Urinary autoantibodies against intrinsic factor in pernicious anaemia patients

In radioimmunoassay seven concentrated urines of penicious anaemia (PA) patients were positive for intrinsic factor (IF). Four were studied by gel filtration. Two contained both binding and blocking antibodies against IF, one had only blocking antibodies and one lacked both types of antibodies. The antibodies were mainly of the IgG-type. No such antibodies were found in the urine of a healthy person. None of the urines studied contained enough protein to be classified as proteinuric. Not until the interferences of the autoantibodies in the IF assay can be eliminated is the assay of value in the diagnosis of PA.