Immunological differences between insect venom-allergic patients with and without immunotherapy and asymptomatically sensitized subjects.

BACKGROUND: Currently available tests are unable to distinguish between asymptomatic sensitization and clinically relevant Hymenoptera venom allergy. A reliable serological marker to monitor venom immunotherapy (VIT) does also not exist. Our aim was to find reliable serological markers to predict tolerance to bee and vespid stings. METHODS: We included 77 asymptomatically sensitized subjects, 85 allergic patients with acute systemic sting reactions, and 61 allergic patients currently treated with VIT. Levels of sIgE and sIgG4 to bee and vespid venom, rApi m 1, and rVes v 5 were measured immediately after allergic sting reactions or before sting challenges and 4 weeks later. All sting challenges were tolerated. The inhibitory activity was determined using BAT inhibition and ELIFAB assay. RESULTS: Median sIgG4 levels were 96-fold higher in VIT patients (P < .001) while sIgE/sIgG4 ratios were consistently lower (P < .001). The ELIFAB assay was paralleled by low sIgE/sIgG4 ratios in VIT patients, showing markedly higher allergen-blocking capacity (P < .001). An almost complete inhibition of the basophil response was seen in all patients treated with vespid venom, but not in those treated with bee venom. Four weeks after the sting, sIgE and sIgG4 levels were increased in allergic and asymptomatically sensitized patients, but not in VIT patients. CONCLUSION: Immunological responses after stings varied in bee and vespid venom-allergic patients. In patients under VIT, sIgE and sIgG4 remained completely stable after sting challenges. Monitoring VIT efficacy was only possible in vespid venom allergy, and the sIgG4 threshold for rVes v 5 had the highest sensitivity to confirm tolerance. The BAT inhibition test was the most reliable tool to confirm tolerance on an individual basis.

Questionable diagnostic benefit of the commercially available panel of bee venom components.

For many years, only the major allergen rApi m 1 has been available on the ImmunoCAP system for routine diagnosis of bee venom (BV) allergy. Now, there are five components available, and we aimed to detect the sensitivity and specificity of rApi m 1, 2, 3, 5, and 10 in BV-allergic patients. We further evaluated the sensitivity of rApi m 1 and 2 of an alternative platform and investigated possible differences in the sensitization profile between monosensitization and clinically relevant double sensitization. Analysis of the whole panel of BV allergens of the CAP system still resulted in a lower sensitivity than analysis of the combination of rApi m 1 and 2 of the Immulite (71.6% vs 85.8%). Sensitization rate of rApi m 5 was more than doubled in double-sensitized patients, while there was no difference for rApi m 2. The benefit of the commercially available panel of BV components is questionable, due to the insufficient sensitivity and still unavailable important cross-reacting allergens.

Hymenoptera stings in the head region induce impressive, but not severe sting reactions.

Stings in the head region are considered to be a risk factor for severe systemic reactions to hymenoptera stings. We supposed that stings in skin areas, which are well supplied with blood, lead to more severe reactions and tested our hypothesis in 847 patients with confirmed hymenoptera venom allergy. However, symptom severity was independent from sting site: only 16.3% of patients with severe reactions were stung on the head (P = 0.017). But we confirmed age > 40 years (P < 0.001) as well as elevated basal tryptase levels (P = 0.001) as risk factors. Taking antihypertensive drugs seemed to have an influence: 41.7% of patients taking antihypertensive drugs experienced a severe reaction compared to 29.5% of patients, not taking such drugs (P = 0.019). However, considering patients' age in regression analysis, taking antihypertensive drugs had no effect on symptom severity (P = 0.342). Importantly, in most patients with severe reactions, cutaneous signs were absent (P < 0.001).