Crosstalk inhibitors and their uses

An assay for determining the amount or presence of a plurality of target haptens, each competing for binding to its specific ligand receptor, with at least one hapten analogue on a hapten analogue conjugate, in a reaction mixture, said reaction mixture comprising

• (1) a plurality of hapten analogues corresponding to said plurality of target haptens, each said hapten analogue present as part of a hapten analogue conjugate, each of said hapten analogue conjugates comprising a binding site attached via a linkage site to a protein, polypeptide or label, wherein said binding site binds said ligand receptor, wherein each said binding site is different from each other said binding site, and wherein each said linkage site may be the same or different;
• (2) a plurality of ligand receptors, each said ligand receptor binding with only one of said plurality of target haptens and with said binding site of said hapten analogue and not with other of said haptens, and wherein at least one of said plurality of ligand receptors is an antibody;
• and
• (3) a fluid sample suspected of containing said target haptens, said assay comprising the steps of:
• adding to said reaction mixture at least one crosstalk inhibitor comprising at least one analogue of said linkage site, said crosstalk inhibitor under assay conditions competing equally or better than the linkage site of said hapten analogue conjugates for binding to said antibody and competing poorly or insignificantly with the binding site of said hapten analogue conjugates for binding to said antibody, said crosstalk inhibitor in an amount sufficient to reduce the amount of binding to the linkage site of said hapten analogue conjugates to said antibody, and
• determining the amount or presence of said plurality of target haptens in said reaction mixture.

A method for identifying a crosstalk inhibitor for a ligand analogue conjugate, wherein said ligand analogue conjugate comprises a binding site attached via a linkage site to a protein, polypeptide or label, and wherein said crosstalk inhibitor competes with said linkage site for binding to a ligand receptor, wherein said ligand receptor is an antibody which binds said linkage site, said method comprising the steps of:

• (a) making a potential crosstalk inhibitor comprising at least one analogue of a linkage site of a ligand analogue conjugate,
• (b) testing said potential crosstalk inhibitor by:
• (i) performing a first assay utilizing a first reaction mixture comprising said ligand analogue conjugate and a ligand receptor, wherein said ligand receptor binds said linkage site causing a false positive result;
• (ii) performing a second assay utilizing a second reaction mixture comprising said ligand analogue conjugate, said potential crosstalk inhibitor and said ligand receptor;
• (iii) comparing the results of said first assay and said second assay, so that no false positive result or a reduced false positive result in said second assay indicates that said potential crosstalk inhibitor is useful crosstalk inhibitor.