Correlation of CD4 : CD8 ratio and tumour necrosis factor (TNF)alpha levels in induced sputum with bronchoalveolar lavage fluid in pulmonary sarcoidosis

Background-An increased CD4:CD8 lymphocyte ratio and raised cytokine levels in bronchoalveolar lavage (BAL) fluid are characteristic of pulmonary sarc oidosis. Sputum induction has been used as a non-invasive tool for investig ating the airways and may be useful in investigating inflammation in patien ts with sarcoidosis in whom endobronchial, peribronchial, and parenchymal i nflammation is present. This study aimed to correlate the total and differe ntial cell counts, CD4:CD8 ratio, and tumour necrosis factor (TNF)alpha lev els between induced sputum and BAL fluid in patients with pulmonary sarcoid osis. Methods-Fourteen patients with newly diagnosed biopsy proven sarcoidosis an d six healthy controls were investigated. Sputum induction and BAL was carr ied out at the initial visit and repeated following six months of treatment with oral prednisone. Results-There was no correlation of differential cell counts between induce d sputum and BAL fluid. The CD4:CD8 ratio in induced sputum correlated stro ngly with that in BAL fluid (5.5 (0.4:1) versus 4.4 (0.2:1); r = 0.8, p<0.0 01) and the fall in the ratio following six months of treatment in sputum p aralleled that in BAL fluid (3.4 (0.2:1) versus 2.4 (0.2:1)). The TNF alpha levels in sputum also correlated with levels in the BAL fluid (11.9 (1.5) pg/ mi versus 17.6 (2.7) pg/ml; r = 0.8, p<0.001). The fall in sputum TNF a lpha levels following six months of treatment paralleled the fall in BAL fl uid levels (6.7 (0.9) pg/ml versus 11.6 (1.3) pg/ml). Conclusions-The CD4:CD8 ratio and TNF alpha levels in induced sputum correl ated with those in BAL fluid and paralleled changes with treatment. Induced sputum may therefore be a non-invasive surrogate for certain parameters in BAL fluid in patients with sarcoidosis.