Cellular Analysis of Broncho-alveolar Lavage Fluid of Farmer's Lung Patients and Asymptomatic Dairy Farmers

Abstract

Farmer's lung disease (FLD) is one type of hypersensitivity pneumonitis caused by inhalation of thermophilic actinomycetes and is characterized by an increased number of lymphocytes in bronchoalveolar lavage (BAL) fluid. On the other hand, some asymptomatic dairy farmers have serum precipitin. The cells obtained by BAL from 14 patients with FLD, 9 sero-positive asymptomatic dairy farmers, 14 patients with sarcoidosis and 10 control non-smokers were analysed and compared with each other. The asymptomatic farmers were sero-positive to Micropolyspora faeni and Thermoactinomyces vulgaris, although they had no signs of any respiratory diseases and their chest roentogenogram and pulmonary function were normal. BAL was performed in the middle lobe bronchus. The cellular population was studied by May-Giemsa staining. T-lymphocyte subsets were identified by FITC-labeled monoclonal antibodies (OKT3, OKT4 and OKT8) and counted by flow cytometry. I concluded from the cell analysis of BAL fluid that 1) Lymphocyte reaction in FLD is different from that in other type of hypersensitivity pneumonitis such as pigeon breeder's lung and summer type hypersensitivity pneumonitis which reveal a predominant reaction of OKT8^+lymphocyte ; 2) An increased percentage of lymphocytes in asymptomatic farmers suggests the presence of subclinical alveolitis ; and 3) It is very difficult to make a differential diagnosis between FLD and sarcoidosis because of an occasional predominant reaction of OKT4^+ lymphocyte in FLD.