CD28 and psoriasis vulgaris: IDEC-114 blocks the CD28/CD80 co-stimulatory interaction which is an activation signal without affecting the CTLA4/CD80 interaction which is the deactivation signal.[27, 28] In a phase I open label study, 24 patients with severe plaque psoriasis received one single IV infusion of 0.05, 1, 5, 10, or 15 mg/kg IDEC-114.