Serum levels of soluble interleukin-2 receptor (SIL-2R) and C-reactive protein (CRP) were measured in 12 patients with interstitial pneumonia (IP) and 10 patients with bacterial pneumonia (BP) of hematological malignancies. Mean SIL-2R levels (U/ml) were 394±140 in normal controls, 755±320 in BP, and 2328±943 in IP. A significantly higher level was found in IP than BP (p<0.05). Moreover, the SIL-2R/CRP ratio which was over 260 in all cases of IP completely distingwished IP from BP. Levels of SIL-2R rose before the onset of IP and were closely associated with clinical course in most cases. From these results, measurement of serum SIL-2R may be useful for the diagnosis and monitoring of the clinical course of IP complicated with hematological diseases.
