Assay of insulin antibodies produced by the guinea-pig

THE antigenic properties of insulin are now well recognized, but no simple method has yet been described for the routine detection and assay of insulin antibodies. The method described here is based on the classical observation by Berson, Yalow, Bauman, Rothschild and Newerly1. They showed that during chromato-electrophoresis on filter paper, 131I-labelled insulin bound by insulin antibodies in human serum moves with the β-γ-globulins, while free insulin remains fixed at the point of application of the serum-insulin mixture on the filter paper. When an excess of unlabelled insulin mixed with a trace of labelled hormone is added to the anti-insulin serum, the excess insulin is adsorbed from solution by cellulose and the amount bound by the antibodies is measured in the supernatant solution. We have used this assay system for serum obtained from guinea-pigs treated with bovine insulin2 and capable of neutralizing insulin at rates ranging from 0.1 to 3.5 units per ml. serum. It can, however, be adapted for the detection and assay of antibody concentrations lower than this; it has not yet been used for anti-insulin sera of other animals or of man.