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 C D30 expression and Th2 lymphocytes, although the results have been controve rsial. To investigate whether CD30 is a useful marker for Th2 lymphocytes i n bronchoalveolar lavage (BAL) in interstitial lung diseases (ILD), we stud ied six control subjects and 31 patients with ILD (12 with idiopathic pulmo nary fibrosis, seven with hypersensitivity pneumonitis. three with chronic eosinophilic pneumonia and nine with sarcoidosis). The levels of interleuki n-5 (IL-5) (secreted by Th2 cells), interferon-gamma (IFN gamma) (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 + lymphocyte s between controls and patients with ILD (0.8+/-0.4% vs. 2+/-0.4%). In orde r to determine the relationship between Th2 cells and CD30 expression, we d ivided the patients into two groups according to BAL IL-5 levels. Group 1 c onsisted of eight patients (three chronic eosinophilic pneumonia, three hyp ersensitivity 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< 0.05). A correlation between CD30 lymphocytes and IL-5 in group 1 was not shown. There were no differences in the number of CD30+ lymphocytes between both groups (3+/-1% vs. 1.8+/-0.5% ). In group I we found a significant correlation between IL-5 levels and th e percentage of eosinophils (r = 0.95. P<0.0001). Our results suggest that CD30 does not appear to be a useful marker for Th2 lymphocytes in BAL from patients with ILD.