SOLUBLE INTERLEUKIN-2 RECEPTOR IN BLOOD FROM PATIENTS WITH SARCOIDOSIS AND IDIOPATHIC PULMONARY FIBROSIS

Soluble interleukin-2 receptor (sIL-2R) concentration is considered to reflect disease activity in patients with sarcoidosis. However, it re mains to be evaluated whether or not the sIL-2R concentration reflects the total burden of granulomatous lesions, or if it can be a useful m arker for other interstitial lung diseases such as IPF, the lesions of which are restricted to the lungs. In this study, we demonstrated tha t sIL-2R concentrations in 16 patients with active sarcoidosis increas ed (2031 +/- 1222 U/ml), compared to those in 29 patients with inactiv e disease (796 +/- 313), 24 with IPF (859 +/- 694) and 33 healthy cont rols (467 +/- 174). sIL-2R concentrations in patients with IPF also in creased, more than those in healthy subjects. sIL-2R concentrations in 10 patients with extrathoracic lesions (ETL) were not different from those in 6 patients without ETL. Correlation between serum sIL-2R conc entrations and serum ACE activity, BAL macrophage %, and BAL lymphocyt e % was shown in patients with sarcoidosis. In patients with IPF, a co rrelation between sIL-2R concentrations and BAL macrophage % was found but there was no correlation between sIL-2R concentrations and BAL ly mphocyte %. In conclusion, serum sIL-2R concentrations seem to reflect total inflammatory lesions. In addition, they reflect total inflammat ory lesions of the lungs in sarcoidosis and IPF. For clinical purposes , its measurement may be more useful than that of BAL fluid concentrat ions in patients with sarcoidosis and IPF.