The data demonstrate that levels of the alpha subunit of the soluble IL-2 receptor, but not IFN-gamma, are elevated in the serum (median = 1428 U/ml; interquartile range = 823-2137 U/ml) and bronchoalveolar lavage fluid (median = 1.56 U/ml, interquartile range = 1.04-4.22 U/ml) of patients with CBD and correlate with the degree of pulmonary lymphocytosis and clinical measures of disease severity.