Immune reconstitution inflammatory syndrome

Overview
Immune reconstitution inflammatory syndrome (IRIS) or immune reconstitution syndrome (IRS) is a condition seen in some cases of AIDS or immunosuppression, in which the immune system begins to recover, but then responds to a previously acquired opportunistic infection with an overwhelming inflammatory response that paradoxically makes the symptoms of infection worse.

The suppression of CD4 T cells by HIV (or by immunosuppressive drugs) causes a decrease in the body's normal response to certain infections. Not only does this make it more difficult to fight the infection; it may mean that a level of infection that would normally produce symptoms is instead undetected (subclinical infection). If the CD4 count rapidly increases (due to effective treatment of HIV, or removal of other causes of immunosuppression), a sudden increase in the inflammatory response produces nonspecific symptoms such as fever, and in some cases a worsening of damage to the infected tissue.

Though these symptoms can be dangerous, they also indicate that the body may now have a better chance to defeat the infection. The most common treatment is to administer antibiotic or antiviral drugs against the infectious organism, and in some cases corticosteroids to suppress inflammation until the infection has been eliminated.

Infections most commonly associated with IRIS include cytomegalovirus, herpes zoster, Mycobacterium avium complex (MAC), Pneumocystis pneumonia, and tuberculosis. AIDS patients are more at risk for IRIS if they are starting HAART for the first time, or if they have recently been treated for an opportunistic infection. It is generally advised that when patients have low initial CD4 T cell count and opportunistic infection at the time of their HIV diagnosis, they receive treatment to control the opportunistic infections before HAART is initiated.

IRIS in cryptococcal meningitis
IRIS has been described in immunocompetent hosts who have meningitis caused by Cryptococcus gattii and Cryptococcus neoformans var. grubii, environmental fungi which often affect immunocompetent hosts. Several weeks or even months into appropriate treatment, there is a sudden onset deterioration with worsening meningitis symptoms and progression or development of new neurological symptoms.

Reference

 * Shelburne, S.A., Visnegarwala, F., Darcourt, J., Graviss, E.A., Giordano, T.P., White Jr., A.C. and Hamill R.J. (2005) Incidence and risk factors for immune reconstitution inflammatory syndrome during highly active antiretroviral therapy. AIDS 19, 399-406. PMID 15750393

External link

 * The Body