Rapid Change in FcεRI Occupancy on Basophils After Venom Immunotherapy Induction

Area of Science:

• Immunology
• Allergy Research
• Cellular Mechanisms

Background:

• Hymenoptera venom allergy (HVA) management often involves venom immunotherapy (VIT).
• Mechanisms of early tolerance induction during VIT at the cellular level remain poorly understood.
• Investigating rapid cellular changes is crucial for understanding VIT efficacy.

Purpose of the Study:

• To investigate the immediate cellular-level changes occurring within the first hours of VIT induction in HVA patients.
• To assess alterations in basophil high-affinity IgE receptor (FcεRI) expression and activation.
• To correlate these cellular changes with serum markers and basophil activation tests (BATs).

Main Methods:

• Measurement of total and unoccupied FcεRI on basophils before and after the first day of VIT.
• Quantification of serum tryptase and soluble FcεRI (sFcεRI) levels.
• Performance of basophil activation tests (BATs) to assess basophil sensitivity (EC50).

Main Results:

• A significant increase in unoccupied FcεRI on basophils was observed post-VIT induction, particularly in patients with high total IgE.
• No significant changes were noted in total FcεRI density, serum tryptase, or sFcεRI levels.
• BATs showed heterogeneous results, with most patients exhibiting unchanged or increased basophil sensitivity.

Conclusions:

• Early VIT induction induces subthreshold basophil activation, evidenced by increased unoccupied FcεRI, suggesting receptor internalization and recycling.
• The observed rapid receptor modulation occurs independently of significant changes in serum tryptase or sFcεRI.
• Further research is needed to clarify the clinical significance of unchanged or increased basophil sensitivity in early VIT.