Immunology · Year 2 · from Immunology
Case 3: Selective IgA Deficiency with Transfusion Reaction
Patient Demographics
- Age: 45 years old
- Sex: Female
- Ethnicity: Caucasian
Chief Complaint
Severe reaction during blood transfusion
History of Present Illness
A 45-year-old woman with a history of menorrhagia and iron deficiency anemia unresponsive to oral iron presents for elective hysterectomy. Preoperative hemoglobin was 8.5 g/dL. During surgery, she received 2 units of packed red blood cells. Approximately 15 minutes into the second unit, she developed urticaria, wheezing, hypotension (BP 70/40), and tachycardia. The transfusion was stopped immediately. She required epinephrine, fluids, and steroids for stabilization.
Past Medical History
- Iron deficiency anemia (5 years)
- Recurrent sinusitis (2-3 episodes per year)
- History of "allergic reaction" to blood transfusion 10 years ago during cesarean section
- Celiac disease (diagnosed 3 years ago)
- Autoimmune thyroiditis
Family History
- Daughter with celiac disease
- No known immunodeficiency
Physical Examination (Post-reaction, stabilized)
- General: Anxious but stable
- Vital Signs: T 37.2C, HR 95, RR 18, BP 110/70 (after treatment)
- Skin: Resolving urticaria on trunk and extremities
- Lungs: Mild scattered wheezes
- Cardiovascular: Regular rhythm, no murmurs
Laboratory Workup
| Test | Result | Reference Range |
|---|---|---|
| IgA | <5 mg/dL | 70-400 mg/dL |
| IgG | 1050 mg/dL | 700-1600 mg/dL |
| IgM | 120 mg/dL | 40-230 mg/dL |
| Anti-IgA antibodies | Positive (IgE and IgG class) | Negative |
| Tryptase (during reaction) | 25 ng/mL | <11 ng/mL |
| Direct antiglobulin test | Negative | Negative |
| Hemoglobin (post-transfusion) | 8.8 g/dL | 12-16 g/dL |
Clinical Image
Image showing urticarial reaction pattern that can occur during anaphylactic transfusion reactions. Image source: Wikimedia Commons (https://commons.wikimedia.org/wiki/File:EMminor2010.JPG). Licensed under CC BY-SA 3.0.
Diagnosis
Selective IgA Deficiency with anti-IgA antibody-mediated anaphylactic transfusion reaction.
Discussion
Selective IgA deficiency is the most common primary immunodeficiency, affecting approximately 1:500 individuals of European descent. It is defined as:
- Serum IgA <7 mg/dL
- Normal IgG and IgM
- Age >4 years (to exclude developmental delay)
Clinical spectrum:
- Most patients are asymptomatic (85-90%)
- Increased upper and lower respiratory infections
- GI infections, Giardia susceptibility
- Associated autoimmune diseases (celiac disease, autoimmune thyroiditis, SLE)
Transfusion reactions:
- Some IgA-deficient patients develop anti-IgA antibodies
- IgE class anti-IgA antibodies can cause anaphylaxis when exposed to IgA in transfused blood products
- Risk is estimated at 1:20,000-1:50,000 transfusions in IgA-deficient patients
Why did the second transfusion cause the reaction?
- The first unit may have provided sensitization or boosted existing anti-IgA
- Anaphylaxis occurred when more IgA was introduced with the second unit
- Her previous "allergic reaction" during C-section was likely the same mechanism
Treatment
- Acute anaphylaxis management: Epinephrine, antihistamines, steroids, fluids
- Future transfusions:
- Use IgA-deficient blood products (from IgA-deficient donors)
- If unavailable, use washed cellular blood products (removes plasma IgA)
- Premedication with antihistamines/steroids is NOT sufficient alone
- Medical alert: Patient should wear medical alert identification
- IVIG is contraindicated: Standard IVIG contains IgA; if Ig replacement needed, must use IgA-depleted products
- Monitor associated conditions: Celiac disease, autoimmune thyroiditis
- No specific treatment for IgA deficiency itself: Ig replacement not indicated unless concomitant IgG subclass deficiency with recurrent infections