Mycobacterium Tuberculosis Heparin-binding Hemagglutinin Of Immune Function

Heparin-binding hemagglutinin adhesin (HBHA) is a surface-exposed protein of Mycobacterium tuberculosis (MTB) which involves to adhesion. Its molecular weight is about 28kDa, and it is methylated at its Lys-rich carboxyl-terminal domain by post- translational modification, which is important to protect the protein from proteolytic degradation and certain immunologic properties. It plays an important role during the process of MTB invading epithelia of respiratory, and it is required for extra-pulmonary dissemination. Some studies have approved that HBHA specific cell-mediated immune (CMI) and humoral response are different in people of different infection status including the healthy control, latent tuberculosis infection (LTBI),pulmonary and extrapulmonary tuberculosis. It can stimulate PBMCs of LTBI to secrete high level IFN-γ, suggesting that it can offer good immune protection.This study was to investigate the immune effects of HBHA in different people and different infection status of tuberculosis,and to estimate its potential immune protection and diagnostic value. Native HBHA and PPD were used to stimulate PBMCs from different infected-cases enrolled, and the interferon-gamma in the supernatant of culture was detected. Meanwhile, HBHA specific IgG antibody in the sera was detected by ELISA method with EIA plates which was pre-coated with native HBHA. The antibody level represents the humoral immune response. The immune effect of HBHA to different people was compared by combining the cell mediated immune and humoral immune responses. The results showed that HBHA specific IFN-γlevel of latent tuberculosis is much higher than that of the control, and slightly higher than that of the patients of pulmonary and extra-pulmonary tuberculosis, the concentration of IFN-γbetween the patients of pulmonary and extra-pulmonary tuberculosis after stimulation with HBHA and PPD showed no significant difference. And by sera antibody detection, the IgG antibody to HBHA of pulmonary patients is higher than that of the healthy, including the control and the latent tuberculosis infection, and slightly higher than extra-pulmonary patients. That is to say, cell mediated immune response is dominant in LTBI, but to patient of tuberculosis the humoral immune response is.The experiment conformed that HBHA has good immunogenicity and it can stimulate the LTBI to release high level IFN-γ, suggests that the LTBI doesn't develop active tuberculosis may rely on its protection. And it can be deduced from the data that it is not humoral immune response but the cell mediated immune response that protects the LTBI to develop active tuberculosis. It is important to identify latent tuberculosis from healthy and to control tuberculosis'prevalence. But it has no significance in the identification of pulmonary tuberculosis and extrapulmonary tuberculosis though it has been conformed important in the extra-pulmonary dissemination of mycobacterium tuberculosis.