Automated direct serum radioimmunoassay

Claim 1

In a process for automated radioimmunoassay of an antigen sample by flowing the sample through a chamber containing an immobilized immunoadsorbent composed of particulate substrate having antibodies specific to the antigen covalently bound thereto, and wherein the sample contains proteins tending to plug up the particulate substrate, the improvement comprising: diluting the sample to a consistency for free unplugged flow through the immobilized immunoadsorbent, preincubating the sample with an antibody specific to the antigen in said sample being assayed together with a known amount of a radioactive labelled antigen to form a mixture including (a) unlabelled antigen bound to the antibody, (b) labelled antigen bound to the antibody, (c) free unbound unlabelled antigen, and (d) free unbound labelled antigen; providing a chamber containing an immobilized immunoadsorbent including a solid particulate substrate having covalently bound thereto an antibody specific to said antigen and in an amount in excess of the sum of the free unbound labelled and unlabelled antigen, flowing said mixture through said chamber to form two fractions, one of which is the free unbound labelled and unlabelled antigen bound to the antibody on said substrate and the second being the labelled and unlabelled antigen bound to the antibody during the preincubation step, whereby said second fraction passes through said chamber and said first fraction binds to the immobilized immunoadsorbent, flowing an eluting solution through said chamber to effect release of said first fraction, counting the radioactivity of at least one or both of the fractions leaving said chamber as a function of the quantity of the antigen sought to be assayed in said sample and rinsing the chamber for subsequent assays of other samples of the same antigen.