Tuberculosis and tuberculosis-associated immune reconstitution inflammatory syndrome in HIV: immunological review of manifestation and immunopathogenesis

Abstract

Tuberculosis (TB) is the most common opportunistic infection that makes human immunodeficiency virus (HIV) infection more complicated. TB-immune reconstitution inflammatory syndrome (TB-IRIS) mainly refers to an excessive immune response among HIV-infected patients. In HIV-infected patients, IRIS occurs after initiation of antiretroviral therapy (ART), irrespective of increased CD4 count and effective suppression of HIV viremia; IRIS may occur at any stage in the progression of immunodeficiency and manifests with weakened immune system. IRIS is associated with various inflammatory processes as the outcome of immunological reaction against a variety of opportunistic infections (OIs). Currently, there is no reliable biological marker available for diagnosis of TB-IRIS. In accordance with current clinical case definition, deterioration of clinical and radiological symptoms of pre-existing TB infection in HIV patients is called “paradoxical TB-IRIS”. The appearance of a previously undiagnosed or new TB infection during ART treatment is called “unmasking TB-IRIS”. IRIS is a challenging complication for researchers and medical practitioners, as the incidence of IRIS is between 3-40% in patients initiated on ART. The variation in incidence probably reflects the differences in case definitions, patients’ population studied, and individual resource-limited settings. The immune pathogenesis of IRIS is poorly understood, and epidemiology partially defined. The complication for clinicians remains challenging in terms of diagnosis and treatment as well as patients’ suffering, even though, the mortality is typically low.

Keywords

• hiv
• t cells
• unmasking
• paradoxical
• tb-iris