IgE-Api m 4 Is Useful for Identifying a Particular Phenotype of Bee Venom Allergy.

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.