Continuous flow automated radioimmunoassay using antibodies attached to red blood cells

Continuous-flow automated radioimmunoassays can be performed using antibodies which have been attached to red blood cells with chromic chloride. To separate the antibody-bound labeled antigen from unbound labeled antigen the erythrocytes are aggregated by Polybrene and separated from the supernatant by decantation. For the determination of serum insulin levels the method was sensitive to within 2 μU/ml when operating at a sampling rate of 10/hr with a total assay time of 11/2 hr. (U.S.)