**3. Epidemiological evidence of antibody mediated protection**

There is accumulating evidence, in the last few decades, regarding the effect of antibodies in the context of development of pulmonary or disseminated TB. Children with low serum IgG against sonicated mycobacterial antigens and LAM, or those who could not mount antibody responses to these antigens were predisposed to dissemination of *M. tuberculosis* [16].

*M. leprae* reactive salivary IgA antibodies were suggested to be important in a mucosal protective immunity [17]. In study carried out among the Mexican Totonaca Indian population, the presence of high antibody titers to Ag87 complex antigens were observed in patients with non-cavitary TB and in patients who were cured with anti-TB chemotherapy. In contrast, patients without such antibodies had a poor outcome of the disease [18].
