Mycobacterial heparin-binding haemagglutinin adhesion-induced interferon & antibody for detection of tuberculosis

BACKGROUND & OBJECTIVES: Mycobacterial heparin-binding haemagglutinin adhesin (HBHA) plays an important role in humoral and cellular immune response and is a potential diagnostic tool for tuberculosis (TB) serodiagnosis. This study was carried out to assess the usefulness of HBHA in TB clinics for differential diagnosis of pulmonary and extra-pulmonary TB (PTB, EPTB). METHODS: In this study, 165 outpatients and 133 healthy volunteers were included to investigate the role of HBHA in TB diagnosis including the serodiagnostic tests and the interferon-γ release assays (IGRAs). The healthy volunteers were all without BCG vaccination including 73 subjects with purified protein derivative (PPD) (-) and 60 ones with PPD (+) (that is P-B- and P+B-). Of all the 165 outpatients 77 were PTB and 88 were EPTB. HBHA protein was used for serodiagnostic tests and IGRAs in peripheral blood mononuclear cells. RESULTS: HBHA-specific antibody levels in the serum of healthy subjects were significantly different from the patients with PTB or EPTB (P<0.05). HBHA specific antibody levels in PTB patients could differentiate from EPTB with limited sensitivity (77.08%; 95%CI, 62.69 to 87.97%) and specificity (87.50%; 95%CI, 74.75 to 95.27%). IFN-γ levels in the healthy (P+B- and P-B-) groups were significantly different (P<0.01) with a detection sensitivity of 84.8% (95%CI, 68.54 to 93.02%) and specificity of 80.7% (95%CI, 65.22 to 92.62%). The PTB and EPTB subjects showed no difference in IFN-γ production. INTERPRETATION & CONCLUSIONS: HBHA serodiagnostic test with IGRAs had the limited potential for use as auxiliary tools for the differential diagnosis of PTB and EPTB, since both methods showed low sensitivity and specificity.