A IMUNOLOGIA E A IMUNOPATOLOGIA DAS INFECÇÕES CAUSADAS POR

Chlamydae are obligate intracellular bacterial pathogens of eukariotic cells responsible for a wide variety of important human and animal infections. In humans, Chlamydia trachomatis infections are generally localised on superficial epithelial or mucosal surfaces, are frequently asymptomatic and may persist for long periods of time if untreated, inducing little protective immunity. Nevertheless, neutralizing antibodies of limited efficacy are produced against the main chlamydial outer envelope protein, while gamma interferon (IFNa) is chlamydiastatic and paradoxically may play a role both in chlamydial persistence and in protective immunity. Delayed hypersensitivity responses to chalmydiae caused by repeated or persistent infection are thought to be important in the developement of the severe scarring sequelae characteristic of cicatricial trachoma and of chronic salpingitis. Chlamydial heat shock proteins bearing close homology with their human equivalents may be major targets for immunopathological responses and their expression is upregulated in IFN-a induced persistent infection. This paper reviews the immunology and immunopathology of Chlamydia trachomatis infections in the context of the clinical evolution of the infection. Key Words: Chlamydia trachomatis, imune response, immunopathology, clinical evolution of the infection.