The availability of allergen molecules ('components') from several protein families has advanced our understanding of immunoglobulin E (IgE)-mediated responses and enabled 'component-resolved diagnosis' (CRD). The European Academy of Allergy and Clinical Immunology (EAACI) Molecular Allergology User's Guide (MAUG) provides comprehensive information on important allergens and describes the diagnostic options using CRD. Part A of the EAACI MAUG introduces allergen molecules, families, composition of extracts, databases, and diagnostic IgE, skin, and basophil tests. Singleplex and multiplex IgE assays with components improve both sensitivity for low-abundance allergens and analytical specificity; IgE to individual allergens can yield information on clinical risks and distinguish cross-reactivity from true primary sensitization. Part B discusses the clinical and molecular aspects of IgE-mediated allergies to foods (including nuts, seeds, legumes, fruits, vegetables, cereal grains, milk, egg, meat, fish, and shellfish), inhalants (pollen, mold spores, mites, and animal dander), and Hymenoptera venom. Diagnostic algorithms and short case histories provide useful information for the clinical workup of allergic individuals targeted for CRD. Part C covers protein families containing ubiquitous, highly cross-reactive panallergens from plant (lipid transfer proteins, polcalcins, PR-10, profilins) and animal sources (lipocalins, parvalbumins, serum albumins, tropomyosins) and explains their diagnostic and clinical utility. Part D lists 100 important allergen molecules. In conclusion, IgE-mediated reactions and allergic diseases, including allergic rhinoconjunctivitis, asthma, food reactions, and insect sting reactions, are discussed from a novel molecular perspective. The EAACI MAUG documents the rapid progression of molecular allergology from basic research to its integration into clinical practice, a quantum leap in the management of allergic patients.

KEYWORDS food allergy • food intolerance • IgG • IgG4 • in vitro tests ABSTRACTSerological tests for immunoglobulin G4 (IgG4) against foods are persistently promoted for the diagnosis of food-induced hypersensitivity. Since many patients believe that their symptoms are related to food ingestion without diagnostic confirmation of a causal relationship, tests for food-specific IgG4 represent a growing market. Testing for blood IgG4 against different foods is performed with large-scale screening for hundreds of food items by enzyme-linked immunosorbent assay-type and radioallergosorbent-type assays in young children, adolescents and adults. However, many serum samples show positive IgG4 results without corresponding clinical symptoms. These findings, combined with the lack of convincing evidence for histamine-releasing properties of IgG4 in humans, and lack of any controlled studies on the diagnostic value of IgG4 testing in food allergy, do not provide any basis for the hypothesis that food-specific IgG4 should be attributed with an effector role in food hypersensitivity. In contrast to the disputed beliefs, IgG4 against foods indicates that the organism has been repeatedly exposed to food components, recognized as foreign proteins by the immune system. Its presence should not be considered as a factor which induces hypersensitivity, but rather as an indicator for immunological tolerance, linked to the activity of regulatory T cells. In conclusion, food-specific IgG4 does not indicate (imminent) food allergy or intolerance, but rather a physiological response of the immune system after exposition to food components. Therefore, testing of IgG4 to foods is considered as irrelevant for the laboratory work-up of food allergy or intolerance and should not be performed in case of food-related complaints. ARTICLE TEXTAn adverse food reaction is a general term describing clinically abnormal responses to an ingested food that might occur secondary to nonallergic food hypersensitivity (food intolerance) or allergic food hypersensitivity (food allergy).Food allergy is an immunologic reaction that involves in particular the immunoglobulin E (IgE) mechanism, of which anaphylaxis is the classic example.Food intolerance, however, is a general term, describing an abnormal physiologic response to an ingested food or food additive. Diagnosis of food allergy aims to establish a reliable link between the clinical history of an adverse reaction to food as reported by the patient and the immunological basis of this reaction. In food allergy, an accurate diagnosis is extremely important, in particular to prevent patients from unnecessary and even potentially health threatening diets.Measurement of food-specific IgE antibodies by in vitro assays or skin testing are the routine procedures to diagnose food allergy. These diagnostic tests, however, indicate the presence of food-specific IgE antibodies, but they do not establish the diagnosis of food allergy. The final proof of the clinical relevance of the reported

Food allergy is associated with higher health care costs. Severity of allergic symptoms is a key explanatory factor.

Buckwheat allergy is an emerging food allergy in Italy. We identified three distinct patterns of clinical and laboratory characteristics, suggesting that specific allergens could be more frequently associated with clinical manifestations of different severity.

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Background: Polcalcins are highly cross-reactive pollen panallergens. Less than 10% of allergic patients are sensitized to polcalcins. All pollen species are considered able to sensitize patients to this panallergen. Objective: We aimed to assess the presence of polcalcins in various pollen extracts used in allergen immunotherapy. Methods: ELISA inhibition experiments were performed with sera from patients sensitized to polcalcin and rPhl p 7 and rBet v 4. Recombinant polcalcin was used as the substrate and freshly prepared pollen extracts as inhibitors. Results: All pollen extracts induced significant inhibition of IgE reactivity to rBet v 4, whereas only grass pollen extract induced marked inhibition of IgE reactivity to rPhl p 7. Conclusion: Grass polcalcin probably contains more epitopes than polcalcins from other pollen sources. Grass pollen could be responsible for sensitization to polcalcins, and grass pollen immunotherapy is likely to be an option for polcalcin-hypersensitive patients.

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The families of seed storage proteins, together with profilins, oil-bodies-associated oleosins, and pathogenesis-related (PR) proteins like PR-10 (Bet v 1-like), PR-12 (defensins) and PR-14 (non-specific lipid transfer protein), are the main causes of IgE sensitization to tree nuts, legumes and seeds. All these allergens, with the exclusion of profilins and of PR-10, are heat-stable and possibly responsible for fatal or almost fatal adverse reactions to such foods. In this short review, we will discuss the relationship and amino acid identities among some of the seed storage homologue molecules identified to date from tree nuts, seeds and legumes.