The Lights And The Shadows Of Controlled Sting Challenge With Hymenoptera

Hymenoptera venom immunotherapy (VIT) is a treatment which has been shown to be effective in the protection of individuals with systemic allergic reactions caused by Hymenoptera stings. The need for a tool which shows the degree of protection afforded by VIT and the lack of useful biomarkers, has converted the Sting Challenge Test (SCT) into the gold standard for this disorder although its use has both lights and shadows. SCT with Hymenoptera is a test consisting of causing a real sting in a patient diagnosed with an allergy to the venom of the stinging insect and who normally is undergoing treatment with specific immunotherapy. In Spain, SCT is included in the list of services offered by some hospitals and forms part of their habitual clinical practice. This review aims to analyze the strengths and weaknesses of this test and describe the standardized procedure and necessary resources, based on the experience of a group of Spanish experts and a review of the literature.

The diagnostic value of crude or boiled extracts to identify tolerant versus nontolerant lentil-sensitive children

OBJECTIVE

The aim of this study was to compare two types of lentil extracts for use in skin prick tests for the diagnosis of lentil clinical allergy.

METHODS

Thirty-six patients with a history of allergic reactions after the ingestion of lentils were skin tested with two types of lentil extracts at 0.05, 0.5, 5, and 10 mg/mL. Both extracts were extracted at 40 degrees C and afterward, one of them was boiled for 15 minutes. Thirty-three of these patients underwent oral challenges with lentils and three had a convincing recent history of lentil anaphylaxis.

RESULTS

Twenty patients had a positive oral challenge; 13 were negative. Skin prick tests performed with the boiled extract at 0.5 and 5 mg/mL were positive in 96% and 100% of patients with positive food challenge, and in 31% and 85% of those with negative food challenge, respectively; positive skin test results were similar in both groups using the crude extract. Mean wheal sizes using the boiled extract at 0.5, 5, and 10 mg/mL were significantly greater in patients with a positive oral challenge than in those with a negative one (4.9, 6.8, and 7.4 mm versus 1.9, 3.5, and 5.1 mm, respectively; P < 0.05) These mean values were not statistically different using the crude extract.

CONCLUSIONS

These data suggest that lentil extracts for the diagnosis of lentil hypersensitivity should be heated, since boiled extracts, used at a concentration of 0.5 or 5 mg/mL, best identify clinically sensitive individuals.

Hypersensitivity to members of the botanical order Fabales (legumes)

Legumes are an important source of proteins and their consumption is very frequent in the Mediterranean region and in some Asian and African countries. In some of these regions, lentils and chickpeas are one of the main food allergens. Legumes are also used as food additives due to their emulsifying properties and can be present in many manufactured foods. These hidden food allergens have the potential of causing adverse reactions in legume-sensitive subjects. The allergenic composition of various legumes has been investigated. They have been found to contain multiple allergens, a few of which have been cloned and sequenced. Legumes contain acid-resistant and thermostable allergens. There is a significant degree of cross-reactivity among legumes, the clinical relevance of which seems to be dependent on the dietary habits in different communities. In Spain, the consumption of several legumes is frequent and, therefore, clinical allergy to more than one species in children is common. Clinical manifestations include cutaneous, digestive and respiratory symptoms. Legumes can cause life-threatening reactions in sensitized individuals. Inhalation of steam, powder or flour from some legumes may cause respiratory diseases such as rhinitis, asthma and hypersensitivity pneumonitis. Soybean allergy is generally transitory, but clinical allergy to peanuts is rarely outgrown. The natural history of other legume allergies is less known and more studies are necessary to reach definite conclusions.

Specific IgE levels to Cicer arietinum (Chick pea) in tolerant and nontolerant children: evaluation of boiled and raw extracts

The chick pea, Cicer arietinum, is a legume commonly consumed in Spain and other Mediterranean countries. The sera of 29 children (mean age: 8.4 years) with a current or past history of allergic reactions after ingestion of chick pea, and positive skin tests to this legume, were used to study the allergenic composition of raw and boiled chick pea extracts. The patient population was divided into 2 groups: group 1 consisted of 19 patients with clinical sensitivity confirmed by either positive oral challenges or a convincing recent history of anaphylaxis after eating chick peas, and group 2 consisted of 10 patients with clinical sensitivity in the past, but tolerant at the time of blood extraction. Six atopic children, not allergic to legumes, were included as controls. Specific IgE to the raw and boiled extracts was measured by ELISA. The allergenic composition of both extracts was analyzed by SDS-PAGE and immunoblots. There were no significant differences between specific IgE levels to the raw and boiled extracts (p = 0.23). The mean levels in group 1 were significantly higher than in group 2 and controls (p = 0.0001). Multiple IgE binding proteins/peptides were detected in both extracts in the molecular weight range of 10-106 kD. Only nontolerant patients recognized a similar number of bands in both extracts. Chick pea extracts contain a majority of heat-stable allergens, which could be responsible for the clinical sensitivity to chick pea. Patients with a current clinical allergy to chick pea have statistically higher specific IgE levels than tolerant patients and controls.

Specific IgE determinations to crude and boiled lentil (Lens culinaris) extracts in lentil-sensitive children and controls

BACKGROUND

The aims of this study were to evaluate the allergenicity of boiled and crude lentil extracts and to compare specific IgE binding in tolerant and nontolerant lentil-allergic children.

METHODS

Thirty-eight children were studied and divided into three groups. Group I comprised 24 children with a positive open oral challenge, or a convincing history of anaphylaxis after the ingestion of lentils; group II comprised nine children with a history of allergic reactions in the past, but currently tolerant of lentils; and group III comprised five children allergic to other legumes, but always tolerant of the ingestion of lentils. Specific IgE determinations and ELISA inhibitions were performed with the crude and boiled lentil extracts. The allergenic profile of both extracts was evaluated by SDS-PAGE and immunoblot.

RESULTS

Mean specific IgE levels in group I were significantly higher than in groups II and III. The heating process caused a significant decrease in specific IgE binding. However, IgE-inhibition studies showed that the boiled lentil extract had a greater inhibitory capacity than the crude extract. Immunoblots revealed no important differences in IgE-binding patterns between the two extracts. Multiple allergens were detected in a wide range of molecular masses.

CONCLUSIONS

Boiled lentil extracts maintain strong allergenicity. Patients who have developed tolerance of lentil ingestion have lower specific IgE levels than symptomatic patients.