Detection of changes in surface protein expression in allergen-specific memory B cells as biomarker for successful immunotherapy. (A) Schematic representation of allergen-specific memory B cells (Bmem). Following AIT, either sublingual (SLIT) for ryegrass pollen or subcutaneous (SCIT) for bee venom, a large fractions of allergen-specific Bmem expressed surface CD23, CD29, IL4Rα and/or IgG4. (B) Example dot plots of Bmem stained with fluorochrome-coupled allergen tetramers for bee venom (Api m 1) or ryegrass pollen (Lol p 1). 1 By using two tetramers of the same allergen coupled with distinct fluorochromes, the allergen-specific Bmem population can be distinguished through 'double discrimination', ensuring that fluorochrome-specific Bmem are excluded. (C) Evaluation of surface markers expression on allergen-specific Bmem showing increased frequencies of cells expressing CD29 and IL4Rα. 1