Diagnostic value of CD103 expression in bronchoalveolar lymphocytes in sarcoidosis

Summary Background Pulmonary sarcoidosis is frequently characterized by a CD4+ /CD8+ ratio ≥3.5 in bronchoalveolar lavage fluid (BALF), although up to 40% of the cases present a normal or even decreased ratio, pointing out its variability and limitation as a diagnostic marker for sarcoidosis. Lung lymphocytes within the bronchial epithelium, the alveolar walls, and BALF express the integrin CD103. Our aim was to compare the expression of CD103 in BALF T-lymphocytes between sarcoidosis and other interstitial lung diseases (ILD) and to evaluate its relevance as a BALF diagnostic marker for sarcoidosis. Methods A total of 86 patients with ILD (mean age ± standard deviation, 42.6 ± 16.6 years; 60.5% female), who underwent BALF as part of their initial diagnostic work-up, were enrolled into 2 groups: sarcoidosis ( n = 41) and other ILD ( n = 45). Area under the receiver operating characteristic (ROC) curve (AUC) was used to describe the performance of CD103 for sarcoidosis diagnosis. Results Sarcoidosis patients presented a significantly reduced CD103 expression in BALF T-lymphocytes, more pronounced in the CD4+ subset. The BALF CD103+ CD4+ /CD4+ ratio for a cutoff point of 0.45 was associated with a better diagnostic performance for sarcoidosis (AUC: 0.86 [95% confidence interval (95% CI): 0.78–0.94]; sensitivity: 81%; specificity: 78%), even for those with a CD4+ /CD8+ ratio