Abstract: Disclosed are methods for modulating an immune response including a method for inhibiting the interaction between a B7 polypeptide and a PD-1 ligand, the method comprising contacting an immune cell bearing a PD-1 ligand, or an immune cell bearing a B7 polypeptide, with an agent that inhibits the interaction between the PD-1 ligand and the B7 polypeptide. Such agents may be an anti-PD-1 ligand antibody or a small molecule. Also disclosed is a method for modulating an immune response comprising contacting an immune cell bearing the PD-1 ligand, or an immune cell bearing the PD-1 polypeptide, with an agent that inhibits interactions between the PD-1 ligand and the PD-1 polypeptide, without inhibiting interactions between the PD-1 ligand and a B7 polypeptide, to thereby modulate an immune response. The agent may be an anti-PD-1 ligand antibody or a small molecule.

Abstract: Disclosed are methods for identifying an agent that modulates an immune response. One such method comprises screening for agents which inhibit the interaction between a PD-1 ligand and a PD-1 polypeptide, and determining whether the agents inhibit the interaction between a PD-1 ligand and a B7 polypeptide, to identify an agent that inhibits PD-1 ligand and PD-1 polypeptide interaction, while not inhibiting the interaction between a PD-1 ligand and a B7 polypeptide, as an agent that modulates an immune response. Another such method comprises screening for agents which inhibit the interaction between a PD-1 ligand and a B7 polypeptide, and determining whether the agents inhibit the interaction between a PD-1 ligand and a PD-1 polypeptide, to identify an agent that inhibits the PD-1 ligand and B7 polypeptide interaction, which does not inhibit the interaction between a PD-1 ligand and a PD-1 polypeptide, as an agent that modulates the immune response.

Abstract: Disclosed are methods for identifying an agent that modulates an immune response. One such method comprises screening for agents which inhibit the interaction between a PD-1 ligand and a PD-1 polypeptide, and determining whether the agents inhibit the interaction between a PD-1 ligand and a B7 polypeptide, to identify an agent that inhibits PD-1 ligand and PD-1 polypeptide interaction, while not inhibiting the interaction between a PD-1 ligand and a B7 polypeptide, as an agent that modulates an immune response. Another such method comprises screening for agents which inhibit the interaction between a PD-1 ligand and a B7 polypeptide, and determining whether the agents inhibit the interaction between a PD-1 ligand and a PD-1 polypeptide, to identify an agent that inhibits the PD-1 ligand and B7 polypeptide interaction, which does not inhibit the interaction between a PD-1 ligand and a PD-1 polypeptide, as an agent that modulates the immune response.