New visions for basic research and primary prevention of pediatric allergy: An iPAC summary and future trends The optimal management of allergies is to prevent them from becoming clinically expressed by efficient primary prevention. Although a set of primary preventive measures, in large part with- out clear scientific validation, have been applied for several decades, the rate of allergic diseases has steadily increased over the years (1). Efficient primary prevention is largely hampered by our patchy understanding of immune events in early life. We need to link laboratory studies on the early maturation of the immune system with clinical research projects focusing on the efficient primary prevention of allergy more closely. The aim of this review is to provide a state-of-the-art review linking early events influencing the immune system and clinical studies on primary prevention, as well as a prospective for future research. The immune system with regard to allergy is relatively naı¨ve in the newborn child. Although primary sensitization can occur during preg- nancy or lactation, newborns and young infants Hamelmann E, Herz U, Holt P, Host A, Lauener RP, Matricardi PM, Wahn U, Wickman M. New visions for basic research and primary prevention of pediatric allergy: An iPAC summary and future trends. Pediatr Allergy Immunol 2008: 19 (Suppl. 19): 4–16. Ó 2008 The Authors Journal compilation Ó 2008 Blackwell Munksgaard Hydrolyzed formula feeding, delayed introduction of solid food, indoor allergen avoidance, smoke and pollutants avoidance have been applied for several decades as primary preventive measures for allergic diseases. Unfortunately, some of these strategies have had no or modest success. Therefore, resources need to be focused on better understanding of the early allergic events and on interventional studies to investigate new strategies of primary and secondary prevention. Accordingly, this re- view summarizes the state-of-the-art of genetic, immunological and clinical aspects of primary prevention of allergic diseases. Studies investigating gene-by-gene and gene-by-environment interactions sug- gest that prevention of allergic diseases must be tailored to the indi- vidual genetic susceptibilities (Ôgene profilingÕ) and environmental exposures. The expanding knowledge on new T cell populations (Th17, TSLP (thymic stromal derived lymphopoietin)-dependent Ôinflamma- tory Th2 cellsÕ) is also inspiring new concepts on the origins of allergic diseases. The old concept of Ôblocking immunoglobulin G antibodiesÕ has been re-appraised and it is likely to generate novel preventive and therapeutic strategies. The major task for future clinical research is to clearly define the timing of optimal exposure to potential allergens. In addition, the role of microbial products such as certain bacteria, or their components, and of helminths or their larvae at different times in early life, alone or with potential allergens, definitely need to be further investigated. The benefit of efficient allergy prevention, based on focusing resources on novel and promising research lines, will be of prime importance to both affluent countries and other parts of the world where allergy is only currently emerging. Eckard Hamelmann 1,2 , Udo Herz 3 , Pat Holt 4 , Arne Host 5 , Roger P. Lauener 6 , Paolo M. Matricardi 2 , Ulrich Wahn 2 and Magnus Wickman 7 1 Children's Hospital of Ruhr University, Bochum, 2 Department of Pediatric Pneumology and Immunology, University Children's Hospital CharitØ of Humboldt University, Berlin, Germany, 3 Mead Johnson, Nutritionals, Bristol-Myers Squibb, Evansville, USA, 4 Telethon Institute for Child Health Research, University of Western Australia, Perth, Australia, 5 H.C. Andersen Children's Hospital, Odense University Hospital, Odense, Denmark, 6 Children's Hospital, University of Zurich, Switzerland, 7 Sachs Children's Hospital and Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden Key words: immunology; allergy; genetics; prevention; immunotherapy Eckard Hamelmann, Klinik für Kinder- und Jugendmedizin, der Ruhr-Universität Bochum im St. Josef-Hospital, Alexandrinenstraße 5, 44791 Bochum Tel.: +49 234 509 2611 Fax: +49 234 509 2612 E-mail: eckard.hamelmann@klinikum-bochum.de Conflict of Interest: U.H. is an employee of Mead Johnson Nutritionals, a Bristol Myers-Squibb company; all remaining authors declare no conflict of interests. Accepted 28 April 2008 Pediatr Allergy Immunol 2008: 19 (Suppl. 19): 4–16 DOI: 10.1111/j.1399-3038.2008.00763.x Ó 2008 The Authors Journal compilation Ó 2008 Blackwell Munksgaard PEDIATRIC ALLERGY AND IMMUNOLOGY 4