Background and Objective: Different clinical behaviors have been identified in patients allergic to bee venom. Compound-resolved diagnosis could be an appropriate tool for investigating these differences. The aims of this study were to analyze whether specific IgE to Api m 4 (sIgE-Api m 4) can identify a particular kind of bee venom allergy and to describe response to bee venom immunotherapy (bVIT).

Methods: Prospective study of 31 patients allergic to bee venom who were assigned to phenotype group A (sIgE-Api m 4 <0.98 kU/L), treated with native aqueous (NA) extract, or phenotype group B (sIgE-Api m 4 ≥0.98 kU/L), treated with purified aqueous (PA) extract. Sex, age, cardiovascular risk, severity of preceding sting reaction, exposure to beekeeping, and immunological data (intradermal test, sIgE/sIgG4-Apis-nApi m 1, and sIgE-rApi m 2-Api m 4 were analyzed. Systemic reactions (SRs) during bVIT build-up were analyzed. Immunological and sting challenge outcomes were evaluated in each group after 1 and 2 years of bVIT.

Results: Phenotype B patients had more severe reactions (P=.049) and higher skin sensitivity (P=.011), baseline sIgE-Apis (P=.0004), sIgE-nApi m 1 (P=.0004), and sIgG4-Apis (P=.027) than phenotype A patients. Furthermore, 41% of patients in group B experienced SRs during the build-up phase with NA; the sting challenge success rate in this group was 82%. There were no significant reductions in serial intradermal test results, but an intense reduction in sIgE-nApi m 1 (P=.013) and sIgE-Api m 4 (P=.004) was observed after the first year of bVIT.

Conclusion: Use of IgE-Api m 4 as the only discrimination criterion demonstrated differences in bee venom allergy. Further investigation with larger populations is necessary.

Key words: Bee venom allergens, Bee venom immunotherapy, Component-resolved diagnosis, Sting challenge, Systemic reaction.