Peptides that specifically bind erythrocytes are described. These are provided as peptidic ligands having sequences that specifically bind, or as antibodies or fragments thereof that provide specific binding, to erythrocytes. The peptides may be prepared as molecular fusions with therapeutic agents, tolerizing antigens, or targeting peptides. Immunotolerance may be created by use of the fusions and choice of an antigen on a substance for which tolerance is desired. Fusions with targeting peptides direct the fusions to the target, for instance a tumor, where the erythrocyte-binding ligands reduce or entirely eliminate blood flow to the tumor by recruiting erythrocytes to the target.