Immune reconstitution inflammatory syndrome in HIV

The purpose of this review is to describe the epidemiology, clinical features, putative immune mechanisms and management of immune reconstitution inflammatory syndrome (IRIS) using data published in the last 2 years.

Ever more conditions are reported as IRIS events. These most frequently occur with mycobacterial (tuberculosis or Mycobacterium avium complex infection) or cryptococcal disease (each in approximately 30% of cases). Definitions have been proposed for its clinical diagnosis. These suffer from a lack of prospective studies to support their predictive value. The immunopathogenesis of IRIS appears to be related to the interaction between HAART-induced changes in host immune response and the presence of (usually microbial) antigen. Increasing evidence exists that this might be an anatomically compartmentalized phenomenon, such that immune responses may be localized to specific tissue sites such as the brain. This has implications for the use of simple blood tests, such as CD4 count or change in viral load, when assessing risk of IRIS. Treatment options include immune modulation, though supportive care is typically all that is required, unless symptoms are prolonged, significant or life-threatening.

IRIS is common and will become more so as HAART is rolled out worldwide. Clear clinical definitions are required to avoid its over-diagnosis due to misclassification of other conditions.