TF and chronic kidney disease: Human IgG coated on microspheres was used as a positive control, and there were four negative control microspheres: (1) empty, (2) coated with only HaloTag amine ligand, (3) direct-coupled transferrin, and (4) HaloTag-coupled transferrin as autoantibodies against transferrin have not been reported in end-stage renal disease or after kidney transplantation.