were "empirical" until 1967 when Ishizaka identified IgE, the protein that is now associated with positive skin test reactions.[59] Within the year Wide, Bennich, and Johansson described a radioallergosorbent test (RAST) for identifying specific IgE antibodies.[151] The modified RAST system, developed by Nalebuff, Fadal, and Ali,[87] has since been adopted for its more precise diagnostic utility by many otolaryngologists and immunologists as an adjunct to IDT. These in-vitro tests have formed the basis of modern immunologic studies that confirm the validity of in-vivo testing and therapy. The efficacy of treating allergic disease with specific immunotherapy based on IDT has been confirmed by double blind placebo controlled studies and is now endorsed by immunologists.[27],[75]
One of the pitfalls of any study is the diagnosis of allergy. This quarter century has seen the advent of increasing standardization and quantification of allergy diagnostic testing based on the original works of Noon's prick test[90] in 1910. Hansel[49] proposed a method of intradermal testing (IDT) using a 10 fold serial dilution technique. This was further modified by Rinkel[108] who used a five-fold dilution that he believed more closely approximated skin sensitivity. Voorhorst described a preference for the intracutaneous method using a 1:3 dilution,[145] but the mathematics are more difficult. When low potency extracts are used, skin prick tests are less sensitive and reproducible than intradermal tests and in patients with a low sensitivity, intradermal tests may have the only positive results.[20]
Skin tests have a higher diagnostic sensitivity for symptomatic allergy than specific IgE or total IgE,[22] especially in food allergy testing.[63],[16] Prick test results correlate well with symptoms, although for patients with a low sensitivity intradermal skin tests have the only positive results.[29]
