The ability of stradomers to engage canonic FcγRs and SIGN-R1 correlates with their degree of multimerization. Recombinant mouse FcγRI, FcγRIIb, FcγRIII, FcγRIV, and SIGN-R1 were immobilized onto a CM4 (FcγRs) or CM5 (SIGN-R1) chip by amine coupling. The stradomers and Fc-modified antibodies were injected over the immobilized receptors. The SPR sensorgrams depict the association and dissociation phases of the injected proteins with the receptors. Increased affinity is indicated by higher relative RU. (A) SPR sensorgrams of stradomers binding to the canonic FcγRs and the C-type lectin SIGN-R1 are shown. (B) The 2A-2HC stradomer was separated into multimer-enriched (I) and homodimer-enriched (III) fractions. SPR sensorgrams indicate binding of IgG2a Fc, IVIG, whole 2A-2HC, fraction I, and fraction III to FcγRIIb, FcγRIII, and SIGN-R1.
Jain et al. Arthritis Research & Therapy 2012 14:R192 doi:10.1186/ar4024