Diagnostic value of tuberculosis-Specific antigens Ag85B, ESAT-6 and CFP10 in pulmonary tuberculosis

• IHC detect Ag85B, ESAT-6, and CFP10 is meaningful in PTB. • Positivity of all antigens is crucial in PTB3.Negativity of all antigens exclude PTB. • Simultaneous positivity of all three antigens is crucial for confirming tuberculosis. • Collective negativity of all three antigens is significant in ruling out pulmonary tuberculosis. To assess the diagnostic value of tuberculosis-secreted Ag85B, ESAT-6 and CFP10 in pulmonary tuberculosis. Immunohistochemical (IHC) and acid-fast staining were performed, the detection efficiency of the two methods were analysed with chi-square test. Acid-fast staining demonstrated a sensitivity of (18/69, 26.09%) and a specificity of 100%. IHC staining for Ag85B, ESAT-6 and CFP10 was positive in all 18 cases with positive acid-fast staining and additionally positive in 25,36 and 30 cases, respectively, that were acid-fast-negative. The sensitivities of IHC staining for Ag85B, ESAT-6 and CFP10 were 62.32%, 78.26% and69.57%, respectively, while their specificities were 86.57%, 85.07% and 91.04%, respectively. Joint antigen analysis revealed that simultaneous positivity for two or three of Ag85B, ESAT-6 and CFP10 increased specificity (95.52% to 100%) but decreased sensitivity (49.28% to 62.31%). The presence of any one of the three antigens elevated sensitivity (81.16% to 88.41%) but lowered specificity (68.66% to 77.61%). Specificity reached 100% for concurrent positivity of all three antigens, while a sensitivity of 88.41% was observed for positivity of any one antigen. Ag85B, ESAT-6, and CFP10 exhibits greater sensitivity in pulmonary tuberculosis and combined antigen testing enhances the diagnostic accuracy.