Essentials of Allergy M Thirumala Krishna PhDMRCP(UK)DNB Specialist Registrar in Allergy and Clinical Immunology, and Honorary Clinical Lecturer, Southampton General Hospital and University of Southampton, Southampton, UK George Mavroleon PhD Specialist in Allergy, 10–12 Sfakion Street, Chania, 73134 Crete,Greece Stephen T Holgate MDDScFRCP MRCClinical Professor of Immunopharmacology, andHonorary Consultant Physician, University of Southampton and Southampton General Hospital, Southampton, UK with a Foreword by Professor Stephen R Durham MAMDFRCP, Professor of Allergy and Respiratory Medicine, National Heart & Lung Institute, London, UK MARTIN DUNITZ Although every effort is made to ensure that drug doses and other information are presented accurately in this publication, the ultimate responsibility rests with the prescribing physician. Neither the publishers nor the authors can be held responsible for errors or for any consequences arising from the use of information contained herein. © 2001 Martin Dunitz Ltd, a member of the Taylor and Francis group This edition published in the Taylor & Francis e-Library, 2003. First published in the United Kingdom in 2001 by Martin Dunitz Ltd The Livery House 7–9 Pratt Street London NW1 0AE Tel: (cid:1)44-(0)20-7482-2202 Fax: (cid:1)44-(0)20-7267-0159 E-mail: [email protected] Website: http://www.dunitz.co.uk All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior permission of the publisher or in accordance with the provisions of the Copyright Act 1988. A CIP catalogue for this book is available from the British Library ISBN 0-203-21315-7 Master e-book ISBN ISBN 0-203-27023-1 (Adobe eReader Format) ISBN 1-85317-783-0(Print Edition) Distributed in the United States by: Blackwell Science Inc. Commerce Place, 350 Main Street Malden MA 02148, USA Tel: 1-800-215-1000 Distributed in Canada by: Login Brothers Book Company 324 Salteaux Crescent Winnipeg, Manitoba R3J 3T2 Canada Tel: 1-204-224-4068 Distributed in Brazil by: Ernesto Reichmann Distribuidora de Livros, Ltda Rua Coronel Marques 335, Tatuape 03440-000 Sao Paulo Brazil Composition by Wearset, Boldon, Tyne and Wear Cover image: Dr Brian Eyden/Science Photo Library. Contents Foreword v Preface vii 1 Diagnostic tests in allergy 1 2 Asthma 15 3 Rhinitis 29 4 Urticaria and angioedema 53 5 Anaphylaxis 77 6 Insect venom allergy 85 7 Drug allergy 95 8 Food allergy 107 9 Atopic dermatitis (eczema) 129 10 Immunotherapy 145 11 Latex allergy 161 12 Eosinophilic lung diseases 167 13 Extrinsic allergic alveolitis 181 Index 191 Foreword Atopy, a predisposition to IgE-mediated allergic disorders, is defined as the presence of a positive skin test and/or raised serum allergen-specific IgE to one or more common inhaled allergens. Atopy affects some 30–40 per cent of the population of westernised countries. Approximately half these individuals develop clinically significant allergic disorders, which include allergic rhinitis, conjunctivitis and bronchial asthma. Allergic rhinitis is particularly common and, although often trivialized, may have a major impact on quality of life with impaired performance at work/school, poor sleep quality and interference with leisure pursuits. Less common but potentially life-threatening conditions include anaphylaxis to certain foods and to the venom of stinging insects. Essentials of Allergycovers the diagnosis and clinical management of the common allergies. The less common eosinophilic lung diseases and extrinsic allergic alveolitis are also expertly covered. The text is easy to read and complemented by the many tables and illustrations. The diagnostic algorithms and detailed information on drugs vi Foreword and doses are particularly helpful. particular interest to general practitioners, Frequently, allergic disorders coexist. nurses and organ-based specialists and Whereas the first port of call for patients will be a valuable teaching aid for with multiple allergies is, quite rightly, the allergists. general practitioner, such patients may benefit from the multidisciplinary Professor Stephen R Durham approach offered by an allergy specialist. Professor of Allergy and Respiratory In this sense, Essentials of Allergy‘fills Medicine the gap’ by providing a timely and Upper Respiratory Medicine comprehensive account of the common National Heart & Lung Institute allergic disorders. The book should be of London Preface Most medical specialties are focused on specific organs, while others, such as immunology, cover a series of interdependent events relating to the host and its ability to protect itself against the environment. The practice of allergy falls somewhere between the two: strong organ- based expression (e.g. asthma, atopic eczema) but often extending to other systems. The definition of ‘allergy’ also leads to confusion – on the one hand, meaning a group of hypersensitivity disorders with well-defined immunological mechanisms and, on the other, covering a range of intolerances to various environmental factors for which clear mechanisms have not been defined. Different health systems provide services to allergy patients through both the primary and secondary care sectors, with large variations between countries. Because of the high prevalence of allergic disease, its rising trend over time and the appearance of new allergens to which patients react, we felt there was a need for an easily digestible text on the subject, which was highly accessible to those wishing to obtain a good background relatively easily. We have targeted the book viii Preface towards both primary and secondary There is a pressing need to improve the health care. The text is divided into 13 quality of care that patients with allergic chapters covering different aspects of disease receive. It is with this in mind that hypersensitivity responses. Thus, the we hope that this text provides a useful book is clinically oriented and should be and accessible source of practical valuable to trainees in allergy, respiratory information. medicine and general (internal) medicine, as well as to general practitioners and the MThirumala Krishna professions allied to medicine. George Mavroleon Stephen T Holgate 1 Diagnostic tests in allergy 1 Introduction Although there is no substitute for a good history in clinical medicine, laboratory tests are often required to strengthen the clinical diagnosis and to provide a means of, objectively, evaluating the disease, its severity and its response to treatment. This chapter focuses on various in vivoand in vitrotests employed in the investigation and diagnosis of allergic disease. Some of these tests are used mostly as research tools but, nevertheless, they provide useful clinical information. In vivo tests Skin prick tests Skin prick tests (SPT) (Figure 1.1) have been, and will remain, the gold standard in the diagnosis of allergy. The basic principle of this test is to detect the presence of specific IgE bound to the surface of mast cells and basophils. Upon challenge with the allergen, there is cross-linking between the specific IgE and allergen on