Abstract: The present invention provides the use of a composition comprising an antigen recognizing molecule or fragment thereof and a lipid-based carrier for blocking an interaction between a ligand and a receptor.

Abstract: The standardization of a labelled constituent, such as anti-IgE, for use in a specific binding assay method is disclosed. The method involves standardizing a labelled ligand (eg., radiolabelled IgE) against a ligand reference substance (eg., WHO standard IgE) to determine the weight of IgE protein represented by the labelled ligand, expressed in terms of the reference substance (eg., WHO units). Anti-light chain antibodies are attached to a solid phase and contacted with varying concentrations of the labelled ligand to bind the ligand to the anti-light chain antibodies. The ligand is then contacted with the labelled constituent and the amount of labelled constituent, in relation to the amount of ligand protein present, expressed in terms of the reference substance, is determined. The labelled constituent is thus standardized, since the actual weight of a ligand can be determined from the amount of labelled constituent bound thereto.