Figure 2-I - uploaded by Giselda Colombo
Content may be subject to copyright.
nhibition of IgE binding to Tri a 19 (omega-5-gliadin allergen component) by gliadin extract and wheat (Triticum aestivum) extract (ALK Abellò, 1/20 W/V), as measured by ImmunoCAP. One volume of serum from patient C.P. was pre-incubated with 1.5 volumes of either saline solution or allergen extracts for prick testing at different concentrations (the latter were obtained by dilutions in saline, indicated on the x axis) and specific IgE binding was measured. Results are expressed as percent inhibition (on the y axis) versus serum diluted with saline.
Source publication
We report the case of a 62-year old man who presented a wheat-dependent, exercise-induced anaphylaxis (WDEIA). The case illustrates the usefulness of skin prick test not only with wheat extract, but also with native gliadin extract. Moreover we confirm the value of recombinant IgE dosage with rTri a 19 omega-5 gliadin in the diagnostic pathway of t...
Context in source publication
Context 1
... order to justify the discrepancy between SPT results, im- munoblotting was performed with natural wheat and gliadin extracts used for SPT (Alk Abello, Madrid, Spain - Figure 1). It demonstrates a low content of omega-5 gliadin in the whole wheat commercial extract, and also a different aller- gen content in the two extracts; moreover, to explain nega- tive SPT with whole wheat and positive with gliadin, we performed a RAST inhibition of patient serum with com- mercially whole wheat and gliadin extracts (ALK-Abellò A/S, Hørsholm, DK), which confirmed the low content of omega-5 gliadin in whole wheat extract for SPT (Figure 2). In conclusion WDEIA is a well-described clinical entity, that usually affects young adults and adolescents2. ...
Citations
... CAP-FEIA by using the recombinant omega-5 gliadin is found to have an ability to identify approximately 80% of the patients with WDEIA, resulting in similar results comparable to CAP-FEIA with the synthetic peptide [6]. The CAP-FEIA by using the recombinant omega-5 gliadin is now widely used for diagnosing wheat allergy as well as WDEIA in clinics [7,8]. In this study, we constructed a CAP-FEIA with recombinant HMW-glutenin, and evaluated its usefulness in identifying the patients with WDEIA, especially those who showed negative omega-5 gliadin-specific IgE testing. ...
Background:
Wheat-dependent exercise-induced anaphylaxis (WDEIA) is a special form of food allergy typically induced by exercise after ingestion of wheat products. We identified wheat omega-5 gliadin and high molecular weight-glutenin subunit (HMW-glutenin) as major allergens for WDEIA and clarified that simultaneous detection of serum IgE binding to synthetic epitope peptides of these allergens identifies more than 90% of WDEIA patients. However, the short synthetic peptides are not suitable for CAP-fluorescent enzyme-immunoassay (CAP-FEIA), which is widely utilized for detecting allergen-specific IgE.
Objective:
In this study, we constructed a CAP-FEIA with recombinant HMW-glutenin, and evaluated its usefulness in identifying the patients with WDEIA.
Methods:
Recombinant HMW-glutenin was expressed as histidine-tag protein in E. coli and purified by histidine-tag affinity column. Wheat, gluten, recombinant omega-5 gliadin, epitope peptide of HMW-glutenin, native and recombinant HMW-glutenin specific IgE in the sera from 48 patients with WDEIA, 16 patients with atopic dermatitis (AD) who had no immediate allergic reaction after wheat ingestion and 12 healthy controls were determined by using CAP-FEIA method.
Results:
In 16 AD patients without wheat allergy 12 of them (75%) had positive results for native HMW-glutenin test in contrast to epitope peptide of HMW-glutenin (12.5%) and recombinant HMW-glutenin test (12.5%). These results indicate the native HMW-glutenin test has low specificity. Sensitivity and specificity of the IgE test with recombinant HMW-glutenin were 16.7% and 92.9%. These are well compatible with results obtained by using epitope peptide of HMW-glutenin. However, sensitivity and specificity reached to 93.8% and 92.9%, when the test was combined to the test with recombinant omega-5 gliadin.
Conclusions and clinical relevance:
We demonstrated that recombinant HMW-glutenin is best for CAP-FEIA system in point of stability and specificity and confirmed that detection of specific IgE against recombinant HMW-glutenin is useful for diagnosis of WDEIA when combined with the CAP-FEIA (recombinant omega-5 gliadin) test.
