Activated CD8(+) T cells and NKT cells in BAL fluid improve diagnostic accuracy in sarcoidosis

The clinical diagnosis of pulmonary sarcoidosis is based on the presence of noncaseating granulomas in an appropriate clinical setting with either bilateral hilar adenopathy and/or parenchymal infiltrates. Lymphocytosis with an increased CD4/CD8 T cell ratio in bronchoalveolar lavage fluid is supportive. We evaluated the diagnostic accuracy of a predictive binary logistic regression model in sarcoidosis based on sex, age, and bronchoalveolar lavage fluid cell profile with and without the inclusion of HLA-DR(+) CD8(+) T cells and natural killer T-cell fractions.

A retrospective analysis of differential cell counts and lymphocyte phenotypes by flow cytometry in bronchoalveolar lavage was performed in 183 patients investigated for possible diffuse parenchymal lung disease. A logistic regression model with age, sex, lymphocyte fraction, eosinophils, and CD4/CD8 ratio in bronchoalveolar lavage fluid (basic model) was compared with a final model, which also included fractions of HLA-DR(+) CD8(+) T cells and natural killer T cells. Diagnostic accuracy of the two models was assessed by receiver operating characteristic (ROC) curves.

The area under the ROC curve for the basic and final model was 0.898 [95 % confidence interval (CI) 0.852-0.945] and 0.937 (95 % CI 0.902-0.972), respectively, p = 0.008.

Assessment of HLA-DR(+) CD8(+) T cell and natural killer T-cell fractions may improve diagnostic accuracy and further strengthen the importance of bronchoalveolar lavage in the diagnostic workup of sarcoidosis.