Siltuximab The Siltuximab antibody is a chimeric mouse/human therapeutic antibody obtained from mouse hybridoma. It is one of several IgG1 antibodies known to bind the human interleukin 6 (IL-6) molecule, a soluble glycoprotein with a key role in pro-inflammatory responses. IL-6 is one of the main proinflammatory cytokines overexpressed in multiple pathologies (e.g. viral infections, rheumatoid arthritis, MCD, etc.).