Diagnosis of pulmonary tuberculosis using MTB12 and 38-kDa antigens

Background and objective: Mycobacterium tuberculosis MTB12 protein plays an essential role in pro‐inflammatory responses during the early stages of human pulmonary tuberculosis (TB), even though the T‐cell immunoreactivity of MTB12 is weaker than that of the 30‐kDa antigen (Ag). The objective of this study was to evaluate the humoral immune responses induced by MTB12 Ag during human TB. Methods: Using an ELISA, anti‐MTB12 IgG levels in the sera of TB patients and healthy controls were compared with those induced by the 30‐kDa Ag and 38‐kDa Ag, or both. Results: In TB patients, the sensitivity and specificity of MTB12 Ag were similar to those of other antigens at 53.0% and 95.4%, respectively. However, the sensitivity increased to 73.0% when the combination of MTB12 and 38‐kDa Ag was measured. Specificity remained high when a combination of the individual antigens was used. ELISA results showed that after anti‐tuberculosis treatment, the mean IgG levels against MTB12 alone or MTB12 plus 38‐kDa Ag were significantly increased in the TB patients, while those against MTB12 plus 30‐kDa Ag were not (P