Effects of BAL Fluid on Neutrophil Function in Rheumatoid Arthritis

Abstract

Rheumatoid arthritis (RA), a systemic inflammatory disease of unknown etiology, is associated with a variety of pulmonary abnormalities including interstitial lung disease. Although the pathogenesis of interstitial lung disease in RA is poorly understood, we have previously defined bronchoalveolar lavage (BAL) abnormalities of the lower respiratory tract in RA patients with interstitial lung disease and in a subset of patients without clinical lung involvement. 1 Garcia JG Lewis EP Garcia PL Keogh BA Bronchoalveolar lavage assessment of clinical and subclinical lung involvement in rheumatoid arthritis [Abstract]. Am Rev Respir Dis. 1985; 131: 78 Google Scholar These findings include abnormalities of BAL cell differentials, T-lymphocyte subsets, immunoglobulins, and fibronectin and are summarized in Table 1. Patients with clinical interstitial lung disease demonstrated an elevation in BAL neutrophils, a potent inflammatory cell that can contribute to lung injury via protease and oxidative mechanisms. Neutrophils appear to be important effector cells in the pathogenesis of idiopathic pulmonary fibrosis (IPF), 2 Crystal RG Bitterman PB Rennard SI Hance AJ Keogh BA Interstitial lung diseases of unknown cause: disorders characterized by chronic inflammation of the lower respiratory tract. N Engl J Med. 1984; 310 (310(4): 235-44): 154-166 Crossref Scopus (432) Google Scholar an interstitial disorder histologically resembling rheumatoid interstitial lung disease. To evaluate potential mechanisms of neutrophil recruitment and activation in rheumatoid interstitial lung disease, we assessed BAL fluid from RA patients with and without clinical interstitial involvement for the capacity to recruit and activate these effector cells. Table 1BAL Abnormalities in Rheumatoid Arthritis Patient Groups Group 1 2 3 No. of Patients 9 5 10 Clinical interstitial lung disease 9/9 0/5 0/10 BAL cell differential % Neutrophils ↑ * Group 1 vs 2 and 3, p <0.05. N † N = Normal. N % Lymphocytes N ↑ ‡ Group 2 vs 1 and 3, p <0.05. N % Eosinophils N N N BAL T-lymphocyte helper/suppressor ratio ↓ * Group 1 vs 2 and 3, p <0.05. ↓ N BAL immunoglobulin levels IgG and IgA N N N IgM ↑ § Group 1 and 2 vs 3, p <0.05. ↑ § Group 1 and 2 vs 3, p <0.05. N BAL fibronectin levels (>4 μg/mg albumin) 6/9 § Group 1 and 2 vs 3, p <0.05. 2/5 § Group 1 and 2 vs 3, p <0.05. 0/10 * Group 1 vs 2 and 3, p <0.05. † N = Normal. ‡ Group 2 vs 1 and 3, p <0.05. § Group 1 and 2 vs 3, p <0.05. Open table in a new tab