Abstract: A conjugate useful in determining the amount of antigen or antibody in a liquid sample, said conjugate having a marker, an immunoreactive component (i.e. antigen or antibody) bound to the marker and an insolubilizing binding component which is also bound to the marker. The insolubilizing binding component portion of the conjugate will react with an insolubilizing receptor to form a solid product of conjugate and receptor unless the conjugate reacts with the corresponding antigen or antibody to be analyzed in which event the conjugate will not react with the insolubilizing receptor. The conjugate will be added to a liquid sample containing an unknown amount of, for example, an antibody. A known amount of the corresponding antigen is also added which reacts with both the conjugate and antibody. After the reaction is complete, the liquid sample is contacted with the insolubilizing receptor.