Fig. 2 | Scientific Reports

Fig. 2

From: CD38-specific nanobody-based bispecific antibody recruiters (BARs) redirect complement-dependent cytotoxicity toward multiple myeloma cells

Fig. 2

Nanobody-based CD38-specific BARs show specific and simultaneous binding to both CD38 and kappa light chain of human IgG. (a) Schematic illustration of the experimental strategy to verify binding of BARs to both CD38 and kappa light chain of human IgG. CD38-transfected HEK cells were incubated with or without 100 nM dara-scFv to block epitope E1 of CD38 (not shown). Cells were then incubated with BARs for 20 min. Human pooled serum was added as a source of unspecific IgGκ antibodies (grey). Simultaneous binding of the BARs to CD38 and IgGκ was detected using a PE-conjugated F(ab’)2 antibody (cyan) specific for human IgG. (b) FACS histograms showing simultaneous binding of CD38-BARs to both CD38 and kappa light chain of human IgG without blocking (colored histograms) and after blocking with 100 nM dara-scFv (dashed histograms). Daratumumab was used as a positive control (grey histogram). HEK cells incubated with unspecific ctrl-BAR (open histogram) were used as a negative control. (c) Median fluorescent intensities of detected hIgG (PE) as an indicator of IgG recruitment. Daratumumab served as a positive control. ctrl-BAR served as a negative control.

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