Abstract

TGF-beta1 expression was studied in 25 patients with tuberculosis (lung, 9 cases and lymph node, 16 cases) using a polyclonal antibody in formalin-fixed paraffin embedded tissue. Nineteen cases (76.0%) out of 25 cases showed TGF-beta1 expression. TGF-beta1 was present in cytoplasm of epithelioid cells and Langhans' giant cells. Pulmonary tuberculosis and tuberculous lymphadenitis showed different patterns of staining. Five of 9 cases of pulmonary tuberculosis were positive for TGF-beta1: four of acid-fast bacilli positive cases (4/5, 80.0%) and one of acid-fast bacilli negative cases (1/4, 25.0%). However, high expression of TGF-beta1 was detected in tuberculous lymphadenitis of both acid-fast bacilli positive group (3/4, 75.0%) and acid-fast bacilli negative group (11/12, 91.7%). TGF-beta1 was also expressed in all of 6 cases of BCG-induced tuberculous lymphadenitis: 2 acid-fast bacilli positive and 4 acid-fast bacilli negative cases. TGF-beta1 expression was shown in 19 cases (86.4%) of 22 in active tuberculosis, while no TGF-beta1 expression was detected in any cases of inactive, healed tuberculosis (p<0.008). This study supports that the TGF-beta1 expression of epithelioid cells may alter their function resulting in the impaired antimycobacterial activity. Thus the increased production of TGF-beta1 may be one of the important mechanisms by which Mycobacterium tuberculosis avoids destruction by host macrophages.

• Keywords: Transforming growth factor-beta1 (TGF-beta1);Tuberculosis;