Activation of antigen-specific T cells by artificial cell constructs having immobilized multimeric peptide–class I complexes and recombinant B7–Fc proteins

T cell activation results from the engagement of multiple receptors on T cells by their respective ligands on antigen presenting cells. Studies using artificial cell surface constructs have demonstrated that effective T cell response requires that antigen be presented on a solid surface with dimensions that approximate those of an intact cell. In this report, we describe the cloning and expression of recombinant B7-1–Fc and B7-2–Fc proteins and their incorporation onto 5-μm latex microspheres along with renatured peptide–MHC. These microspheres provide a simple and effective method for the in vitro or in vivo stimulation of antigen-specific T cells under precisely controlled antigen and costimulation conditions.