| At present, over a third of the world population is infected with tubercle bacilli , which is responsible for more than 2 million deaths annually, according to the world Heath Organigation. Epidemiologists estimate that the infected population is approximately five hundred and fifty million in china and 1.32 million new cases of tuberculosis occur a year. The majority of these new cases may results from the reactivation of a latent infection and not from a recently acquired Mycobacterium tuberculosis infection. Therefore, the detection and treatment of individuals with latent tuberculosis infection and a high risk of progression to active tuberculosis are the major components of tuberculosis control strategies.The influences of different tuberculosis states and BCG inoculation on the antibody response were involved in some medical fields, such as new prophylactic interventions and immunology therapeutics,development of tuberculosis vaccine,serodiagnosis for tuberculosis,tuberculosis epidemiological monitorin and clinical therapy of tuberculosis,etc, It is valuable for academic research and has an extensive application for epidemic investigation and clinic treatment in tuberculosis.It contains around 4000 proteins in a cell of tubercle bacillus, and most of them are immunogenic. Besides, there are polysaccharides and Lip polysaccharides in the cell. Therefore, variety of the antibodies against these antigens exists. In the present study, three antigens of M?tuberculosis (PPD, 38 kDa protein and LAM) which had been used for serodiagnosis of tuberculosis extensively ,were adopted in this study to investigate the corresponding antibody response levels and characteristics in the patients with active disease (clinical tuberculosis), latent infection (sub clinical tuberculosis) and the recruits with BCG inoculation.The diagnostic tests for catent tuberculosis infection include the tuberculin skin test (TST) and Interferon– gamma Release Assays (IGRAS). The most commonly used method for detection of latent tuberculosis infection, TST, has low specificity. IGRAS were uneffected by prior Mycobacterium bovis BCG vaccination. However, neither IGRAS nor the TST can separate active tuberculosis from latent tuberculosis infection, and there is concern that response in IGRAS may decline with time after infection and the prognostic use of IGRAS has not found as yet.Firstly, the antibody response levels to three antigens among the recruits, who had been inoculated with BCG, were monitored continuously . It was found that the anti-LAM and anti-38 kDa antibodies remained negative throughout the observation period, but the mean titer of anti-PPD antibody elevated significantly at week 4 compared with the pre-vaccination, peeking at week 13, showing a higher level half year post-vaccination. These results showed that serological diagnosis using anti-PPD antibody was influenced severely by prior BCG vaccination.According to the investigation of antibody titer to the 38 kDa protein in the recruits with TST strong positive, followed by a visit to those with anti-38 kDa antibody positive during one year, the indices of TST strong positive and anti-38 kDa antibody positive could be taken as the indicators of latent infection of tubercle bacillus. It was suggested that, the recruits with anti-38 kDa antibody positive and TST strong positive should be given a prophylactic therapy, which might be the most effective and economic to reduce the incidence and to decrease the epidemic outbreak of tuberculosis in army. The antibody to LAM was negative in latent infection and an assay for antibody to PPD had no discrimination between latent infection and active disease.The investigation on immune response in patients received chemotherapy,showed that the antibody titer to PPD had a rise continually within 2 months of treatment,and peaked at mean 1.8 months of treatment and had 2~3 times titer than those before anti-TB chemotherapy. Then antibody titer decreased gradually. For the patients with small focal lesion, smear negative and low titer, there was no change in anti-PPD antibody level after therapy.In conclusions, the characteristics of antibody response to three antigens in patients with clinical infection, with latent infection and recruits received BCG vaccination were investigat in this study. It is clear that some serodiagnostic tests were suitable to find tuberculosis cases in recruits and new students, and the effective method should be adopted to discriminate the latent infection in recruits,and that the new prophylactic measures had been suggested for tuberculosis control in army. A preliminary study on antibody response characters and its application in tuberculosis had been performed.
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