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Patterson’s Allergic Diseases: Part 2

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(BQ) If you are reading this book, then you probably already take care of neurology patients. This also means that you already realize that neurology is a challenging specialty. Lack of knowledge regarding how to perform an adequate neurological examination, how to diagnose specific conditions, and, perhaps most importantly, how to treat them, can be dangerous for both the patient and provider. | Patterson s Allergic Diseases Part 2 Hypersensitivity pneumonitis HP also known as extrinsic allergic alveolitis is a multifaceted immunologically mediated pulmonary disease with associated constitutional symptoms as a result of sensitization and then repeated inhalation of a wide variety of inhaled organic dusts. It is characterized by non immunoglobulin E IgE -mediated inflammation of the pulmonary interstitium terminal airways and alveoli. This syndrome occurs in both atopic and nonatopic individuals and may present in several clinical forms depending on the duration frequency and intensity of antigen exposure the antigenicity of the offending agent and the patient s age and immunologic responsiveness. Most cases occur in occupational and agricultural settings. However various hobbies and medications are also associated with HP. Despite the many antigens recognized to cause HP the clinical immunologic and pathophysiologic findings are generally comparable. ALLERGENS OF HYPERSENSITIVITY PNEUMONITIS 1161 HP was recognized by Ramazzini 1 in 1713 in grain workers. Because awareness of this pulmonary disease has increased there has been identification of new antigens implicated in the disease currently encompassing over 200 different agents 2 . Although the immunopathophysiology of the disease is becoming clarified there continue to be cases of HP in which the specific antigen has not been defined. The primary exposures for the development of HP are occupational agricultural and those related to hobbies. To reach the terminal airways and alveoli the allergenic particles must be smaller than 3 to 5 μm. The variety of causative antigens includes airborne microbial antigens animal or plant products and low-molecular-weight chemicals Table 23.1 . Many of these same antigens such as diisocyanates mammalian and insect proteins and wood dusts can also induce IgE mast cell-mediated allergic responses including asthma. Thermophilic actinomycetes were recognized as the .