Can lupus cause anaphylactic-like reactions?

Can Lupus Cause Anaphylactic-Like Reactions?

Yes, systemic lupus erythematosus (SLE) can cause anaphylactic-like reactions, though true IgE-mediated anaphylaxis is not a typical manifestation of lupus itself. Rather, patients with SLE have a higher predisposition to allergic disorders and drug hypersensitivity reactions that can present with anaphylactic-like features.

Relationship Between SLE and Allergic/Anaphylactic Reactions

Increased Prevalence of Allergic Disorders in SLE

• Studies have consistently shown that patients with SLE have a significantly higher prevalence of allergic disorders compared to the general population:
  • 63% of SLE patients have at least one type of allergic disorder versus 30% in control groups 1
  • 76% of SLE patients report allergic manifestations compared to only 37% of patients with other autoimmune diseases 2
  • Drug allergies are particularly common in SLE patients (38% vs 17% in controls) 1

Mechanisms Behind Anaphylactic-Like Presentations in SLE

Several mechanisms may explain the anaphylactic-like reactions in lupus patients:

1. Immune Dysregulation: The underlying immune dysregulation in SLE may increase susceptibility to IgE-mediated allergic disorders 3

2. Complement Activation: Anaphylactoid reactions can occur through activation of the complement system, which is frequently dysregulated in SLE 2

3. Cytotropic Autoantibodies: SLE-related autoantibodies may trigger mast cell activation and release of inflammatory mediators 2

4. Drug Hypersensitivity: SLE patients have a higher frequency of drug allergies (34.3%) compared to other rheumatic diseases like rheumatoid arthritis (18%) 4

Clinical Presentations

Anaphylactic-like reactions in SLE patients may present as:

• Skin manifestations (rash, urticaria) - most common presentation (73%) 4
• Respiratory symptoms (asthma, rhinitis)
• Cardiovascular involvement
• True anaphylaxis (less common but reported)

A case report documented a severe multisystem reaction in an SLE patient taking sulindac (an NSAID), which presented with features of an anaphylactoid reaction affecting cardiovascular, hepatic, pulmonary, and hematologic systems 5.

Diagnostic Considerations

When evaluating suspected anaphylactic-like reactions in SLE patients:

1. Determine if it's a true anaphylactic reaction:

   • Assess for cutaneous symptoms (urticaria, angioedema)
   • Evaluate respiratory compromise (wheezing, stridor)
   • Check for cardiovascular involvement (hypotension, tachycardia)
   • Consider GI symptoms (nausea, vomiting, diarrhea) 6

2. Consider laboratory testing:

   • Serum tryptase (15 min to 3 hours after reaction onset)
   • Urinary histamine metabolites (can be detected up to 24 hours) 6

3. Rule out differential diagnoses:

   • Vasodepressor (vasovagal) reactions
   • Panic attacks
   • Flushing syndromes
   • SLE disease flare 6

Management Approach

For anaphylactic-like reactions in SLE patients:

1. Acute Management:

   • Epinephrine (0.2-0.5 mL of 1:1000 solution) is first-line therapy for true anaphylaxis 6
   • Airway management and cardiovascular support as needed
   • H1 antihistamines for cutaneous symptoms
   • Corticosteroids may help prevent biphasic reactions

2. Prevention:

   • Identify and avoid triggers
   • Consider allergy testing for suspected drug allergies
   • Prescribe epinephrine auto-injectors for patients with history of severe reactions

3. Long-term Management:

   • Rheumatology consultation for optimal SLE control
   • Allergy/immunology consultation for evaluation of concurrent allergic disorders

Important Considerations

• Sulfa drugs are the most frequent cause of drug allergies in SLE patients 4
• NSAIDs are the second most common cause of drug-induced anaphylactic reactions in the general population and may pose particular risk in SLE patients 6
• The presence of allergic disorders in both SLE patients and their family members is significantly higher than in control groups, suggesting a genetic predisposition 1

Pitfalls and Caveats

• Normal levels of tryptase or histamine do not rule out anaphylaxis 6
• Beta-blockers and ACE inhibitors can increase the risk of anaphylactic reactions and may complicate management 6
• Distinguishing between an SLE flare and an allergic reaction can be challenging as both may present with constitutional symptoms
• Autoantibodies are often absent in drug-induced hypersensitivity reactions in SLE patients, making diagnosis more difficult 6

In conclusion, while lupus itself doesn't directly cause true IgE-mediated anaphylaxis, SLE patients have a higher predisposition to allergic and anaphylactic-like reactions through various immune mechanisms. Prompt recognition and appropriate management are essential to prevent serious outcomes.