METHODS AND REAGENTS FOR THE DETERMINATION OF IMMUNOSUPPRESSIVE AGENTS

摘要

Assay methods and reagents for determining the presence or amount of immunophilin ligands and immunophilins thereof employing a recombinant fusion protein comprising (i) an immunosuppressant binding protein and (ii) a heterologous protein are disclosed. The recombinant fusion protein can also be employed for the evaluation of immunosuppressive activities of immunosuppressive agents in order to determine the efficacy of an immunosuppressive agent during the course of therapeutic treatment of a patient therewith. Preferably, the recombinant fusion protein comprises a macrolide immunosuppressive agent and CTP:CMP-3-deoxy-D-manno-octulosonate cytidylyl transferase. When employed in a binding assay format, the recombinant fusion protein provides higher reactivity for the immunophilin ligand under determination than does the native immunosuppressant binding protein. In particular, an immunosuppressant assay reagent comprising FK-506 binding protein (FKBP) and CKS immobilized to a solid support material provides a higher signal-to-noise ratio when employed in a competitive heterogeneous assay format than when native FKBP immobilized to a solid support material is employed in such assay format.