A homogeneous sol particle immunoassay for human chorionic gonadotrophin using monoclonal antibodies

A mixture of monoclonal antibodies against human chorionic gonadotrophin (HCG) from 2 different clones was used to develop a homogeneous sol particle immunoassay (SPIA) for HCG, with high discrimination against luteinizing hormone (LH). The optimization of this assay is described. The work resulted in a spectrophotometric and a visual reading version. In an evaluation of the tests with 348 urines from pregnant women, 530 urines of non-pregnant women of fertile age and 100 post-menopausal women, the spectrophotometric screening test was 100% correct in the groups of urines from pregnant women and from post-menopausal women, and 99.8% correct in the group of urines from non-pregnant women of fertile age. This spectrophotometric screening test required an incubation period of 1 h and detected 280 IU/1 HCG. The eye reading test required an incubation period of 2 h and was able to detect about 450 IU/1 HCG. This test showed 100% correct results in the group of urines from non-pregnant women and from post-menopausal women, and 99.1% correct results in the group of pregnant women. In both test versions HCG concentrations up to 200,000 IU/1 did not result in false negative reactions. Urines of non-pregnant women, with an added 1000 IU/1 LH, gave correct negative test results.