Figure 6. Proposed model for CTLA4Ig.
Binding of CTLA4Ig to CD80/CD86 expressed on an antigen presenting cell can prevent naïve T cell activation by preventing CD28 mediated costimulation (left panel). In addition, CTLA4Ig can suppress the proliferation of activated effector T cells (Teff) through a TGFβ and Treg dependent mechanism that is independent of CD28-costimulation (right panel). This pathway requires and is synergistic with macrophage derived NO.