Modification of the Farr assay using ethanol-ammonium acetate precipitation and its application to the measurement of affinity of anti-HCG produced in several species.
A double isotope modified Farr assay was used to determine the total binding sites and affinity of antibodies to human chorionic gonadotrophin. Precipitation of the antigen--antibody complex at equilibrium with ammonium sulphate gave very high levels of nonspecific binding. Good discrimination over background was observed using a specific anti-immunoglobulin serum. However since we were interested in measuring the affinity of antibodies raised in several animal species it was more appropriate to use a single nonspecies precipitating reagent. We found that the use of a mixture of ethanol-ammonium acetate gave very low levels of non-specific binding in baboons, marmosets, rabbits and mice.
D000818:Animals; D000915:Antibody Affinity; D000917:Antibody Formation; D001666:Binding Sites, Antibody; D011232:Chemical Precipitation; D006063:Chorionic Gonadotropin / Q000276:immunology*; D000431:Ethanol; D008722:Methods; D000644:Quaternary Ammonium Compounds; D013045:Species Specificity
D006063:Chorionic Gonadotropin; D000644:Quaternary Ammonium Compounds; D000431:Ethanol