Acquired immune responses in the lung : their relevance to bronchiectasis

Imperial Users onl

Tuberculosis and HIV: renewed challenge

HIV infection is responsible for an increased incidence of pulmonary tuberculosis (TB) in several areas of the world. In general, active TB happens as a consequence of a recently acquired exogenous infection of Mycobacterium tuberculosis or of endogenous reactivation of old infection. In some regions, besides the increase of the incidence, an important change in the dynamics of the transmission of M. tuberculosis took place. This change was more evident in closed places (hospitals, prisons, housings) where the prevalence of inmates infected by HIV is high. The infection by HIV also interferes with the diagnosis of TB, especially in patients in the advanced form of the HIV infection. In these cases, the clinical picture of TB is quite similar to other opportunistic infections . HIV seropositive patients tend to stay longer in hospitals, increasing the risk of transmission of TB or even of multidrug resistant TB (TB-MDR) to other patients, health care workers and students in teaching institutions (Alland et al. loc. cit., Frieden et al. loc. cit.). The clinical evolution of co-infected patients is diverse from immunocompetent individuals, with higher rate of adverse drugs reaction and mortality. The emphasis given in the last decades to outpatient treatment of TB should be now revised in areas with high rate of TB and AIDS, especially in great urban centers. Hospital treatment of tuberculosis patients with co-morbidities, such as AIDS, is much more common now. Should be taken into account in the elaboration of public politics the occurrence of TB in general hospitals, above all in developing countries, such as Brazil

Phenotypes of lung mononuclear phagocytes in HIV seronegative tuberculosis patients: Evidence for new recruitment and cell activation

Mycobacterium tuberculosis preferentially resides in mononuclear phagocytes. The mechanisms by which mononuclear phagocytes keep M. tuberculosis in check or by which the microbe evades control to cause disease remain poorly understood. As an initial effort to delineate these mechanisms, we examined by immunostaining the phenotype of mononuclear phagocytes obtained from lungs of patients with active tuberculosis. From August 1994 to March 1995, consecutive patients who had an abnormal chest X-ray, no demostrable acid-fast bacilli in sputum specimens and required a diagnostic bronchoalveolar lavage (BAL) were enrolled. Of the 39 patients enrolled, 21 had microbiologically diagnosed tuberculosis. Thirteen of the 21 tuberculosis patients were either HIV seronegative (n = 12) or had no risk factor for HIV and constituted the tuberculosis group. For comparison, M. tuberculosis negative patients who had BAL samples taken during this time (n = 9) or normal healthy volunteers (n = 3) served as control group

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

Developments in Impact Assessment of New Diagnostic Algorithms for Tuberculosis Control

A modified presentation of the impact assessment framework is proposed that improves accessibility while continuing to provide a checklist of the evidence needed to support policy decisions on the implementation of new tools for the diagnosis of tuberculosis