CD28 and psoriasis vulgaris: This agent competitively binds the B7.1 and B7.2 molecules on the surface of APCs, thereby preventing their co stimulatory interaction with CD28 on naive T cells and thus interfering with T cell activation.[26] Expression of cell surface markers like DC-LAMP, B7 and CD40 on dendritic cells and CD40 and MHC II on lesional keratinocytes was also reduced.[27] In an open label, dose-escalation, multi-center study, 43 patients with stable psoriasis vulgaris were divided into eight groups and given IV infusions of 0.5, 1, 2, 4, 8, 16, 25 and 50 mg/kg of CTLA4Ig at days 1, 2, 16, and 29.