[Allergy and Immunology in the 21st Century - from Symptomatic Treatment to Precision Medicine]

This issue of Harefuah is dedicated to the field of Allergy and Immunology (A/I). Many aspects in the field have undergone complete transformation in recent years, and here we highlight "hot topics" at the forefront of the field. These topics are not only relevant to those practicing A/I, but are often encountered by other physician in their respective fields. A classic example is penicillin allergy. The approach to penicillin allergy has changed beyond recognition, from extensive evaluation including allergy tests, to a quick de-labeling approach in most patients. In the case of food allergy, the implications extend far beyond clinical work and impact public policy. Several articles in this issue address recent developments in the field of food allergy, clarifying misconceptions and presenting up to date recommendations regarding both primary prevention and treatment. The development of new drugs in recent years has led to breakthroughs in the understanding and management of many diseases in A/I, as presented in the papers discussing mast cell activation syndrome (MCAS), eosinophilic diseases (with emphasis on hypereosinophilic syndrome and eosinophilic granulomatosis with polyangiitis), and hereditary angioedema. New classifications, based on better understanding of their pathophysiology, together with the development of novel drugs, have completely transformed the course and prognosis of these diseases. Finally, the issue includes several articles providing new insights into immunodeficiency disorders. The field of primary immunodeficiency which is now termed "Inborn Errors of Immunity (IEI)", has evolved dramatically in recent years. This includes the realization that IEI do not necessarily present as recurrent infections, but rather can present with a variety of clinical manifestations including autoimmunity, atopy, and even malignancy. In fact, IEI are now identified in diseases previously not perceived as immunodeficiencies. We hope that this issue will provide better understanding of the field of A/I, and assists every physician who encounters these diseases within their practice.