Figure 1.

Interleukin (IL)-12 and IL-23 structure and receptors.

Notes: The IL-12 cytokine is composed of two chains, p35 and p40, which are covalently linked. p40 is shared by IL-23, which has another subunit, p19. The IL-12 receptor consists of IL-12Rβ1 and IL-12Rβ2, while the IL-23 receptor results from the association of IL-12Rβ1 and IL-23R. Ustekinumab is a human monoclonal antibody that binds to p40 shared by IL-12 and IL-23. Ustekinumab blocks the interaction of IL-12 and IL-23 with their receptor.