| Disease | Potential mechanisms |
| Atopic diseases | Allergen-specific IgE |
| Chronic autoimmune urticaria | Anti-IgE or anti-Fc-epsilon-RI autoantibodies |
| Autoimmunity | IgG receptor, complement |
| Chronic infections | TLRs, IgG, complement |
| Drug allergy | Specific receptors, complement, IgE |
| Physical stimuli | Direct mast cell activation |
| Neoplasms | Complement, cytokines |
