Interstitial lung disease in systemic sclerosis: comparison of BALF lymphocyte phenotype and DLCO impairment

Patients with scleroderma (systemic sclerosis-SSc) frequently develop an interstitial lung disease. The role of lymphocytes in fibrosing alveolitis preceding lung fibrosis has been established. The purpose of this work was to evaluate cell profiles and lymphocyte phenotypes in the bronchoalveolar lavage (BAL) fluid and to correlate them with depression in lung function tests detected by depletion of diffusing capacity (DLCO). BAL was carried out in 25 untreated, non-smoking patients suffering from diffuse scleroderma and in 12 healthy non-smoking volunteers. For the analysis of lymphocyte sub-sets flow cytometry and monoclonal antibodies were used. The following cell sub-types were counted: T lymphocytes, B lymphocytes, helper lymphocytes, suppressor/cytotoxic lymphocytes, natural killer cells, cytotoxic T lymphocytes and activated T lymphocytes. The total cell count was higher in the group of patients with mild and moderate impairment in DLCO. The percentage of lymphocytes was greater in patients with DLCO lower than 65% of the predicted value since neutrophilia was found in patients with severe DLCO depletion, i.e. significant when compared with healthy subjects. The proportions of suppressor/cytotoxic lymphocytes and of activated T lymphocytes were higher in patients than in controls. The statistical analysis revealed significant differences between patients with moderate and mild changes in DLCO and the healthy volunteers. A decreased helper/suppressor ratio was noticed in these patients. We concluded that the BALF lymphocyte phenotype analysis may reflect the features of alveolitis in patients with SSc.