Comparison of the Alveolitis of Sarcoidosis and Idiopathic Pulmonary Fibrosis

Abstract

Sarcoidosis and idiopathic pulmonary fibrosis (IPF) are associated with a parenchymal accumulation of inflammatory and immune effector cells (EC). Sarcoid, in contrast to IPF, is associated with parenchymal granulomata, suggesting that the EC present in the lung in sarcoid may differ from those in IPF. To evaluate this hypothesis, EC were isolated from the lung by bronchoalveolar lavage (BAL) (five sarcoid, five IPF, six normal subjects) and compared to EC in blood. To demonstrate that the EC present in BAL were representative of those present in the lung parenchyma, EC were also isolated from open lung biopsies (three sarcoid, three IPF). In IPF, the BAL was characterized by an increase in the percentage of neutrophils compared to normals (23 ± 10 vs 1 ± 1). In sarcoid, BAL was characterized by increased percentage of lymphocytes compared to normal subjects (57 ± 7 vs 7 ± 1, P < 0.001). In controls and IPF, the percentage of T-lymphocytes were similar in BAL and blood (P > 0.2 all comparisons). In marked contrast, sarcoid patients had a higher percentage T-lymphocytes in BAL compared to blood (80 ± 4 vs 57 ± 2, P < 0.001). Strikingly, the numbers of T-lymphocytes recovered by standard (100 ml) lavage of sarcoid patients were increased compared to controls (20.6 ± 4.8 × 106 vs 0.7 ± 0.2 × 106, P < 0.01), whereas the numbers of T-lymphocytes in blood of sarcoid were decreased compared to blood of normals (754 ± 184/mm3 vs 1874 ± 205/mm3, P < 0.01). In addition, the numbers of “activated” T-lymphocytes (T-lymphocytes forming rosettes with sheep red blood cells at 37°C and/or bearing a receptor for IgG) were also increased in BAL of sarcoid patients compared to normals and IPF (P<0.01). The validity of the BAL observations in sarcoid and IPF was confirmed by analysis of EC subpopulations isolated directly from the lung parenchyma (P > 0.2 all comparisons).