SERUM-SOLUBLE INTERLEUKIN-2 RECEPTOR - A USEFUL INDICATOR OF THE CLINICAL COURSE IN PULMONARY TUBERCULOSIS

Setting: In tuberculosis both host protection and most pathogenic mech anisms depend on T lymphocytes. After activation by mycobacterial anti gens, T cells both secrete interleukin-2 (IL-2) and express a high aff inity receptor for this molecule (IL-2R) on their own surface. A solub le fraction of IL-2 receptor (sIL-2R), released from cell membrane, is detectable in serum and its concentration is known to be elevated in tuberculosis. Objective: To ascertain the role of sIL-2R as an indicat or of clinical evolution and response to antituberculosis treatment. D esign: A prospective study, in which we have measured serum sIL-2R in 52 patients (42 with active and 10 with inactive pulmonary tuberculosi s) and in 36 healthy controls. In 20 patients, serum sIL-2R levels wer e measured serially throughout the treatment. Levels of sIL-2R were co rrelated to clinical and radiological parameters. Results: Serum sIL-2 R was significantly increased in patients with tuberculosis as compare d to healthy subjects. Both the radiological findings and the clinical state of patients showed a good correlation with sIL-2R. All patients with normal values of sIL-2R 6 months after starting therapy had a fa vourable clinical evolution. Conclusion: Serum sIL-2R is a useful mark er of the clinical state and evolution of patients with pulmonary tube rculosis. The detection of permanently high values beyond 3-6 months o f treatment suggests that additional drugs or prolonged administration would be advisable in order to ensure full recovery.