Specificity of antisera to oestrone determined by different radioimmunoassay methods

The specificity of an antisera to oestrone which was raised with oestrone-6-(O-carboxymethyl) oxime bovine serum albumin conjugate has been tested using different radioimmunoassay methods. Cross reactivity tests were made using (i) the liquid phase radioimmunoassay technique involving dextran coated charcoal, (ii) the double antibody precipitation technique, (iii) the solid phase method using polystyrene tubes, and (iv) the solid phase procedure using Enzacryl AA. The specificity of the oestrone antisera to the various steroids tested, assessed as percentage cross reaction against oestrone, was found to vary when determined by different radioimmunoassay methods. The results suggest that a choice of radioimmunoassay technique may be made such that a particular method would enable higher specificity to be obtained towards certain cross reacting steroids.