How are mast cells triggered?

➢ Many diseases can be caused by non-specific, IgEindependent mast cell activation, which might be considered as subtype of type I HS reaction ➢ Mast cells may be triggered by other stimuli such as – Exercise, – Emotional stress, – Chemicals, – Drugs (iodinated contrast media, biologic medicines, opiates,…) – Anaphylotoxins (e.g., C4a, C3a, C5a, etc.). ➢ These reactions are not HS reactions although they produce the same symptoms.