Table 2.
Classification of Anaphylaxis According to Causative Mechanism
| Mechanism | Examples | Comments |
|---|---|---|
| Immunologic-IgE | Food allergensa | 8 common food allergens listed below |
| (Secondary MCD) | Airborne allergens | Animal dander, aerosolized foods, pollen |
| Latex | Gloves, catheters, masks, medication vials | |
| Hymenoptera venom | Honey bee, wasp, yellow jacket, hornet, IFA | |
| Medication allergy | Antibiotics, biologicals,b vaccines, NSAIDsb | |
| Alpha-gal | Mammalian meat (beef, pork, venison, lamb) | |
| FDEIA | Exercise + food (wheat, nuts, legumes, etc) | |
| Hormones | Progesterone or estrogens (catamenial) | |
| Seminal fluid | Postcoital anaphylaxis | |
| Radiocontrast mediab | IgE-mediated reactions have been reported | |
| Immunologic-non-IgE | Immune aggregates | Includes immune complexes/complement |
| IVIG | From IgG or IgE anti-IgA antibodies | |
| Aspirin and NSAIDsb | Leukotriene-driven and other mechanisms | |
| Dialysis membranes | ||
| Radiocontrast mediab | Complement activation, kinin generation | |
| Dextrans/HMW iron | ||
| Biologicsb | Cytokine inhibitors, omalizumab, etc | |
| Heparin | Generation of kinins by contaminated | |
| Chinese heparin | ||
| Nonimmunologic | ||
| Direct effects | Opiates, physical | Cold, heat, exercise, sunlight |
| Primary MCDc | MMAS and systemic | Genetic defects affect proliferation or activation of mast cells |
| MCASc | Can be associated with germline replications of TPSAB1 gene encoding α-tryptase36 | |
| Idiopathic | Increased mast cell sensitivity/degranulation | |
| T helper cell 2-cytokine polarization | ||
| Unrecognized allergens | ||
| Masqueraders | Munchausen stridor | |
| Undifferentiated somatoform anaphylaxis | ||
| Vocal cord dysfunction |
FDEIA = food-dependent exercise-induced anaphylaxis; HMW = high molecular weight; IFA = imported fire ant; IVIG = immunoglobulin, intravenous; MCD = mast cell activating disorder; MMAS = monoclonal mast cell activation syndrome; MCAS = mast cell activation syndrome; NSAID = nonsteroidal antiinflammatory drugs; TPSAB1 = tryptase alpha/beta 1 (human).
a
Both IgE-mediated and non-IgE-mediated reactions have been reported.
b
Milk, egg, wheat, soy, tree nuts, peanut, shellfish, and fin fish are commonly incriminated.
c
Mast cell disorders are associated with both IgE-mediated allergic reactions as well as spontaneous mast cell degranulation.36