Abstract: The present invention provides for the quantification of a human, human-chimeric, humanized antibody, or a fragment thereof, without the necessity of using a target-specific molecule. More particularly, the invention relates to a quantification assay that includes the step of blocking non-specific binding sites of a capture reagent with a blocking buffer containing a non-human mammalian globulin, such as bovine gamma globulin (BGG).

Abstract: The invention is directed to a cross-screening system and methods of the invention utilizing a combination of an immunoassay (IA) and electrochemiluminescence assay (ECLA) to identify molecules that have binding affinities for a target molecule. The cross-screening system and methods of the invention can detect molecules that have binding affinities for the target molecule below the detection limits of the individual immunoassay or ECLA. The cross-screening system and methods of the invention are useful for generating a pool of candidate analyte molecules enriched in a desired characteristic, such as low binding affinity for a target molecule. Low affinity antibodies identified by the cross-screening system and methods of the invention are useful, for example, in assessing the safety and efficacy of biological therapeutics.