tailieunhanh - Ebook The Washington Manual allergy, asthma and immunology (2nd edition): Part 2

(BQ) Part 2 book "The Washington Manual allergy, asthma and immunology" presents the following contents: Urticaria and angioedema, atopic dermatitis, allergic contact dermatitis, ocular allergic disease, anaphylaxis, drug allergy and desensitization, insect allergy, food allergy and other adverse food reactions, latex hypersensitivity,. | Advantages of skin tests Most sensitive in detection of antigen-specific IgE Results available in minutes Greater selection of allergens Cheaper than in vitro tests Minimal equipment needed Advantages of in vitro tests No risk of anaphylaxis Not affected by medications Can be used on patienfs with skin conditions that would preclude skin testing Convenient for patients afraid of needles Perceived by patients as more scientific In Vitro Methods of Detecting Antigen-specific IgE Antigen-specific IgE can also be detected using laboratory Advantages and disadvantages of in vivo . skin testing see above and in vitro allergy testing can be found in Table 2 All in vitro tests of antigen-specific IgE use the principle of immunoadsorption. First the antigen in question is bound to a solid phase . a paper disk cellulose sponge or plastic microtiter well plate . A patient s serum is incubated with the solid phase. After washing a labeled anti-human IgE is incubated with the solid phase. After another washing the amount of labeled anti-IgE is measured and reported either in absolute IgE units or as a class score. A class score of 0 is negative scores in the range 0-1 are considered indeterminate and any score 2 is considered positive and should be correlated with clinical history. Older methods used radiolabeled reagents to quantify absorbed antigenspecific IgE. This method is called radioallergosorbent test RAST a term that is still used to refer to any method of in vitro quantitation of antigen-specific IgE. Radiologic methods for quantitation of antigen-specific IgE have been largely replaced by fluorescence-based methods. Diagnostic Testing for Allergic Contact Dermatitis Patch Testing The patch skin test is the most useful tool in identifying the cause of allergic contact Unlike epicutaneous and intradermal skin testing patch testing is a measure of a delayed hypersensitivity reaction or a cell-mediated hypersensitivity 2 .