Short-term venom immunotherapy induces desensitization of FcεRI-mediated basophil response

Background The precise immunological mechanisms for the early clinical protection of venom immunotherapy (VIT) have not yet been explained. Our aim was to evaluate whether high-affinity IgE receptor (FceRI) and the related basophil function have a role in the induction of short-term VIT protection. Methods We included 60 adults and 48 children. Basophil threshold sensitivity (CD-sens) to anti-FceRI stimulation, and FceRI gene and cell-surface expression were assessed at the beginning and just before the first maintenance dose (MD) of 100 mu g of ultra-rush VIT (day 5) and at the beginning, during buildup, and just before the first MD of 70 mu g and of 100 mu g of semi-rush VIT (weeks 12 and 5). Results We demonstrated a significant reduction in CD-sens to anti-FceRI stimulation before the first MD in both ultra-rush and semi-rush VIT in all included subjects. FceRI gene and/or cell-surface expression was decreased in 34100% of subjects, with different dynamics between VIT protocols. Conclusion We found a marked desensitization of FceRI-activated basophils after short-term VIT. This suppression, which could be highly relevant for the development of early protective mechanisms, might be also related to the changes at the level of FceRI expression.