Antigen Desensitization
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More Specific Terms
Indications
- symptoms that occur after natural exposure to the allergen
- demonstrable IgE antibodies against the antigen
- antigen is not easily avoided
- trial of medical therapy has failed
- anaphylactic reaction to hymenoptera venom
Principle
- prevents anaphylaxis by favoring formation of univalent haptens
- univalent haptens can bind IgE on surface of mast cells but do NOT cause cross-linking & degranulation
- similar in principle to homeotherapy
Clinical-significance
- Effects of immunotherapy on allergic reactions:
- production of IgG antibodies against allergen
- reduction in IgE response after allergen exposure
- increased allergen-specific IgG & IgA in respiratory secretions
- reduced release of mediators by allergen-challenged basophils (derived from peripheral blood)
- changes in cytokine production by T-helper lymphocytes
- induction of anergy in allergen-responsive T-helper lymphocytes
- certain fragments of allergens down-regulated T-helper activity but do not stimulate release of mediators by mast cells
- may evenually form new approach to allergen immunotherapy
- Specific agents:
- NSAIDs
- desensitization to aspirin produces cross-desensitization to all NSAIDs
- sensitization persists for 2-7 days after each dose
- interruption of NSAIDs for > 48 hours requires repeat desensitization
Procedure
- intravenous & oral protocols
- should be performed by experienced personelle in an intensive care unit ( ICU) setting
- avoid premedication with antihistamines & glucocorticoids
- drug desensitization for sulfonamides may be performed on an outpatient basis
More General Terms
Additional Terms
References
- Medical Knowledge Self Assessment Program (MKSAP) 11, American College of Physicians, Philadelphia 1998
- National Guideline Clearinghouse Allergen immunotherapy: a practice parameter second update ngc-guideline: [1]
