Predictive value of response to treatment of T-lymphocyte subpopulations in idiopathic pulmonary fibrosis

T-cell types are important in maintaining immune homeostasis in the lung and their imbalance may be associated with several diseases. We examined the relationship between bronchoalveolar lavage (BAL) T-cell subset profiles and the clinical course of 46 patients with idiopathic pulmonary fibrosis (IPF). A flow cytometry cell sorter (FACS) was used to analyse the T-cell subsets. Pulmonary function tests (PFT) were performed at baseline and 6-12 months later. Patients were divided into two groups according to their CD4/CD8 ratio: CD4/CD8 >1 (group 1, n=21); and CD4/CD8 <1 (group 2, n=25). A lower percentage of lymphocytes, a higher percentage of CD8/S6F1 cells (cytotoxic T-lymphocytes) and a higher percentage of neutrophils were found in the BAL in group 2 compared to group 1 (11±7.5% versus 19±13.2%; p=0.024 and 29.8±17.6% versus 13.3±6.9%; p=0.068, respectively for lymphocytes and cytotoxic T-lymphocytes; and 8±11% versus 29±27%; p=0.003 for neutrophils). Inversely, in the peripheral blood, the distribution of CD8/S6F1 cells was lower in group 1 than in group 2 (8.3±6.9% versus 33.4±16.5%; p=0.0048). The patients were followed over a period of 1 yr in order to test whether those findings could determine efficacy of therapy. The baseline transfer factor of the lung for carbon monoxide (TL,CO) capacity in group 1 and group 2 was 59±22% and 51±21%, respectively (p=0.29), but only in group 1 was the TL,CO capacity improved significantly in response to steroids treatment after 6-12 months. IPF patients with a higher percentage of lymphocytes, a lower percentage of neutrophils, CD4/CD8 >1 and a low percentage of CD8/S6F1 may have a more benign course of disease. These parameters may identify an early stage of reversible disease responsive to therapy. We conclude that these measurements may be a useful tool in monitoring response to treatment in patients with idiopathic pulmonary fibrosis.