The determination of the human IgE serum level by radioimmunological methods

A two-phase radiodiffusion method described by Rowe has been employed in determining the IgE level in humans. The principle of the method is the reaction of IgE of low concentration with the immune sera mixed in agar. The so developed invisible precipitate was reacted on agar plate with 125I-labelled antiimmune globuline. The anorganic iodine content of the labelled antiglobuline reagent was under 5%, its specific activity 300 μCi/mg. The rings produced by immune reaction came into visible by autoradiography. The IgE concentrations were calculated from the measured diameters of the rings on a calibration curve. For the standardization of the radioimmune method the IgE level of the sera was obtained with the help of Phadebas IgE kit serum samples. The radiodiffusion technique compared with the radiosorbent method of Phadebas IgE kit gave a good correlation, only less deviations were found in the small and high IgE levels. It was found that this method is appropriate for clinical application. If the serum is kept for longer periods misleadingly low values will be obtained. In mixed normal human sera the IgE level found was 200 IU. (D.E.)