IgE and monoclonal antibody reactivities to the major shrimp allergen Pen a 1 (tropomyosin) and vertebrate tropomyosins

Airborne biogenic particles in the snow of the cities of the Russian Far East as potential allergic compounds

This paper presents an analysis of airborne biogenic particles (1 mkm–1 mm) found in the snow in several cities of the Russian Far East during 2010–2013. The most common was vegetational terraneous detritus (fragments of tree and grass leaves) followed by animal hair, small insects and their fragments, microorganisms of aeroplankton, and equivocal biological garbage. Specific components were found in samples from locations close to bodies of water such as fragments of algae and mollusc shells and, marine invertebrates (needles of sea urchins and shell debris of arthropods). In most locations across the Far East (Vladivostok, Khabarovsk, Blagoveshchensk, and Ussuriysk), the content of biogenic particles collected in the winter did not exceed 10% of the total particulate matter, with the exception of Birobidzhan and the nature reserve Bastak, where it made up to 20%. Most of all biogenic compounds should be allergic: hair, fragments of tree and grass leaves, insects, and microorganisms.

Not all shellfish "allergy" is allergy!

The popularity of shellfish has been increasing worldwide, with a consequent increase in adverse reactions that can be allergic or toxic. The approximate prevalence of shellfish allergy is estimated at 0.5-2.5% of the general population, depending on degree of consumption by age and geographic regions. The manifestations of shellfish allergy vary widely, but it tends to be more severe than most other food allergens.

Tropomyosin is the major allergen and is responsible for cross-reactivity between members of the shellfish family, particularly among the crustacea. Newly described allergens and subtle differences in the structures of tropomyosin between different species of shellfish could account for the discrepancy between in vitro cross-antigenicity and clinical cross-allergenicity. The diagnosis requires a thorough medical history supported by skin testing or measurement of specific IgE level, and confirmed by appropriate oral challenge testing unless the reaction was life-threatening.

Management of shellfish allergy is basically strict elimination, which in highly allergic subjects may include avoidance of touching or smelling and the availability of self-administered epinephrine. Specific immunotherapy is not currently available and requires the development of safe and effective protocols.

Phl p 3: Structural and immunological characterization of a major allergen of timothy grass pollen

BACKGROUND

The relevant importance of individual allergens for allergic sensitization is only partially understood. More detailed information on allergen structure and how it influences immunological responses can lead to better diagnosis of disease and improved preparations for allergen-specific immunotherapy. Grass pollen contains several different allergens, and although the group 3 allergens have been classified long ago, their structure and allergenicity have been poorly investigated.

OBJECTIVE

To characterize Phl p 3 from timothy grass pollen and compare it with Phl p 2 with respect to biochemical structure and allergenicity.

METHODS

Natural Phl p 2 and Phl p 3 were separated from a pollen extract by chromatography and characterized by 2D electrophoresis and protein sequencing. The complete sequences were determined by DNA cloning and detected in natural pollen extracts by mass spectrometry. Further comparisons of the allergens were made for IgE-binding and cross-reactivity, allergenicity was determined by basophil CD203c activation and skin prick test and 3D structures were compared by molecular modelling.

RESULTS

Phl p 3 reveals molecular masses of 10.958 and 10.973 kDa and pIs of 8.9 and 9.3, respectively, Phl p 2 a molecular mass of 10.816 kDa and a pI of 4.6. The sequence identity is 58%. In spite of these differences in the primary structures, both allergens reveal similar conformational structures, resulting in similar immunological and allergological moieties.

CONCLUSIONS

The group 3 and group 2 allergens are major allergens with similar 3D structures. Although they differ considerably in their protein sequences and their pIs, they show only a slightly higher immunological reactivity for Phl p 3 on the B-cell level (conformational epitopes). But distinct differences between the sequences may influence reactivity at the T cell level.

Invertebrate Muscles: Muscle Specific Genes and Proteins

This is the first of a projected series of canonic reviews covering all invertebrate muscle literature prior to 2005 and covers muscle genes and proteins except those involved in excitation-contraction coupling (e.g., the ryanodine receptor) and those forming ligand- and voltage-dependent channels. Two themes are of primary importance. The first is the evolutionary antiquity of muscle proteins. Actin, myosin, and tropomyosin (at least, the presence of other muscle proteins in these organisms has not been examined) exist in muscle-like cells in Radiata, and almost all muscle proteins are present across Bilateria, implying that the first Bilaterian had a complete, or near-complete, complement of present-day muscle proteins. The second is the extraordinary diversity of protein isoforms and genetic mechanisms for producing them. This rich diversity suggests that studying invertebrate muscle proteins and genes can be usefully applied to resolve phylogenetic relationships and to understand protein assembly coevolution. Fully achieving these goals, however, will require examination of a much broader range of species than has been heretofore performed.

Preparation and Characterization of Monoclonal Antibody Against Abalone Allergen Tropomyosin

Muscle protein tropomyosin is a major and common allergen of mollusks. In order to develop immunoassays based on monoclonal antibody (MAb) for allergen characterization, a MAb against Japanese abalone (Haliotis discus) was prepared and characterized in the present study. In comparison with the IgE reactivities of sera from crustacean allergic individuals, the selected MAb AE9F9 showed specific reaction to the abalone allergenic tropomyosin. The MAb AE9F9 reacted to the crustaceans including lobster, crab, and shrimp, but not to the mollusks other than abalone. It was surprising that the MAb AE9F9 was also reactive to the vertebrate chicken tropomyosin and smooth muscle tropomyosin of chicken gizzard. Comparison of amino acid sequences of tropomyosins among abalone, other mollusks, crustaceans, and chicken showed that two regions (90-105 and 147-165) have a high identity among abalone, crustaceans, and chicken, but are polymorphic among mollusks. In the two regions, substitutions at residues 99-Leu, 149-Lys, and 160-Arg of abalone tropomyosin are observed only in mollusks, suggesting that these residues might be important for determining the abalone tropomyosin structure recognized by the AE9F9 antibody. Because of the distinct binding site, the MAb AE9F9 might be useful for abalone allergen detection and epitope mapping of allergen tropomyosin.

B- and T-cell epitopes of tropomyosin, the major shrimp allergen

The major crustacean allergen characterized from different species of shrimp is the muscle protein tropomyosin. Two shared epitopes corresponding to 47-63 and 150-158 of the deduced amino-acid sequence of the brown shrimp, M. ensis, were identified as IgE-binding B-cell epitopes. A 21-mer peptide spanning the amino-acid residues 261-281 was identified as a putative T-cell epitope capable of reducing ongoing tropomyosin-specific IgG and IgE responses in a mouse model. These observations suggest that peptide immunotherapy may also be effective in the treatment of food hypersensitivity.