Human and viral IL-6–induced proliferation of INA-6 cells is only partially inhibited by 10 μg/mL anti-gp130 antibodies (clone IKR3). The addition of IL-6R superantagonist Sant7 at low concentrations led to a marked increase in inhibition of hIL-6 as well as vIL-6 effects. Anti-gp130 antibodies and Sant7 were added at initiation of cultures together with IL-6.