Is food desensitization (oral immunotherapy, OIT) possible for a patient with a severe shellfish allergy to prawns?

Oral Immunotherapy for Severe Prawn Allergy

Oral immunotherapy (OIT) is possible for severe prawn allergy but should only be conducted in highly controlled clinical settings under specialist supervision due to significant risk of anaphylaxis. 1

Current Status of Shellfish OIT

• OIT for shellfish allergies, including prawns, is still considered investigational and is not recommended for routine clinical practice according to multiple guidelines 1
• While OIT can effectively desensitize many individuals with food allergies, the safety profile and long-term efficacy specifically for shellfish allergies remain limited 2
• Shellfish OIT presents unique challenges including taste, odor, unclear cross-reactivity patterns, and protein alterations during cooking processes 2

Mechanism of Action

• OIT works by gradually exposing the immune system to increasing amounts of the allergen (prawns), promoting regulatory T-cell development 1
• The process induces immunological changes including:
  • Initial increase in allergen-specific IgE followed by eventual decrease below baseline 3
  • Gradual increase in allergen-specific IgA and IgG4 throughout treatment 3
  • Development of basophil hyporesponsiveness and decreased skin reactivity 3

OIT Protocol Structure

• OIT protocols typically involve three phases 4, 5:

  1. Initial dose escalation: Starting with extremely small amounts of prawn protein in a controlled setting
  2. Build-up phase: Gradually increasing doses under medical supervision
  3. Maintenance phase: Regular consumption of a target dose to maintain desensitization

• Most protocols begin with sublingual exposure before progressing to oral consumption 5

Safety Considerations

• Anaphylaxis is a significant risk during OIT, requiring immediate access to epinephrine 6
• Systemic reactions can occur even at previously tolerated doses, particularly during illness or exercise 1
• The American Academy of Allergy, Asthma, and Immunology emphasizes that epinephrine (0.3-0.5 mg for adults) must be immediately available during all OIT procedures 6
• Patients undergoing OIT must have an emergency action plan and carry epinephrine auto-injectors 1, 6

Efficacy Expectations

• Approximately 85% of patients may successfully complete food desensitization protocols 5
• Most patients achieve desensitization (protection while on therapy) rather than sustained unresponsiveness (protection after stopping therapy) 4, 7
• Immunological changes during successful OIT include decreased specific IgE and increased specific IgG4 5

Adjunctive Therapies

• Anti-IgE therapy (omalizumab) may improve safety and accelerate desensitization during OIT 1
• For patients with multiple food allergies, multi-food OIT protocols with omalizumab have shown promising results 1

Practical Considerations

• OIT for prawns should only be performed by specialists with experience in food allergy immunotherapy 2
• The process requires multiple clinic visits over many months to years 1
• Patients must be highly motivated and understand the risks, benefits, and time commitment 2
• Regular monitoring of immunological parameters may help track progress 5, 3

Pitfalls and Limitations

• OIT does not typically result in a permanent cure - most patients require ongoing exposure to maintain desensitization 7, 3
• Discontinuation of therapy often results in return of sensitivity 4
• Long-term safety and efficacy data for shellfish OIT specifically are lacking 2
• Quality of life may improve but must be balanced against treatment burden and ongoing risk 1

Finding OIT Treatment

• As shellfish OIT is investigational, patients should seek specialized allergy centers conducting clinical trials 1
• In some regions, OIT protocols must be approved by ethics committees and administered with informed consent 1
• Patients should be carefully screened for suitability, including assessment of asthma control and other risk factors 6, 8