Radioimmunoassay for Gastrin Employing Immunosorbent

Abstract

A solid phase radioimmunoassay for gastrin was established by covalent coupling of antibodies to bromoacetylcellulose. An antiserum monodisperse in respect to binding energy was employed. The effect of covalent coupling on antibody-binding energy, antibody utilization, specificity, and assay re-producibility was investigated by comparison with assays employing charcoal, polyethylene-glycol, or ion-exchange resin for separation. Specificity, within and between-assay reproducibility were of the same order for the four methods employed. A decrease in antibody-binding energy, expressed by the equilibrium constant K°, from 1.0 × 10¹² l/mol to 0.3 × 10¹² l/mol was observed after antibody coupling (mean of four batches). The final dilution of antiserum was 1:37,500 in assays using charcoal, polyethylene-glycol, and ion-exchange resin. The corresponding dilution in the antibody solid phase assay was 1:2000, resulting in a reduction of the number of gastrin determinations per ml antiserum from 15,000 to 800. It is concluded that a solid phase radioimmunoassay for gastrin of sufficient sensitivity may be established provided a surplus of antiserum of high binding energy is available.

Key Words:

• Antibodies
• charcoal
• gastrin
• immunosorbents
• ion-exchange resin
• polyethylene-glycol
• radioimmunoassay