RESEARCH NOTE - Immune response during HIV and tuberculosis co-infection

The human immunodeficiency virus type 1 (HIV-1) and Mycobacterium tuberculosis, the etiologic agent of tuberculosis (TB), co-infect around 6 million people worldwide. In Rio de Janeiro, Brazil, 24% of notified AIDS cases had TB and 5 to 20% of notified TB cases are HIV-1 seropositive. Several authors have already described the deleterious association between these two microorganisms. Here, we will overview the immune response to M. tuberculosis and the effect of association with HIV-1 infection. The natural history of M. tuberculosis infection indicates that the emergence of delayed-type hypersensitivity (DTH) and presumably specific acquired resistance is associated with control of the initial infection in 95% of normal hosts; the other 5% develop progressive primary TB. In addition, 5-10% of the infected persons eventually will reactivate latent pulmonary or extrapulmonary foci several years after infection. HIV-infected individuals and AIDS patients have a remarkable susceptibility to TB, increasing 113-fold and 170-fold the risk of TB reactivation, respectively. In addition, it has been shown that TB accelerates the HIV infection and disease progression.