Figure 6.

FcγR binding and ADE risk of Fc-engineered antibodies. Anti-CD154 antibodies with the Fc variants, hIgG₁, LALA, LALA/KAES, or LALA/KAES/ACT5, were prepared and immune complexes (ICs) were formed by adding CD154 to allow strong avidity binding to FcγRs. The binding of the antigen-free antibodies (blue) and ICs (red) of each antibody to human FcγRIIa-H131 (A) and human FcγRIIa-R131 (B) was measured by SPR analysis. In addition, the potential ADE risk of the anti-DENV antibodies on K562 cells against DENV-2 in non-heat-inactivated serum (C) or in heat-inactivated serum (D) was assessed by quantifying the virus in the supernatant of K562 cells. Enhancement observed with the human IgG₁ (blue) was abrogated with the LALA/KAES/ACT5 variant (orange). The variable region of the anti-DENV antibodies was an engineered variant termed 3Cam2, which has improved affinity toward E-proteins of the four DENV serotypes.