Introducing chemists to food allergy

Adverse reactions to food may be toxic or non toxic, depending on the susceptibility to a certain food; non toxic reactions that involve immune mechanisms are termed allergy if they are IgE-mediated. If no immunological mechanism is responsible, it is termed intolerance. The following disorders are considered a consequence of food allergy: gastrointestinal reactions (oral allergy syndrome, vomiting, diarrhea, protein-induced enterocolitic syndrome, eosinophilic gastroenteritis); respiratory reactions (rhinitis, asthma, laryngeal edema); cutaneous reactions (urticaria-angioedema, atopic dermatitis); anaphylaxis. There is much recent evidence to consider celiac disease an immunological disorder. Food allergy diagnosis is based on history, SPT, specific IgE, food challenges. DBPCFC is fundamental for diagnosing true food allergy; patients who have had anaphylaxis to food must not undergo DBPCFC. Rapidly progressive respiratory reactions and anaphylactic shock are life-threatening reactions that can be caused by food allergy. The doses of food inducing anaphylaxis can be very low, therefore commercial cross-contamination with an unsuspected food during food processing can be risky for the food allergic patient. The prevention of severe anaphylactic food reactions may lie in interdisciplinary collaboration among allergologists, chemists, food technologists, and experts in food industry research

IgE-mediated allergy from vegetable allergens

Allergy to fresh fruits and vegetables is IgE-mediated. Its main clinical features are local, such as oral pruritus and swelling of lips and tongue but systemic symptoms such as urticaria, asthma, or anaphylactic shock may occur. Clinical associations with allergic rhinitis due to cross-reactive antigens of pollens and foods are frequent

Hypersensitivity to mugwort (Artemisia vulgaris) in patients with peach allergy is due to a common lipid transfer protein allergen and is often without clinical expression

Background: The observation of mugwrort-specific IgE antibodies in patients with peach allergy suggests that mugwort sensitization might play a role in sensitization to peach. Objective: We sought to study the clinical manifestations of mugwort hypersensitivity in patients with peach allergy, identify the common allergens, and evaluate their IgE cross-reactivity. Methods: Patients with oral allergy syndrome for peach and specific IgE antibodies to mugwort were investigated for respiratory symptoms during the mugwort season. Peach and mugwort allergens were identified by means of SDS-PAGE and IgE immunoblotting. Immunoblotting inhibition experiments were done to study cross-reactivity between peach and mugwort and other pollens. Results: Seventeen patients were studied, 10 with no seasonal respiratory symptoms and 7 with clear late summer respiratory symptoms. In IgE immunoblotting the 10 asymptomatic patients reacted only to a 9-kd allergen of both mugwort and peach, whereas the 7 patients with pollinosis reacted to other allergens. Ten patients with mugwort allergy, no history of allergy to peach, and negative results for peach-specific IgE antibodies were also studied. The mugwort 9-kd protein was identified as a lipid transfer protein (LTP) homologous to peach LTP. Immunoblotting inhibition showed that IgE binding to the peach 9-kd band was totally inhibited by 4 mug of peach LTP but only by 400 mug of mugwort LTP, whereas 4 mug of both mugwort and peach LTP totally inhibited the mugwort immunoblotting. The results were similar with other pollens. Conclusions: Patients sensitized only to the 9-kd LTP of mugwort do not present hay fever symptoms, and this sensitization is a consequence of the peach sensitization

A double-blind placebo-controlled study of immunotherapy with an alginate-conjugated extract of Parietaria judaica in patients with parietaria hay fever

A double-blind, placebo-controlled study was conducted to evaluate the efficacy and safety of immunotherapy (IT) with a partially purified alginate-conjugated extract of Parietaria judaica (Conjuvac(R) Parietaria, Dome/Hollister-Stier) in patients suffering from rhinoconjunctivitis caused by Parietaria pollen. Eighteen patients (10 women, 8 men, mean age 35 years) received active treatment and 17 (10 women, 7 men, mean age 42.5 years) received placebo. Actively treated patients had significantly lower nasal symptom/medication scores (running nose P = 0.0087 and sneezing P = 0.048) during the Parietaria pollen season. Significant decreases in specific skin (P< 0.01), nasal (P< 0.05), and conjunctival (P< 0.01) reactivity to the Parietaria extract and significant increases of specific IgG (P< 0.001), IgG1 (P< 0.001), and IgG4 (P< 0.001) in actively treated patients, but not in placebo, were found. IT was well tolerated, the active extract inducing five mild systemic reactions (four rhinitis and one urticaria) and placebo two (rhinitis). A significant correlation was found between low skin reactivity and high specific IgG (P = 0.0002) and IgG4 (P = 0.036). These findings indicate that IT with a partially purified P. judaica extract is an effective and safe treatment for Parietaria pollen allergy. The correlation between low immediate skin reactivity and high specific IgG and IgG4 suggests that, at least in the studied cutaneous model, these antibodies may exert a blocking effect

The major allergen of peach (Prunus persica) is a lipid transfer protein.

Background: Allergy to fresh fruits and vegetables is mostly observed in subjects with pollinosis, especially from birch, because of cross-reacting allergens in vegetable foods and pollens. However, allergic reactions to fruits, specifically Rosaceae fruits, have been reported in subjects without pollinosis. Objective: This study evaluated the pattern of IgE reactivity, identifying the allergen responsible in 2 groups of patients with oral allergy syndrome to peach with or without birch pollinosis. Methods: The allergenic components of peach were detected by SDS-PAGE and immunoblotting. The major peach allergen was purified by HPLC with a cation-exchange column followed by gel filtration chromatography. Its IgE-binding capacity and its homology with the protein of the crude extract were demonstrated by immunoblotting inhibition techniques. To better characterize this allergen, periodic acid-Schiff stain and isoelectrofocusing were used. The amino acid sequencing was done with a gas-phase sequencer. Results: SDS-PAGE and immunoblotting of the 15 patients allergic to peach, 8 without and 7 with birch pollinosis, showed that they all recognized a protein with a molecular weight of 9 kd. This was the only allergen recognized by patients not sensitized to pollen, whereas the birch pollen\u2013sensitive patients had IgE binding to other allergenic proteins at higher molecular weights. The purified 9-kd protein retained its IgE-binding capacity, was negative to periodic acid-Schiff stain, and had an isoelectric point value of greater than 9. A search in the Swiss Prot Bank showed this was a lipid transfer protein, belonging to a group of molecules involved in the defensive system of plants. Conclusions: The major allergen of peach is a 9-kd protein belonging to the group of lipid transfer proteins. This is the only allergen recognized by patients allergic to peach but not sensitized to birch pollen