Objective: Venom immunotherapy (VIT) is recommended as the first-line therapy in patients with Hymenoptera venom allergy. The frequency of adverse reactions and side effects during VIT has been reported at variable rates. Our study aims to investigate the factors affecting of primary bee sting allergic reactions, re-sting allergic reactions in the course of VIT, and allergic reactions due to VIT injections.

Material and Method: The patients, who received VIT in the Ege University Medical Faculty, Department of Internal Medicine, Division of Allergy and Clinic Immunology, allergy outpatient clinic between January 2014 and September 2019, were reviewed retrospectively. Demographic data, basal serum tryptase (BST) levels, the severity of primary sting reactions according to Mueller classification, use of antihypertensive drugs, skin prick test and venom-specific IgE results, presence of allergic reactions after VIT injections and re-sting reactions in the field were investigated.

Results: Sixty-seven (n=67, 23 F/44 M) patients with a median age (min-max) of 46 (19-66) were included. 43% (n=29) were receving VIT with Apis mellifera venom, 48% (n=32) Vespula vulgaris, and 9% (n=6) of them were receiving VIT with both venom types. In skin tests, positivity was detected with a single venom in 69% of patients, positivity was detected with double venom in 30%, and positivity with all 3 venom allergen extracts (Apis, Vespula, and Polistes) in 1% of patients. The frequency of systemic reaction during VIT was higher in patients who were sensitive to two bees in skin tests (Apis + Vespula); the frequency of large local reactions with VIT was found to be high in patients who are sensitive to three bees (Apis + Vespula + Polistes) (p=0.005). The frequency of local bee-sting reactions was higher in patients using antihypertensive drugs (n=6) and the frequency of systemic reactions was higher in patients who did not use the antihypertensive drugs (p=0.001). Primary hypersensitivity reactions (HSR) of the patients were graded according to Mueller classification, and groups were compared according to the mean BST levels. While no significant difference was found between grade 2 HSR (BST: 5.21 ng/ml) and grade 3 HSR (BST: 5.10 ng/ml); the mean BST value (10 ng/ml) in patients with grade 4 reaction were significantly higher than the other groups (p=0.023). The patients were classified according to the type of VIT and the groups were compared according to the mean BST levels. The BST level of the patients sensitive to both bee types (Apis+Vespula) (14.92 ng/ml) was compared to the BST level of the Vespula-only sensitive patients (6.57 ng/ml) and the BST level of the Apis-only sensitive patients only (6.09 ng/ml) ([p=0.020 vs 0.016)]. When the patients were evaluated according to the type of bee to which they were sensitive, the primary reaction, the re-sting reaction, and the reaction during VIT were compared and no significant results were found.

Conclusion: The use of antihypertensive does not increase the frequency of life-threatening reactions with bee stings both during VIT and re-sting reactions in the field. During VIT; There is an increase in all reactions, especially in the dose escalation phase. Systemic reaction development during VIT is significantly higher in those with sensitivity to both venoms in skin tests. The BST value of patients who are susceptible to both venoms and whose primary reaction is Mueller class 4 should be investigated. Bee species and venom specific IgE levels do not affect the frequency of allergic reactions.

Venom allergy Venom immunotherapy Hypersensitivity reaction Risk factors