients with biopsy proven sarcoidosis and 72 patients with clinicoradiological and/or biopsy proven diffuse parenchimal lung diseases. Cut off values, sensitivity and specificity were given for aforementioned parameters. Bronchoalveolar lavage CD4/CD8 ratio, CD4+ T lymphocyte percentage, CD4+103+, CD3+CD103-, CD8+CD103+/CD103+ ratio were significantly higher in sarcoidosis than other diffuse parenchimal lung diseases whereas CD3+103+, CD3+16+56+, CD8+, CD8+CD103+, CD8+CD103+/CD8+ were significantly lower. Best cut off value of CD4/CD8 was 1.34 with sensitivity and specificity 76.4%, 79.4% respectively. The cut off values of CD4/CD8 of >3.5 and >2.5 had specificity 95.9% and 95.3%, respectively and sensitivity 52%, 41%, respectively. CD4/CD8 ratio is highly specific but not sensitive for sarcoidosis diagnosis. Thus, BAL flow cytometry is not diagnostic alone without appropriate clinicoradiological and/or histopathological findings.