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.

FOXP3+ regulatory T cells (Tregs) maintain tolerance against self-antigens and innocuous environmental antigens. However, it is still unknown whether Treg-mediated tolerance is antigen specific and how Treg specificity contributes to the selective loss of tolerance, as observed in human immunopathologies such as allergies. Here, we used antigen-reactive T cell enrichment to identify antigen-specific human Tregs. We demonstrate dominant Treg-mediated tolerance against particulate aeroallergens, such as pollen, house dust mites, and fungal spores. Surprisingly, we found no evidence of functional impairment of Treg responses in allergic donors. Rather, major allergenic proteins, known to rapidly dissociate from inhaled allergenic particles, have a generally reduced capability to generate Treg responses. Most strikingly, in individual allergic donors, Th2 cells and Tregs always target disparate proteins. Thus, our data highlight the importance of Treg antigen-specificity for tolerance in humans and identify antigen-specific escape from Treg control as an important mechanism enabling antigen-specific loss of tolerance in human allergy.

Background:The function of HtrA proteases in bacterial infections is widely unknown. Results: Secreted HtrA from various bacterial pathogens exhibits a conserved specificity for cleavage of E-cadherin. Conclusion: HtrA-mediated E-cadherin cleavage is a prevalent novel mechanism in bacterial pathogenesis. Significance: HtrA activity plays a direct role in the pathogenesis of different bacteria.

A systematic nomenclature for allergens originated in the early 1980s, when few protein allergens had been described. A group of scientists led by Dr. David G. Marsh developed a nomenclature based on the Linnaean taxonomy, and further established the World Health Organization/International Union of Immunological Societies (WHO/IUIS) Allergen Nomenclature Sub-Committee in 1986. Its stated aim was to standardize the names given to the antigens (allergens) that caused IgE-mediated allergies in humans. The Sub-Committee first published a revised list of allergen names in 1986, which continued to grow with rare publications until 1994. Between 1994 and 2007 the database was a text table online, then converted to a more readily updated website. The allergen list became the Allergen Nomenclature database (www.allergen.org), which currently includes approximately 880 proteins from a wide variety of sources. The Sub-Committee includes experts on clinical and molecular allergology. They review submissions of allergen candidates, using evidence-based criteria developed by the Sub-Committee. The review process assesses the biochemical analysis and the proof of allergenicity submitted, and aims to assign allergen names prior to publication. The Sub-Committee maintains and revises the database, and addresses continuous challenges as new "omics" technologies provide increasing data about potential new allergens. Most journals publishing information on new allergens require an official allergen name, which involves submission of confidential data to the WHO/IUIS Allergen Nomenclature Sub-Committee, sufficient to demonstrate binding of IgE from allergic subjects to the purified protein.

Ragweed and mugwort are important allergenic weeds belonging to the Asteraceae or Compositae plant family. Pollen of mugwort is one of the main causes of allergic reactions in late summer and autumn in Europe and affects about 10–14% of the patients suffering from pollinosis. Ragweed pollen represents the major source of allergenic protein in the United States, with a prevalence of about 50% in atopic individuals. In Europe, ragweed allergy is now rapidly increasing particularly in certain areas in France, Italy, Austria, Hungary, Croatia, and Bulgaria. Amb a 1 and Art v 1, the major allergens of ragweed and mugwort, respectively, are unrelated proteins. Amb a 1 is an acidic 38-kDa nonglycosylated protein. The natural protein undergoes proteolysis during purification and is cleaved into a 26-kDa alpha chain, which associates noncovalently with the beta chain of 12 kDa. The two-chain form seems to be immunologically indistinguishable from the full-length molecule. Art v 1 is a basic glycoprotein comprising two domains: an N-terminal cysteine-rich, defensin-like domain and a C-terminal proline/hydroxyproline-rich module. The proline/hydroxyproline-rich domain was recently shown to contain two types of glycosylation: (1) a large hydroxyproline-linked arabinogalactan composed of a short β1,6-galactan core substituted by a variable number (5–28) of α-arabinofuranose residues forming branched side chains with 5-, 2,5-, 3,5-, and 2,3,5-substituted arabinoses, and (2) single and adjacent β-arabinofuranoses linked to hydroxyproline. As described for other pollen, ragweed and mugwort pollen also contain the pan-allergen profilin and calcium-binding proteins, which are responsible for extensive cross-reactivity among pollen-sensitized patients.