Integrin α E β 7 (CD103) expression in bronchoalveolar lymphocytes of patients with hypersensitivity pneumonitis.

Purpose: CD4+/CD8+ ratio in bronchoalveolar lavage fluid (BALF) often retrieves contradictory findings when used for diagnosis of sarcoidosis and hypersensitivity pneumonitis (HP), so CD103+ has been investigated as a possible differential marker. We aimed to compare CD103+ expression in BALF T-lymphocytes between patients with HP, sarcoidosis and other interstitial lung diseases (ILD).

Methods: An observational study carried out over a 2-year period included consecutive patients with suspected ILD who underwent BALF as part of their initial diagnostic work-up; CD103+ expression on BALF T-lymphocytes was evaluated. After a final diagnosis established according to international criteria, three patient subgroups-HP, ILD (which included idiopathic interstitial pneumonia and connective tissue disease-associated lung disorders) and sarcoidosis-were considered for further analysis.

Results: A total of 77 subjects were enrolled, 20 with HP, 16 with other ILD and 41 with sarcoidosis. A significantly higher number of CD4+ CD103+ and CD8+ CD103+ lymphocytes were found in HP patients. Among patients with sarcoidosis, 12 (29.3 %) presented a BALF CD4+/CD8+ <3.5, all of them with histological confirmation. Compared to these patients, also statistically significant higher CD4+ CD103+ counts in HP patients were observed (p = 0.007). Among HP patients, although bird fanciers (n = 14) presented higher percentages of both CD4+ CD103+ and CD8+ CD103+ T-lymphocytes than those with work-related HP (n = 5), the differences did not reach statistical significance.

Conclusions: Patients with HP present significantly higher counts of CD103+ T-lymphocytes in BALF, both in the CD4+ and CD8+ subsets, when compared to sarcoidosis, even with sarcoidosis subgroup presenting a BALF CD4+/CD8+ <3.5. The expression of CD103 may help in the interpretation of BALF data in these diffuse granulomatous lung disorders.