The use of induced sputum in the assessment of pulmonary involvement in Crohn's disease

OBJECTIVE: Our aim was to evaluate lung involvement in Crohn's disease (CRD ) patients by induced sputum (IS). Extraintestinal manifestations are frequ ent in CRD, but lung involvement is rare. Induced sputum is a reliable noni nvasive method of investigating the pathogenesis, pathophysiology, and trea tment of lung disease. METHODS: Twenty-four CRD patients and nine control subjects (all nonsmokers ) without respiratory symptoms were tested. Sputum was induced by 20' inhal ation of 3.5% saline using ultrasonic nebulizer. Samples were studied by di fferential counts of 200 cells on cytopreps stained by Giemsa. T-lymphocyte subset analyses were done by FAGS using three monoclonal antibodies: CD3 = total T cells, CD4 = T helper cells, and CD8 = T suppressor-cytotoxic cell s. CD4/CD8 >2.5 was considered abnormal. RESULTS: Four patients did not produce sputum. Of the remaining 20 patients , seven had active CRD and 13 were in remission. They were divided into two groups: Group A patients had abnormal CD4/CD8 ratio of 6.7 +/- 2.5; Group B (seven patients) had normal CD4/CD8 ratio of 1.7 +/- 0.52 (p = 0.0001). T he differential counts of IS samples were similar in both groups, but lymph ocyte count was significantly higher in CRD patients than in the control gr oup (13.2 +/- 11.2 vs 4.8 +/- 3.6, p = 0.036). There were no differences in spirometry, treatment, extent, or activity of CRD. CONCLUSION: Using a simple noninvasive method, we found that among CRD pati ents without respiratory symptoms there was a high (65%) incidence of lung involvement. (Am J Gastroenterol 2000;95:730-734. (C) 2000 by Am. Coll. of Gastroenterology).