THE MEANING OF ALLERGY: SKIN-PRICK TEST
April 20th, 2009Henceforth, a disease could only be described as an allergy if the immune system was demonstrably involved.
The way to demonstrate immune system involvement was by a skin-prick test. This involved making a purified extract of the allergen. A small amount of the extract was then inserted under the skin, by scratching or pricking it. If the area came up in a bump with a large area of red itchy skin around it, then an immune reaction had occurred.
It had become clear that patients with certain diseases were likely to give positive skin-prick tests. These diseases were hay-fever, asthma (breathlessness with wheezing episodes), and non-seasonal or perennial rhinitis (constant runny or congested nose). Also linked with positive skin-prick tests, although to a lesser extent, were urticaria or hives (a rash that resembles nettle-stings) and one type of eczema (areas of red, itchy, flaky skin). Moreover, these five disorders often seemed to go together, either in individuals or in families.
These became the only legitimate subjects for study as far as orthodox allergists were concerned, and they are still described as the classical allergic disorders. Included in their ranks was a type of reaction to food that was very violent and came on rapidly after eating the allergen, often within minutes. The symptoms produced included swelling of the lips, mouth and tongue, urticaria (nettle-rash), vomiting and, in severe cases, collapse or anaphylactic shock – the reaction that Jane experienced when she ate peanuts in the restaurant cheesecake. In these cases, too, there was almost always a positive reaction to a skin-prick test with the suspect food.
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