Fig. 8: A schematic representation of two scenarios of platelet activation by immune complexes built upon SC/KKO association.

Left: KKO2·(PF4)3·heparin, the largest SC/KKO complexes produced in solution, bind to the FcγRIIa receptors on the platelet surface, which leads to the pairing of the ITAM segments and enables their activation. Right: the receptor-bound KKO2·(PF4)3·heparin complexes are cross-linked by SCs via the “vacant” Fab arms of the antibody molecules, giving rise to large FcγRIIa clusters on the platelet surface and close localization of multiple ITAM segments.