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.