Iris

Hey there! I'm Orris, your AI assistant. How can I help you today?

Immune reconstitution inflammatory syndrome

Reading File

Searching PubMed

immune reconstitution inflammatory syndrome IRIS

Finding Sources

Reading File

I now have rich, comprehensive content from multiple authoritative textbooks. Here is the full, synthesized answer:

Immune Reconstitution Inflammatory Syndrome (IRIS)

Definition

IRIS is a paradoxical worsening of clinical status that occurs when a previously severely immunosuppressed patient's immune system begins to recover. It manifests as an exuberant, often disorganized host inflammatory response to previously recognized or subclinical antigens. The syndrome most commonly develops after initiation of antiretroviral therapy (ART) in HIV-infected patients. - Murray & Nadel's Textbook of Respiratory Medicine, p. 2866

Types

Type	Description
Paradoxical IRIS	Patient has a known infection, responds to treatment, then paradoxically worsens after starting ART
Unmasking IRIS	Patient starts ART without a known infection; immune recovery reveals a previously subclinical (silent) infection

Fishman's Pulmonary Diseases and Disorders, p. 2371-2372

Pathogenesis

IRIS is thought to result from:

Dysregulation of rising CD4+ T cells that are highly antigen-specific, mounting a disproportionate inflammatory response
Hyperresponsiveness of the innate immune system to helper T cells
In cryptococcal IRIS specifically: pre-ART elevations in Th2 and Th17 cytokines (IL-17, IL-4), reduced pro-inflammatory cytokines (TNF-alpha, G-CSF), and high titers of serum/CSF cryptococcal antigen

There is an inverse correlation between baseline CD4 count and the probability of developing IRIS - lower CD4 counts at ART initiation mean higher IRIS risk. - Firestein & Kelley's Textbook of Rheumatology

Risk Factors

CD4 count <50-100 cells/μL at ART initiation (greatest risk below 50 cells/μL)
Initiating ART shortly after diagnosing an opportunistic infection
Rapid virologic and immunologic response to ART
High pathogen burden at time of ART initiation
IRIS can also occur in transplant recipients when immunosuppressive therapy is withdrawn rapidly

Timing

The majority of cases occur within the first 1-3 months after ART initiation, though cases can present several months later. - Murray & Nadel's, p. 2866

Common Triggers / Associated Conditions

Infections (most common):

Mycobacteria - M. tuberculosis and MAC are the most frequently encountered
Fungal - Cryptococcus (especially meningitis), PCP (Pneumocystis)
Viral - CMV
Leprosy (can flare after ART initiation)

Non-infectious:

Sarcoidosis (may be unmasked or worsen)
Autoimmune diseases appearing de novo: RA, SLE, polymyositis, autoimmune hepatitis, Guillain-Barre syndrome, adult-onset Still's disease
Malignancies - tumors may paradoxically worsen
Cerebral CD8 lymphocytosis, alopecia universalis, terminal ileitis
Firestein & Kelley's Textbook of Rheumatology; Murray & Nadel's Respiratory Medicine

Diagnostic Criteria

All of the following should be present:

Diagnosis of AIDS
Currently on ART with evidence of increase in CD4 count and decrease in HIV viral load
Exaggerated inflammatory response to infection
Inflammatory symptoms appearing during ART that cannot be explained by another cause (other opportunistic infections, drug toxicity, treatment failure)

Firestein & Kelley's Textbook of Rheumatology, p. 6620-6622

Special Considerations: Cryptococcal Meningitis-IRIS

This warrants particular caution because the CNS has limited anatomical flexibility, making IRIS here more lethal than extra-CNS IRIS.

Deferring ART by 4-5 weeks (rather than starting immediately) after diagnosing cryptococcal meningitis is associated with significantly improved survival, especially in patients with few CSF white cells
This is the one important exception to the general rule of starting ART as soon as possible after diagnosing an OI
Screening for cryptococcal antigen (CrAg) in asymptomatic patients with CD4 <100 cells/mm³ before starting ART is WHO-recommended to prevent unmasking IRIS
Goldman-Cecil Medicine; Fishman's Pulmonary Diseases, p. 2373-2375

TB-IRIS and the PredART Trial

Prophylactic prednisone reduces the risk of TB-associated IRIS in high-risk individuals (CD4 <100 cells/μL, within 30 days of TB treatment initiation)
Regimen: prednisone 40 mg/day x 14 days, then 20 mg/day x 14 days
This was established in the PredART Clinical Trial, without increased risk of other severe infections or cancers
TB-IRIS may contribute to long-term spirometric abnormalities in HIV/TB patients
Murray & Nadel's Respiratory Medicine, p. 2866

Management

Severity	Management
Mild IRIS	Continue ART; supportive care only
Moderate IRIS	NSAIDs to reduce inflammation
Severe IRIS (CNS, airway compromise)	Corticosteroids (prednisone 1.5 mg/kg/day x 2 weeks, then 0.75 mg/kg/day x 2 weeks)
Cryptococcal meningitis IRIS with raised ICP/cerebral edema	Corticosteroids under expert guidance (though steroids are otherwise unhelpful or detrimental in cryptococcal disease)

ART should generally be continued in patients who develop IRIS; stopping is rarely necessary
Carefully consider each case individually; expert consultation recommended
JAK inhibitors - a recent clinical trial suggests they may be effective in preventing inflammatory complications of ART (emerging evidence)
Murray & Nadel's Respiratory Medicine, p. 2866; Goldman-Cecil Medicine; Firestein & Kelley's Rheumatology, p. 6630

Key Points Summary

Feature	Detail
Setting	HIV/AIDS patients starting ART; also post-transplant on reduced immunosuppression
Timing	Typically 1-3 months after ART initiation
Hallmark	Paradoxical worsening despite improving CD4/viral load
Biggest risk factor	CD4 <50 cells/μL at ART initiation
Most common triggers	M. tuberculosis, MAC, Cryptococcus, PCP
Most dangerous manifestation	Cryptococcal meningitis-IRIS (CNS, high mortality)
Prevention (TB-IRIS)	Prophylactic prednisone (PredART protocol)
Prevention (Crypto-IRIS)	Delay ART 4-5 weeks; CrAg screening
Treatment backbone	Continue ART + steroids for severe cases

This is a shared conversation. Sign in to Orris to start your own chat.