Flow cytometric analysis of in vitro activated basophils, specific IgE and skin tests in the diagnosis of pollen-associated food allergy.
BACKGROUND
Specific immunoglobulin E (IgE) and commercially available skin prick tests have been demonstrated to be unreliable methods to diagnose pollen-associated food allergy. To evaluate the predictive value of the basophil activation test (BAT) in pollen-associated food allergy, the apple-mediated oral allergy syndrome (OAS) in patients with birch pollinosis was chosen as a representative model.


METHODS
Patients with birch pollen allergy and a history of apple-mediated OAS (OAS(+), n = 29), patients with birch allergic without OAS (OAS(-), n = 22), and healthy controls (HC, n = 10) without birch pollen allergy and OAS were included. Apple IgE was quantified by the CAP FEIA method. Skin prick tests were performed with a Jonagold apple extract. Flow cytometric analysis of basophils activated with the same Jonagold extract was based on double staining with anti-IgE/anti-CD63 monoclonal antibodies.


RESULTS
Comparison between OAS(+) subjects and HC showed sensitivities and specificities of 96% and 100% for apple IgE and 88% and 100% for the apple skin prick test, respectively. For the BAT, sensitivity and specificity were 100%. In contrast, when nonresponders on the BAT were considered, sensitivity decreased to 90%. In a separate analysis between OAS(+) and OAS(-) subjects, specificities decreased to 30% for apple IgE and to 80% for the apple skin test, respectively. The BAT reached a sensitivity of 88% and a specificity of 75%.


CONCLUSIONS
Flow cytometry-assisted quantification of in vitro basophil activation seems to be a reliable instrument in the diagnosis of this model of pollen-associated food allergy. In addition, this study reemphasizes that the specificity of diagnostic allergy tests decreases considerably when, apart from HC, control individuals with cross-reactive antibodies are included.
Ebo
Didier G
DG
Department of Immunology, Allergology, and Rheumatology, University of Antwerp, Antwerp, Belgium.
Hagendorens
Margo M
MM
Bridts
Chris H
CH
Schuerwegh
Annemie J
AJ
De Clerck
Luc S
LS
Stevens
Wim J
WJ
D000293:Adolescent; D000328:Adult; D000368:Aged; D015703:Antigens, CD / Q000378:metabolism; D001491:Basophils / Q000276:immunology* / Q000378:metabolism; D029662:Betula / Q000276:immunology; D005260:Female; D005434:Flow Cytometry / Q000379:methods*; D005512:Food Hypersensitivity / Q000175:diagnosis* / Q000276:immunology; D006801:Humans; D007073:Immunoglobulin E / Q000097:blood*; D008297:Male; D027845:Malus / Q000276:immunology; D008875:Middle Aged; D010980:Platelet Membrane Glycoproteins / Q000378:metabolism; D011058:Pollen / Q000276:immunology*; D012372:ROC Curve; D012680:Sensitivity and Specificity; D012882:Skin Tests; D060149:Tetraspanin 30; D015854:Up-Regulation / Q000276:immunology
D015703:Antigens, CD; C554586:CD63 protein, human; D010980:Platelet Membrane Glycoproteins; D060149:Tetraspanin 30; D007073:Immunoglobulin E