Background:
About 2.5% of the general population show pseudoallergic
reactions to salicylates (including aspirin). Patients with aspirin-exacerbated
respiratory disease (AERD) show symptomatic improvement on low salicylate
diet1. Aspirin sensitivity is detected through oral provocation test -
contraindicated in anaphylactoid reaction. Food salicylate sensitivity is
detected through highly restrictive and lengthy ‘elimination and rechallenge
diet’ raising compliance issues. More recently, an in vitro assay, the basophil
activation test (BAT), is reported to detect pseudoallergic reactions with high
sensitivity and specificity. However, the results remain controversial.
Objective:
The aim of this study was to examine the ability of BAT to differentiate known
salicylate sensitivity from healthy controls (HC).
Design:
Peripheral blood of 10 AERD patients (2 males, 8 females), 10 HC (3 males, 7
females) was stimulated in vitro with aspirin (5, 2.5, 1.25, 0.6, 0.3, 0.15,
0.07 mg/ml). Flow cytometry was used to detect activated basophils
(IgE+/CD63+). Stimulation index (SI) and percentage activation (% act) were
used to determine basophil activation. Receiver-operator characteristics (ROC)
were determined.
Outcome:
Mean SI in AERD was similar to HC for all concentrations (p-values ranged from
0.178 (0.6mg/ml) to 0.800 (0.07 mg/ml), independent sample t-tests)). Likewise,
% act did not differ between the groups (p-values ranged from 0.869 (2.5mg/ml)
to 0.498 (5mg/ml)). No cut-off values were able to discriminate the two subject
groups (area-under-the-curve for ROC analyses <0.5 for all).
Conclusions: BAT using CD63 is unable to predict salicylate sensitivity. It may not
be an useful diagnostic test for non-IgE mediated pseudoallergic reactions.
Funding source(s): Gastroenterology department