Monoclonal antibodies based sandwich erythro-immunoassay and 'dot' enzyme immunoassay for human chorionic gonadotropin in urine.

Two simple solid-phase sandwich immunoassays for human chorionic gonadotropin (hCG) employing monoclonal antibodies have been described. One is a sandwich erythro-immunoassay employing V-shaped well microtitration plates coated with monoclonal anti-beta-hCG antibody and monoclonal anti-alpha-hCG antibody labelled sheep erythrocytes. The second is a 'dot' enzyme immuno-assay employing dip-stick (plastic strips pasted with nitrocellulose pads) coated with monoclonal anti-beta-hCG antibody. Anti-alpha-hCG monoclonal-alkaline phosphatase conjugate was used to reveal hCG bound to solid surface. The assays can be performed by 'one-step' or 'two-step' procedures. Erythro-immunoassay as well as 'dot' enzyme immunoassay was able to detect in urine as low as 10 mIU hCG/ml. A good correlation was observed between the values obtained by these two methods as well as 'two-step' sandwich enzyme immunoassay on 47 urine samples.