Fig. 4

Functional activity of the sdab. a Inhibition of mediator release from effector cells by 026 sdab was assessed in RBL-SX38 cells providing the human FcεRI. Cells were sensitized with IgE Fc in presence of decreasing amounts of 026 sdab. Degranulation was induced by anti-IgE antibody and monitored by released β-hexosaminidase activity. Data are the mean ± standard deviation of triplicate measurements. b Removal of IgE from the surface of basophils by the 026 sdab, the inactive sdab mutant 112 and omalizumab was analyzed by surface staining of IgE using flow cytometry. Basophils of three patients with allergy to different major allergens were used. Concentration of omalizumab was identical to sdab concentrations, but doubled to 90 µmol l⁻¹ in the prolonged periods. c The capability to reduce basophil sensitivity by displacement of IgE from FcεRI was assessed by basophil activation test (BAT). Basophils were incubated with 026 sdab followed by incubation with Bet v 1. Activation of basophils was then assessed by detecting CD63⁺ basophils in flow cytometry (exemplary BAT of one donor included in panel d). Data are mean ± s.d. d The effect of the 026 sdab on basophil activation was analyzed for six birch pollen-sensitized patients. Reduction of effector cell sensitivity was evaluated by CDsens analysis. Comparison of paired samples ±sdab 026 treatment was done by using the nonparametric Wilcoxon signed-rank test. Differences were considered statistically significant at p values < 0.05. e Inhibition of IgE binding to CD23 by 026 sdab analyzed by ELIFAB. The binding of allergen:IgE complexes to surface bound CD23 was detected by anti-IgE antibodies. Complexes were formed using sera of allergic patients having highly elevated specific IgE to Api m 1, Bet v 1 and Ves v 5 (>100 kUA l⁻¹), respectively. f The displacement of preformed IgE:allergen complexes from CD23 using sera as in panel e by the sdab was analyzed by detecting remaining binding of allergen:IgE complexes after incubation with 026 sdab