CC chemokines play an important role in the pathogenetic mechanisms of interstitial lung disease, while a downregulation of CC chemokine receptor (CCR)5 in the fibrotic stages of sarcoidosis has been observed. To evaluate the involvement of CC chemokines and the expression of CCR5 in idiopathic pulmonary fibrosis (IPF) and, more specifically, in usual interstitial pneumonia, 35 subjects were studied. CC chemokine ligand (CCL)2, CCL3 and CCL4 levels were measured in the bronchoalveolar lavage fluid (BALF) of 18 nonsmoker control subjects and 17 patients affected by IPF. CCR5 expression was evaluated in alveolar macrophages and lymphocytes. The BALF levels of all chemokines were significantly increased in IPF: median (range) CCL3 1.6 (1.0-11.1) versus 1.2 (0.0-3.8) pg x mL(-1); CCL4 6.2 (1.3-96.0) versus 3.4 (0.3-6.8) pg x mL(-1); and CCL2 60.1 (16.7-251.3) versus 4.6 (0.5-119.4) pg x mL(-1). CCL2 levels correlated negatively with the carbon monoxide diffusing capacity of the lung (D(L,CO)) and arterial oxygen tension. CCR5 expression was significantly reduced in lymphocytes from IPF compared with controls. The CC chemokines investigated are involved in the inflammatory mechanisms of idiopathic pulmonary fibrosis, and the results are in agreement with the hypothesis of a downregulation of the T-helper 1 immunological response in this disease.