Production and characterisation of antisera to diphenylhydantoin suitable for radioimmunoassay.

The effect of carrier protein, nature of hapten-carrier bridge, and density of hapten substitution on the immunogenicity of diphenylhydantoin (DPH) derivatives in rabbits is described. DPH-3-valerate-bovine serum albumin (BSA) with a hapten: protein ratio of 27: 1 yields antisera of high titre and specificity for DPH. An antiserum to DPH-valerate-BSA was employed to develop a rapid, sensitive, one stage double antibody radioimmunoassay suitable for clinical application to serum, saliva, and urine samples. The assay, using 14C-DPH as tracer, is accurate and precise over the range 0.5--50 mug DPH per ml. Results by radioimmunoassay correlate closely with those obtained by gas-liquid chromatography (r = 0.97).