Usefulness of manufactured tomato extracts in the diagnosis of tomato sensitization: Comparison with the prick-prick method

<p>Abstract</p> <p>Background</p> <p>Commercial available skin prick test with fruits can be negative in sensitized or allergic patients due to a reduction in biological activity during the manufacturing process. Prick-prick tests with fresh foods are often preferred, but they are a non-standardized procedure. The usefulness of freeze-dried extracts of Canary Islands tomatoes, comparing the wheal sizes induced by prick test with the prick-prick method in the diagnosis of tomato sensitization has been analyzed.</p> <p>The objective of the study was to assess the potential diagnostic of freeze-dried extracts of Canary Islands tomatoes, comparing the wheal sizes induced by prick test with the prick-prick method.</p> <p>Methods</p> <p>Two groups of patients were analyzed: Group I: 26 individuals reporting clinical symptoms induced by tomato contact or ingestion. Group II: 71 control individuals with no symptoms induced by tomato: 12 of them were previously skin prick test positive to a tomato extract, 39 were atopic and 20 were non-atopic. All individuals underwent prick-prick with fresh ripe peel Canary tomatoes and skin prick tested with freeze-dried peel and pulp extracts obtained from peel and pulp of Canary tomatoes at 10 mg/ml. Wheal sizes and prick test positivity (≥ 7 mm²) were compared between groups.</p> <p>Results</p> <p>In group I, 21 (81%) out of 26 patients were prick-prick positive. Twenty patients (77%) had positive skin prick test to peel extracts and 12 (46%) to pulp extracts. Prick-prick induced a mean wheal size of 43.81 ± 40.19 mm²compared with 44.25 ± 36.68 mm²induced by the peel extract (Not significant), and 17.79 ± 9.39 mm²induced by the pulp extract (p < 0.01).</p> <p>In group II, 13 (18%) out of 71 control patients were prick-prick positive. Twelve patients (all of them previously positive to peel extract) had positive skin prick test to peel and 3 to pulp. Prick-prick induced a mean wheal size of 28.88 ± 13.12 mm²compared with 33.17 ± 17.55 mm²induced by peel extract (Not significant), and 13.33 ± 4.80 mm²induced by pulp extract (p < 0.05 with peel extract and prick-prick).</p> <p>Conclusion</p> <p>Canary peel tomato extract seems to be as efficient as prick-prick tests with ripe tomatoes to diagnose patients sensitized to tomato. The wheal sizes induced by prick-prick and peel extracts were very similar and showed a high correlation coefficient.</p

Allergenicity of casein containing chalk in milk allergic schoolchildren

Background: Nondietary exposure to milk proteins may be a risk for children who do not outgrow milk allergy by school age. Objective: To study the allergenicity of casein containing chalk. Methods: A 6-year-old, milk allergic child developed asthma and rhinoconjunctivitis while in school. The suspected cause was dust-free chalk containing casein. To study the relationship of dust-free chalk containing casein with asthma and rhinoconjunctivitis, 13 additional milk allergic patients were studied: 3 school-aged children, 8 preschool-aged infants, and 2 children with outgrown milk allergy. Skin tests and/or specific IgE with chalk and casein were performed. A chalk use test was performed in older children. Milk allergens contained in chalk were characterized by sodium dodecyl sulfate–polyacrylamide gel electrophoresis, immunoblot, and IgE inhibition experiments. Results: All school-aged, milk allergic children were exposed to chalk and reported symptoms attributed to chalk exposure. The skin test result to chalk was positive in 5 of 12 cases, and the specific IgE test result was positive in all 12 study participants in which it was performed. Casein strongly inhibited the binding of IgE to chalk. Chalk sodium dodecyl sulfate–polyacrylamide gel electrophoresis showed proteins with molecular weight similar to caseins. Immunoblot demonstrated strong binding of IgE to chalk in a blurred pattern and a band at 30 kDa, inhibited by casein. The chalk challenge test result was positive in 2 school-age children who had a positive skin test result to chalk. Their symptoms improved after avoidance of chalk in the school. In 2 other cases in which the challenge test result was negative, chalk was reintroduced without problems. Conclusion: Inhalation of chalk dust containing casein can induce asthma symptoms in milk allergic patients. Hidden and nondietary sources of exposure should always be considered in food allergic patients