Question 1: (Amani) It is very important that doctors, researchers and patients understand the terminology used to define allergic diseases. Failure to do so may result in inappropriate advice, prevention, and ineffective treatments. The term allergy commonly refers to reactions or conditions related to an immunological mechanism mediated by IgE antibodies following antigen exposure. Antigen is a material capable of initiating an immune reaction when introduced into the human body (J.Genuis, 2010). Regarding food allergy, adverse food reactions (AFRs) can be classified into toxic and hypersensitivity reactions (HR). When an immunological response has occurred, the food hypersensitivity reaction should be defined as food allergy, while if the role of IgE is demonstrated, the appropriate definition is IgE-mediated food allergy. Approximately 20% of individuals report an AFR, while food allergy shows a lower prevalence: (0.5-3.8% in children and 0.1-1% in adults). (G. Gasbarrini, 2008). Non-toxic food reactions are classified into immunological (food allergies) and non-immunological (food intolerances); Food allergy is divided into: IgE mediated: characterized by the presence of specific IgE antibodies and the exact relationship between food ingestion and symptoms. and non-IgE mediated: demonstrated by antibodies of isotypes other than IgE: IgG, IgM, IgA which consists of cell-mediated immunity (Fig....). Hypersensitivity or sensitivity refers to reproducible symptoms or signs initiated by exposure to certain stimuli at a certain dose tolerated by normal people (SGO Johansson2004). The main differences between sensitivity and allergy are these; an allergy involved the immune system reaction, but s...... middle of paper ......t proteins to form covalent conjugates, so when penicillin is ingested or injected, it forms conjugates with proteins self, and penicillin modified self peptides cause a TH2 response in some individuals. These TH2 cells then activate penicillin-binding B cells to produce IgE antibodies against the penicillin hapten. Therefore, penicillin acts both as a B-cell antigen and, by modifying self-peptides, as a T-cell antigen. While when penicillin is injected intravenously into an allergic patient, the proteins modified by penicillin can cross-link the IgE molecules on tissue mast cells and circulating basophils, thus causing anaphylaxis (A. Janeway, 2012)1-Haenuki Y, Matsushita K, Futatsugi-Yumikura S, Ishii KJ, Kawagoe T, Imoto Y, et al. A critical role of IL-33 in experimental allergic rhinitis. J Allergy Clin Immunol 2012;130:184-94.