ELISA for a Naturally-Occurring Soluble Truncated Form of IL-23 Receptor

Abstract

A naturally-occurring soluble truncated IL-23Rα protein (i.e., Δ9 IL-23Rα) is shown to be present in a biological sample and can serve as a diagnostic tool for autoimmune diseases. There is provided an enzyme-linked immunosorbent assay (ELISA) and test kit for the serological detection of the soluble truncated form of IL-23Rα protein. More particularly, antibody-sandwich ELISA method and kits for Δ9 IL-23Rα as an antigen were developed to detect Δ9 IL-23Rα levels in biological samples from a mammal and a human patient and are used as a diagnostic index. The present disclosed ELISA has utility as a diagnostic tool to detect Crohn's disease in patients using EDTA-plasma.

What is claimed is: 
     
         1 . A kit for detecting a Δ9 isoform of IL-23Rα, comprising: a) a first antibody that binds to carboxyl-terminal truncated Δ9 isoform of IL-23Rα, wherein the carboxyl-terminal truncated Δ9 isoform of IL-23Rα has the amino acids 318-348 of IL-23Rα; and; b) instructions for using the antibody for detecting Δ9 isoform of IL-23Rα, wherein said Δ9 isoform has an amino acid sequence of SEQ ID NO: 2. 
     
     
         2 . The kit of claim  11 , wherein said antibody is immobilized to a solid support. 
     
     
         3 . The kit of claim  11 , further comprising a second antibody that specifically binds to extracellular domain of IL-23Rα. 
     
     
         4 . The kit of claim  11 , wherein said first antibody is a monoclonal antibody and said second antibody is a polyclonal antibody. 
     
     
         5 . The kit of claim  11 , wherein said instructions provide guidance to the use of the kit to detect Δ9 isoform of IL-23Rα in a biological sample. 
     
     
         6 . The kit of claim  16 , wherein said biological sample is EDTA-plasma.