RIA/IRMA (coated tubes)
RIA: The RIAs with coated tubes are competitive ligand assays for detection of antibodies and antigens. The intensity of the radioactive radiation is inversely proportional to the concentration of the specific antibodies or the antigen in the patient sample. The quantitative evaluation of the antigen/antibody concentration is performed based on a calibration curve.
IRMA (immunoradiometric assays): The test principle is based on monoclonal antibodies bound directly or indirectly to the inner wall of the polystyrene tubes. The patient samples to be investigated are incubated together with monoclonal I-125-labelled antibodies in the coated tubes. The antigen in the patient samples is bound both by the immobilised antibodies and the I-125-labelled antibodies. A solid-phase bound sandwich complex is formed. The unbound I-125-labelled antibodies are removed by washing and subsequent decanting. The intensity of the radioactive radiation is proportional to the concentration of the antigens in the patient serum. The quantitative evaluation of the antigen concentration is performed based on a calibration curve.