What is Ustekinumab? Ustekinumab, sold under the brand name Stelara, is a human monoclonal antibody used to treat psoriasis. It is manufactured in the Netherlands. It is directed against interleukin 12 and interleukin 23, naturally occurring proteins that regulate the immune system and immune-mediated inflammatory disorders. Stelara is also FDA approved to treat Crohn’s disease. It was found not effective for multiple sclerosis.