Evaluation of CD30 as a marker for Th2 lymphocytes in bronchoalveolar lavage in interstitial lung diseases

Several studies have been carried out to clarify the relationship between CD30 expression and Th2 lymphocytes, although the results have been controversial. To investigate whether CD30 is a useful marker for Th2 lymphocytes in bronchoalveolar lavage (BAL) in interstitial lung diseases (ILD), we studied six control subjects and 31 patients with ILD (12 with idiopathic pulmonary fibrosis, seven with hypersensitivity pneumonitis, three with chronic eosinophilic pneumonia and nine with sarcoidosis). The levels of interleukin-5 (IL-5) (secreted by Th2 cells), interferon- γ (IFN γ) (secreted by Th1 cells) and the expression of CD30 on lymphocytes were determined in BAL fluid. There were no differences in the percentage of CD30+ lymphocytes between controls and patients with ILD (0·8±0·4%vs. 2±0·4%). In order to determine the relationship between Th2 cells and CD30 expression, we divided the patients into two groups according to BAL IL-5 levels. Group 1 consisted of eight patients (three chronic eosinophilic pneumonia, three hypersensitivity pneumonitis, two idiopathic pulmonary fibrosis) with high IL-5 levels (298±138 pg ml−1). Group II consisted of the remaining 23 ILD patients with normal IL-5 levels (0·9±0·6 pg ml−1). The percentage of eosinophils in BAL fluid was significantly higher in group I compared with group II (34±16%vs. 3±1%, P