The disclosure provides antibody immune cell inhibitor fusion proteins comprising four polypeptide chains that form two antigen binding sites and at least two immune cell receptor binding sites that inhibit or diminish activation of an immune effector cell when bound to a target antigen. The disclosure also provides antibody immune cell inhibitor fusion proteins comprising two polypeptide chains that form one antigen binding site and at least one immune cell receptor binding site that inhibit or diminish activation of an immune effector cell when bound to a target antigen. The disclosure further provides pharmaceutical compositions and kits that comprise such antibody immune cell inhibitor fusion proteins, and methods of treatment using such proteins.