Q:

9/11/2012
What would be appropriate to test for if a patient experienced nasal congestion and rash after eating bread and pasta?

A:

Thank you for your inquiry.

One should consider testing to every ingredient ingested during a meal preceding an allergic reaction. Testing can be done by skin test or by in vitro test or both. Skin tests can be done using commercially available extracts and fresh or cooked food the patient had during the meal. If one employs fresh or cooked food, the "prick to prick" method is usually used (see abstract copied below). This is done by pricking the food, and then using the same lancet to prick the patient's skin. If one uses fresh or cooked food, consideration should be given to performing the same test on oneself or a volunteer to rule out a non-specific irritant reaction.

So, in your case the ingredients of the meal could be tested separately, and the actual cooked food could be tested as well. In testing for the ingredients, a commercial antigen can be used, and the separate ingredients can be purchased from the grocery and tested separately as well. In vitro tests to the ingredients can also be done.

Thank you again for your inquiry and we hope this is of help to you.

J Allergy Clin Immunol. 2005 Nov;116(5):1080-6. Epub 2005 Sep 1.
In vivo assessment with prick-to-prick testing and double-blind, placebo-controlled food challenge of allergenicity of apple cultivars.
Bolhaar ST, van de Weg WE, van Ree R, Gonzalez-Mancebo E, Zuidmeer L, Bruijnzeel-Koomen CA, Fernandez-Rivas M, Jansen J, Hoffmann-Sommergruber K, Knulst AC, Gilissen LJ.
Source
Department of Dermatology, University Hospital Utrecht, The Netherlands.
Erratum in
J Allergy Clin Immunol. 2006 Jan;117(1):189.
Abstract
Background: Apple cultivars have been reported to differ in allergenicity on the basis of in vitro and skin prick tests with apple extracts.
Objectives: We sought to evaluate the efficacy of the prick-to-prick method in assessing differences in allergenicity of apple cultivars and to confirm differences by means of double-blind, placebo-controlled food challenge (DBPCFC).
Methods: Intra-assay and intracultivar variation of prick-to-prick test results were determined in 6 Dutch and 8 Spanish patients with apple allergy by using 5 apples of the cultivars Golden Delicious, Fuji, and Ecolette in duplicate. In addition, 21 cultivars were screened for allergenicity in 15 Dutch patients with birch pollen and apple allergy. Two selected cultivars (Golden Delicious and Santana) were tested with DBPCFCs. The influence of storage conditions on allergenicity was assessed in 5 cultivars.
Results: Intra-assay variation of skin prick testing was 3.9%, and intracultivar variation was 4.1%. A ranking of 21 cultivars was made on the basis of prick-to-prick tests in 9 patients. Apple cultivars were classified as of low, intermediate, and high allergenicity, with a significant difference between low and high allergenicity (P < .001). A significant difference in allergenicity determined between Golden Delicious and Santana cultivars (P < .05) was confirmed by means of DBPCFC. With 5 cultivars, controlled atmosphere (2.5% oxygen/1% carbon dioxide) was shown to reduce allergenicity (P < .001) by 15% compared with storage at 2 degrees C.
Conclusions: Prick-to-prick testing with fresh apples is a reproducible method of assessing allergenicity. Apples can be classified as of low or high allergenicity for the majority of patients. This was confirmed by using DBPCFCs. Selection of cultivars and control of storage conditions are both viable strategies for reduction of symptoms in patients with apple allergy.

Sincerely,
Phil Lieberman, M.D.

AAAAI - American Academy of Allergy Asthma & Immunology