ABSTRACT
Antigen exposure with production of an immediate wheal and Oare in allergic individuals may lead to a prolonged inOammatory response known as the late-phase reaction (LPR) and also referred to as the dual-phase response. In 1873, Blackley (I), who was allergic to grass pollen, underwent a bout of sneezing and coryza lasting 6-8 h after pollen inhalation. On a different occasion, he accidentally inhaled a considerable quantity of pollen and developed nasal and systemic symptoms that lasted for many hours and prevented him from working for 2 days. Prausnitz and Klistner observed that the cutaneous inOammation associated with passive transfer of sensitivity lasted at least a day (2). In 1922, Cooke described a similar cutaneous reaction following exposure to horse dander (3). He developed a typical wheal and Oare followed by erythema and edema continuing into the following day. In 1924, Vaughn noted persistent inOammation at the site of skin tests (4). In 1952, Herxheimer stressed that the "late bronchial response" was "of great practical importance" and was associated with more severe asthma than the asthma in patients without late reactions (5). During the 1960s, Pepys and his colleagues called attention to dual skin reactions in patients with allergic aspergillosis and showed deposition of TgG, IgM, and C3 as well as marked tissue infiltration by neutrophils, suggesting an Arthus (Gell and Coombs type IfI) reaction as the mechanism
for prolonged inflammation. However, late reactions also occurred after skin testing with grass pollen extract (6), in which precipitating antibodies are uncommon, thus pointing away from a type III reaction.
