Clinical significance of serum soluble IL‐2R levels in patients with adult T cell leukaemia (ATL) and HTLV‐1 carriers

The levels of soluble IL‐2Rα (sIL‐2Rα) in serum were measured in HTLV‐1 carriers and ATL patients in order to evaluate their possible correlation with clinical status. Mean sIL‐2R levels in ATL patients were found to be 9704 U/ml for the acute/lymphoma type, 1961 U/ml for the chronic type and 788 U/ml for the smouldering type. The level for asymptomatic HTLV‐1 carriers was 475 U/ml, and 165 U/ml for healthy young adult HTLV‐1 − controls. The serial measurement of sIL‐2R in ATL patients, healthy HTLV‐1 carriers, and HTLV‐1 carriers with diseases other than ATL showed a good correlation between serum levels of sIL‐2R and the pathophysiological status of disease. Furthermore, an increase in the sIL‐2Rα level in serum indicated the exacerbation of HTLV‐1 infection and autoimmune diseases. The measurement of sIL‐2Rα levels is therefore a very useful parameter for determining disease status.