Detection of Anisakis simplex-induced basophil activation by flow cytometry.
BACKGROUND
Laboratory diagnosis of anisakidosis is based on specific serum IgE detection. Recently, detection of allergen-induced basophil activation by flow cytometry has been proposed as a valuable tool for allergy diagnosis.


OBJECTIVE
To evaluate if detection of Anisakis-induced basophil activation by flow cytometry is a useful tool in the diagnosis of Anisakis allergy.


METHODS
Patients with Anisakis allergy (A.s.+, n = 37), patients reporting chronic urticaria or abdominal pain unrelated to fish ingestion (A.s.-, n = 51), and healthy controls (n = 12) were studied. Specific IgE to Anisakis simplex (A. simplex) was quantified with CAP-FEIA method, and basophil activation test was performed with three different concentrations of an Anisakis crude extract. Basophil gating was performed with CD123 and HLA-DR, and cellular activation was measured with CD63.


RESULTS
A.s.+ patients showed significantly higher age and total IgE levels than did the A.s.- patients. Specific IgE to A. simplex correlated with the activated basophil percentages obtained with 15 microg/mL (r = 0.80; P < 0.001), 1.5 microg/mL (r = 0.84; P < 0.001), and 0.15 microg/mL (r = 0.82; P < 0.001) of A. simplex crude extract. Nine individuals (3 in the A.s.+ group and 6 in the A.s.- group) were nonresponders to basophil stimulation with anti-IgE. Five A.s.- patients showed positive IgE values to A. simplex while the basophil activation test was negative. According to the receiver operating characteristics curves performed between A.s.+ vs. A.s.- and A.s.+ vs. healthy controls, the cutoff for a positive basophil activation test was >or=21% (specificity = 96%, sensitivity = 100%), and 16% (sensitivity and specificity of 100%) respectively. When nonresponders were included in the A.s.+ vs. A.s.- analysis, sensitivity decreased to 95%. Multivariate logistic analysis showed that the specific basophil activation was a factor independently associated with clinical symptoms of A. simplex allergy.


CONCLUSIONS
Detection of A. simplex-induced basophil activation by flow cytometry is a useful laboratory technique for the diagnosis of anisakidosis, supplementing specific IgE determinations.
Gonzalez-Muñoz
Miguel
M
Department of Immunology, H. Carlos III, Madrid, Spain. mgonzalez_munoz@hotmail.com
Luque
Rosario
R
Nauwelaers
Frans
F
Moneo
Ignacio
I
D000328:Adult; D000485:Allergens / Q000302:isolation & purification / Q000494:pharmacology; D000818:Animals; D017129:Anisakiasis / Q000175:diagnosis* / Q000276:immunology / Q000473:pathology; D017163:Anisakis / Q000737:chemistry / Q000276:immunology*; D001491:Basophils / Q000187:drug effects / Q000276:immunology* / Q000473:pathology; D005260:Female; D005434:Flow Cytometry / Q000379:methods*; D006801:Humans; D007073:Immunoglobulin E / Q000097:blood; D007814:Larva / Q000737:chemistry; D008297:Male; D008875:Middle Aged; D012372:ROC Curve; D012680:Sensitivity and Specificity
D000485:Allergens; D007073:Immunoglobulin E