Selected 2S albumin-specific mAbs can induce degranulation
As IgE B-cell memory is potentially stored in IgG1+ memory B-cells and to a lesser extent in B-cells belonging to another isotype, the functionality of mAbs originated from non-IgE 2S albumin-binding B-cells was examined19-21. To determine mAb functionality, stripped human basophils were loaded with mixtures of randomly selected mAbs (IgE) and subsequently stimulated with Ara h2 and 6 (Figure 2C and Supplementary, Figure S4). Stimulated basophils showed individual CD63 upregulation upon stimulation when loaded with mixtures containing the mAb Pt-6-2 (Mix-1, 2, 3 and 6). Such responses were already achieved at low concentrations (5 ng/ml Ara h2/6). Moreover, the overall CD63 upregulation induced by Mix 3 and 6 was even higher than the CD63 upregulation induced by the anti-IgE control at all allergen concentrations, pointing to an additive effect by using mAb Pt-6-2 (Mix-1) in combination with additional mAbs. The functionality of mAb Pt-6-2 and the observed additive effect confirm the selection of specific and functional B-cells.