Figure 3: Binding strength of antibodies to PF4/H complexes measured by SMFS.
From: Anti-platelet factor 4/polyanion antibodies mediate a new mechanism of autoimmunity
Experimental setup: (a) via PEG linkers, a single antibody is attached covalently on an AFM-tip, while the PF4/H complex is immobilized on the substrate. (b) The antibody interacts with the PF4/H complex when the tip approaches the substrate. (c) When the tip moves away from the substrate, the rupture force of the antibody from the complex is recorded. (d) Typical force–distance curve showing the rupture force (F) between group-3 ABS and the PF4/H complexes. (e) The average rupture force and the corresponding s.e. were determined by a Gaussian fit (solid curves) shown for one representative experiment for human control IgG (black), KKO (grey), group-1 ABS (dark cyan), group-2 ABS (blue) and group-3 ABS (red). (f) Average rupture forces and s.d. obtained from different cantilevers for KKO (grey; n=18), group-1 ABS (dark cyan; n=43), group-2 ABS (blue; n=54) and group-3 ABS (red; n=51). Group-2 and group-3 showed higher rupture forces than group-1 ABS and KKO. Rupture force between KKO and group-1 ABS did not differ significantly (P=0.877), while group-2 differ significantly from group-1 (P<0.001) and group-3 differ significantly from group-2 ABS (P=0.006).
