Fig. 6

Combination of anti-C1C2 antibodies and anti-CoRBS antibody enhanced ADCC activity. The ability of 1E5 to mediate ADCC activity was analyzed by measuring the signal through FcγRIIIa. HEK 293T cells expressing AG-257 Env were incubated with the indicated antibodies, YIR-821 and sCD4, and co-cultivated with the ADCC indicator cell line expressing FcγRIIIa. Fold change was calculated by dividing the luminescence units in the presence of Ab by those in the absence of Ab. NHG was used as a control. a 1E5-IgG1 or 1E5-IgG3 was used (10 µg/ml) alone or in combination with 4E9C (5 µg/ml), sCD4 (2 µg/ml) or CD4mc YIR-821 (20 µM). The effect of 4E9C, sCD4 and YIR-821 in the absence of test antibody is shown as a control. b Anti-C1C2 antibodies, A32 and 1E5-IgG3, and anti-CoRBS antibody, 4E9C, were used at a concentration of 10 µg/ml. The combination of anti-C1C2 antibody and anti-CoRBS antibody, as well as the combination of two anti-C1C2 antibodies, mediated stronger ADCC activity than each antibody alone. The combination of two anti-C1C2 antibodies and one anti-CoRBS antibody reached maximum enhancement at an eight-fold increase