Cul o 2 specific IgG3/5 antibodies predicted Culicoides hypersensitivity in a group imported Icelandic horses

BACKGROUND

Culicoides hypersensitivity (CH) is induced in horses by salivary allergens of Culicoides midges. In Iceland, the causal Culicoides species for CH are not present. Previous epidemiological data indicated that Icelandic horses are more susceptible to CH when they are exported from Iceland and first exposed to Culicoides at adult age. Horses born in countries where Culicoides is endemic, develop the disease less frequently. Here, we established a longitudinal allergy model to identify predictive and diagnostic serological biomarkers of CH.

RESULTS

Sixteen adult Icelandic horses from Iceland were imported to the Northeastern United States (US) during the winter and were kept in the same environment with natural Culicoides exposure for the next two years. None of the horses showed clinical allergy during the first summer of Culicoides exposure. In the second summer, 9/16 horses (56%) developed CH. Allergen specific IgE and IgG isotype responses in serum samples were analysed using nine potential Culicoides allergens in a fluorescent bead-based multiplex assay. During the first summer of Culicoides exposure, while all horses were still clinically healthy, Cul o 2 specific IgG3/5 antibodies were higher in horses that developed the allergic disease in the second summer compared to those that did not become allergic (p = 0.043). The difference in Cul o 2 specific IgG3/5 antibodies between the two groups continued to be detectable through fall (p = 0.035) and winter of the first year. During the second summer, clinical signs first appeared and Cul o 3 specific IgG3/5 isotypes were elevated in allergic horses (p = 0.041). Cul o 2 specific IgG5 (p = 0.035), and Cul o 3 specific IgG3/5 (p = 0.043) were increased in late fall of year two when clinical signs started to improve again.

CONCLUSIONS

Our results identified IgG5 and IgG3/5 antibodies against Cul o 2 and Cul o 3, respectively, as markers for CH during and shortly after the allergy season in the Northeastern US. In addition, Cul o 2 specific IgG3/5 antibodies may be valuable as a predictive biomarker of CH in horses that have been exposed to Culicoides but did not yet develop clinical signs.

Effectiveness of different proteases in reducing allergen content and IgE-binding of raw peanuts

The effectiveness of some non-specific proteases in reducing raw peanut allergenicity was investigated. Peanut kernels were treated by Alcalase, papain, Neutrase and bromelain, respectively. The residues of major peanut allergens Ara h 1, Ara h 2 and Ara h 6 were determined by sandwich ELISA and SDS-PAGE, and the allergenicities of treated peanuts were compared to that of untreated peanuts by western blot. All tested proteases were effective in reducing Ara h 1, but their effectiveness in hydrolyzing Ara h 2 and Ara h 6 varied greatly. The maximal reductions of extractable Ara h 1, Ara h 2 and Ara h 6 were 100%, 100% and 99.8%, respectively, achieved by Alcalase hydrolysis. Alcalase was more effective in overall allergenicity reduction; bromelain and Neutrase were the least effective in reducing Ara h 2 and Ara h 6, respectively. The hydrolysis of original allergens also produced some smaller peptides with strong IgE-binding.

Doses of Specific Allergens in Early Introduction Foods for Prevention of Food Allergy

BACKGROUND

Consumption of common allergenic foods, such as peanut, in early life can reduce the risk of food allergy among high-risk children and is recommended in revised clinical guidelines. Commercial early allergen introduction foods (EIF) containing single or multiple allergenic foods for feeding infants are promoted to consumers and health care providers as aids to prevent food allergy.

OBJECTIVE

To determine the concentration and doses of major food allergens in EIF.

METHODS

Extracts from 32 EIF and 4 control foods were analyzed for 17 allergens: Ara h 1, Ara h 3, Ara h 6, Bos d 5, Bos d 11, Gal d 1, Gal d 2, Ana o 3, Cor a 9, Jug r 1, Gly m 5, Ses i 1, Api g 1, Sin a 1, Cyp c 1, shrimp tropomyosin, and Tri a 19 using a validated fluorescent multiplex array. Ara h 2 was measured by enzyme-linked immunosorbent assay.

RESULTS

The EIF comprised 1-8 samples of 32 foods (n = 86). Combined peanut allergen levels of up to 26,000 μg/g were measured in peanut puffs (doses of 65-182 mg per 7 g serving). Peanut allergens were not detected in mixed food blend puffs. Major allergen levels of >10,000 μg/g were found in several milk, egg, and peanut powders, or combinations thereof, with cumulative allergen doses of 159-2946 mg in the EIF. Mixed food blend powders, puffs crackers, and fruit sauces contained much lower allergen levels, often <10 μg/g, and some had undetectable allergens. The allergen concentration in these EIF varied over a >3 log range and provided lower cumulative doses of allergen.

CONCLUSIONS

Significant variability in allergen composition, concentration, and dose per serving were observed in EIF containing the same foods. The doses of allergens consumed by potentially at-risk infants in early life were EIF dependent. Guidelines should be established to enable consumers and health care providers to make informed decisions about EIF and to improve the formulation and standardization of EIF for prevention of food allergy.

[Molecular-allergological aspects of allergen-specific immunotherapy]

Allergen-specific immunotherapy (SIT) does not achieve 100% efficacy, nor is there a reliable marker for therapy failure. However, advances in molecular allergology over the past few years have allowed a significantly improved characterization of the patients using molecular-allergological analysis methods (molecular phenotyping). Thus, major and minor allergens can be identified. In addition, the marker allergens for the severity of an allergic reaction, the pathological and therapeutic predictive marker allergens, and sensitization patterns are identified.