Allergy Test (SPT) And Immunotherapy

Skin prick testing provides information about the presence of specific IgE to protein and peptide antigens (allergens). 

Small amounts of allergen are introduced into the epidermis and non-vascular superficial dermis and interact with specific IgE bound to cutaneous mast cells. Histamine and other mediators are released, leading to a visible “wheal-and-flare” reaction peaking after about 15 minutes.

There are three types of skin testing used in allergy diagnosis:

Skin prick testing (SPT) – the primary mode of skin testing for immediate IgE-mediated allergy. It is widely practiced, carries very low (but not negligible) risk of serious side effects to patients and provides high quality information when performed optimally and interpreted correctly. (Also called prick skin testing or PST).

Intradermal testing (IDT) – Relevant to both immediate IgE-mediated allergy and delayed-type hypersensitivity. When used in the diagnosis of immediate allergy, it carries a higher risk of adverse reactions and requires high levels of technical and interpretive expertise.

Patch testing – relevant to contact hypersensitivity and some other forms of delayed type hypersensitivity. It is conducted mainly by dermatologists and some immunologists, and is not relevant to immediate or IgE-mediated allergy, and will not be further discussed.