In 2003 a randomized controlled trial on re-treated Mycobacterium tuberculosis-positive pulmonary tuberculosis conducted by Chu NH, et al. reported that sputum smear-negative conversion rates and the X-ray resolution rates of cases(n = 103) with IL-2 plus chemotherapy during the first two month preceded over the control cases (n = 106)26. Here, IL2 is linked to pulmonary tuberculosis.