Elevated interleukin-2 receptor level in patients with active pulmonary tuberculosis and the changes following anti-tuberculosis chemotherapy

Soluble interleukin-2 receptor (sIL-2R) is a marker of T-lymphocyte activation. We have undertaken a study to examine the serum sIL-2R levels in patients with pulmonary tuberculosis (TB) and the changes following anti-TB chemotherapy. Forty four patients with pulmonary TB or tuberculous pleural effusion were recruited. Serum was collected from the patients before and at 1, 2, 4 and 6 months after initiation of anti-TB chemotherapy. Serum sIL-2R level was measured by an enzyme immunoassay. The mean sIL-2R level before treatment was 1,452 +/- 103 (SEM) U.ml-1, which was significantly higher than that of healthy control subjects (374 +/- 30 U.ml-1). There was no significant change in the sIL-2R level at 1 month, but there was a gradual reduction from the second month onwards. At the sixth month the mean sIL-2R level was 1080 +/- 81 U.ml-1, which was significantly lower than that before treatment. However, despite clinical improvement, the sIL-2R levels at the sixth month were still significantly higher than those of control subjects. We conclude that sIL-2R levels were elevated in patients with pulmonary TB and there was a gradual reduction following anti-TB chemotherapy. However, the sIL-2R levels were still higher than control subjects at completion of treatment, suggesting a delayed resolution of the inflammation in patients with pulmonary TB.