Flow‐assisted quantification of in vitro activated basophils in the diagnosis of wasp venom allergy and follow‐up of wasp venom immunotherapy

Abstract

Background: Correct identification of the culprit venom is a prerequisite for specific venom immunotherapy (VIT). Despite the efficacy of VIT, issues as how to monitor treatment and when to discontinue maintenance therapy remain to be established.Methods: To evaluate diagnostic performances of the basophil activation test (BAT) in wasp venom allergy, 80 patients with a definite history of wasp venom anaphylaxis (systemic reactors) and 14 waspstung asymptomatic controls (stung controls) were enrolled. Venom-induced basophil activation was analyzed flow cytometrically by double-labeling with anti-IgE and anti-CD63. Results were compared to wasp IgE levels and results of a venom skin test (VST). To establish whether the BAT constitutes a candidate marker to monitor VIT, the BAT was repeated in 22 patients on the 5th day of a build-up course and after 6 months of maintenance VIT. Whether the BAT could contribute in the decision of discontinuing VIT was assessed in a cross-sectional analysis in 30 patients receiving treatment for 3 years.Results: Comparison between systemic reactors and stung controls revealed a sensitivity of 86.4% and specificity of 100% for venom IgE, and sensitivity of 81.8% for VST, respectively. In contrast to stung controls, patients demonstrated dose-dependent venom-induced basophil activation. The BAT attained a sensitivity of 83.8% and specificity of 100%. At the end of the build-up course, no effect of VIT on the BAT was demonstrable. When the BAT was repeated after 6 months of treatment, submaximal stimulation of the cells demonstrated a significant decreased CD63 expression (P < 0.04). Patients having VIT for 3 years also demonstrated significantly lower venom-induced CD63 expression (P < 0.001). After 3 years, 60% of the patients had a negative BAT for submaximal stimulation of the cells whereas only 17.9% of the patients had negativation of wasp IgE.Conclusions: The BAT is a reliable instrument for the diagnosis of wasp venom anaphylaxis and might constitute an instrument to monitor wasp VIT. q

Diagnostic Tests Based on Human Basophils: More Potentials and Perspectives than Pitfalls

“…The utility of BAT in hymenoptera venom hypersensitivity [34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56]has been confirmed hitherto by many more than the two studies quoted by Kleine-Tebbe et al [1] (table 2). The main benefit of BAT in that indication is that it may confirm clinical history in the absence of positive skin tests or positive allergen-specific IgE.…”

“…Considering only BAT responders (86% of all patients), BAT confirmed the final diagnosis in almost two thirds of the patients with equivocal test results and, most importantly, in all 7 patients with negative sIgE and skin test results [48]. This paper [48] has documented that BAT may also be used to monitor venom immunotherapy, although some other reports are less positive [39, 40]. When BAT are performed in whole blood, the question remains whether the decrease in reactivity observed after immunotherapy is due to competing venom-specific serum IgG antibodies, as shown for histamine release [127], or whether a true decrease in cellular reactivity also occurs in parallel.…”

“…Many of these studies have been reviewed recently [8,9,10]. Herewith, tables 1, 2, 3, 4, 5, 6, 7summarize the results of validated clinical studies performed with various allergens such as inhalant allergens [25,26,27,28,29,30,31,32,33] (table 1), hymenoptera venoms [34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56] (table 2), latex [57,58,59,60,61,62,63] (table 3), food [64,65,66,67,68,69,70,71,72,73,74,75,76,77,78,79,80] (table 4) and drugs [81,82,83,84,85,86,87,88,89,90,91,92,93,94,95,96,97,98,99,100,101,…”

Basophil Activation in Immediate Drug Hypersensitivity Reactions and Basophil Activation Test (BAT)

“…Again, the measurement that is called the area under the dose curve (AUC) depends on the combined assessment of basophil reactivity (maximal activation) and sensitivity (half of maximal activation). This is useful rather in the monitoring of allergen-specific immunotherapy (16)(17)(18).…”

Immunotherapy in allergy and cellular tests

“…22,25 Notwithstanding, very few reports exist dealing with the role of BATs in AIT, while most of them regards immunotherapy of Hymenoptera venom allergy. [26][27][28][29][30] The effect of A. mellifera venom on basophils has a nonlinear behavior, namely the Hymenoptera venom allergens used in immunotherapy (VIT) showed a biphasic or hormetic pattern on basophil IgE-mediated response, 31 then making difficult to use BAT as a simple allergy-non allergy probing test. Low doses of honey bee venom (HoBV) can diffuse into the systemic circulation and induce an activated state, while high doses elicit a primed state, but they induce IgE-FcεRIβ desensitization, as allergen/IgE cross-linking increases, a mechanism that allows many researchers to suggest that the higher the priming is, the greater the desensitization.…”