Have you ever been recommended for an allergy test by your doctor? If yes you’re probably familiar with skin prick tests and blood tests. If not, allergy tests are primarily ordered by doctors if their patient is having allergy symptoms: skin rash or hives, itchy skin, sneezing, stuffy or runny nose, sough, wheezing, ttchy and watery eyes, swelling of the face, lips, tongue or throat, difficulty breathing or swallowing, vomiting or diarrhea, and low blood pressure. Allergy tests allow doctors to develop allergy plans–immunotherapy– which usually involve allergy avoidance, allergy shots, and medicine. Like I mentioned before, diagnosing allergies mainly involve two tests: skin prick tests and blood tests. 

Skin Prick Tests: 

Like the name suggests, skin prick tests involve inserting a small amount of a substance into the skin by pricking it. After letting the substance sit for a couple of minutes, an elevated, red, itchy bump will either appear on the skin or it will look relatively the same. The substance that the skin is pricked with is called an allergen. An allergen is any substance that engenders an allergic reaction.  Skin prick tests can test a wide variety of allergens from as many as 50. After cleaning the skin with a alcohol swab, a lancet will be used to prick the skin. After 20 minutes the reactions will be evaluated, and the bumps typically go away after a few hours. Skin prick tests elicit response from the immune system, which is composed of a complex network of lymphoid organs and cells like lymphocytes, that are responsible for protecting the human body against infection. When someone is allergic to a subtance, their body would have already produce a type of antibody called immunoglobulin E (IgE) to protect the body. These antibodies are produced by white blood cells called B cells. During the skin prick test, it the person is allergic to an substance the allergen will bind to IgE antibodies which are already binded to mast cells and basophils. Mast cells are on the skin while basophils are in the blood, but they are both essenitally two types of immune cells.  This binding will trigger the production of histamine. Histamine, is responsible for the physical symptoms of allergic reactions. Histamine induces physical changes: blood vessels widening  and becoming porous, fluid escaping blood vessels (responsible for redness and swelling), production of mucus ( esponsible for congestion, runny nose, and teary eyes), stipulated nerve endings ( responsible for itching, rash, or hives),  and the production of more stomach acid.