Diagnosis of Apis dorsata venom allergy: use of recombinant allergens of Apis mellifera and a passive basophil activation test

Abstract

AbstractBackgroundAllergy toApis dorsata(Giant Asian Honeybee) venom is the commonest insect allergy in Sri Lanka and South East Asia. However, laboratory diagnosis is difficult as the pure venom and diagnostic reagents are not commercially available.ObjectiveThis study assessed the use of four recombinant allergens ofA. melliferavenom and the passive basophil activation test in the diagnosis ofA. dorsatavenom anaphylaxis.MethodsSerum IgE levels to four recombinant allergens ofA. mellifera, rApi m 1, 2, 5 and 10 were assessed and compared with serum IgE to the crude venom ofA. melliferaorV. vulgarisby Phadia ImmunoCAP, in patients who developed anaphylaxis toA. dorsatastings. Basophil activation in response to venom ofA. dorsataorV. affiniswas assessed using a passive basophil activation test. Association of the severity of the reaction with basophil activation was compared.ResultsrApi m 1 and 10 combinedly had significant correlation (r = 0.722; p < 0.001) with the crude venom ofA. mellifera(Western honeybee) and a higher positivity rate of 90% (27/30). Whereas, IgE reactivity to rApi m 2 or 5 had significant correlation (p = 0.02 and p = 0.005 respectively) withV. vulgariscrude venom. All 30 (100%) were positive toA. dorsatavenom in passive BAT; 70% (21/30) had over 80% activation, 96.7% (29/30) had over 60% activation and 100% had over 50% activation. Percentage activation of basophils in patients who had mild or moderate reactions (n = 20) was significantly low (p = 0.02) from that of patients who had severe reactions (n = 10).ConclusionsrApi m 1 and 10 when combined was sensitive for the diagnosis ofA. dorsataallergy. This combination had the lowest cross-reactivity rate withVespula vulgaris. The passive BAT is highly sensitive inA. dorsataallergy. The basophil reactivity was significantly higher in severe anaphylaxis compared to mild/moderate anaphylaxis. This finding should be further explored in further studies.