Detection and quantification of natalizumab

Abstract

Methods and assays for detecting natalizumab in a sample, natalizumab-peptide complexes in a sample, and point-of-care devices for detecting natalizumab in a sample are described herein.

What is claimed is: 
     
         1 . A test device comprising:
 (a) a sample pad for receiving a sample from a subject, wherein the sample comprises an antibody or a fragment of the antibody;   (b) a conjugate pad; and   (c) a test membrane comprising a first test line comprising a peptide consisting of any one of SEQ ID NOs: 1, 2, 4, 13, 16, and 18-23.   
     
     
         2 . The test device of  claim 1 , wherein the conjugate pad comprises a detection reagent conjugated to the peptide in step (c). 
     
     
         3 . The test device of  claim 1 , wherein the conjugate pad comprises a detection reagent conjugated to an antibody specific for natalizumab. 
     
     
         4 . The test device of  claim 1 , wherein the conjugate pad comprises a detection reagent conjugated to:
 the peptide in step (c); and   an antibody specific for natalizumab.   
     
     
         5 . The test device of  claim 3 , wherein the antibody specific for natalizumab binds natalizumab at a variable region. 
     
     
         6 . The test device of  claim 3 , wherein the antibody specific for natalizumab binds natalizumab at a constant region. 
     
     
         7 . The test device of  claim 1 , wherein the test membrane further comprises a second test line comprising an antibody specific for the peptide in step (c). 
     
     
         8 . The test device of  claim 7 , wherein the antibody is natalizumab. 
     
     
         9 . The test device of  claim 1 , wherein the antibody is free, circulating natalizumab and not complexed to a protein prior to step (b). 
     
     
         10 . The test device of  claim 1 , wherein the first test line measures a bivalent form of the antibody. 
     
     
         11 . The test device of  claim 7 , wherein the second test line measures both bivalent and monovalent forms of the antibody. 
     
     
         12 . The test device of  claim 1 , wherein the test membrane comprises Western blot analysis, dot blot analysis, flow cytometry, enzyme-linked immunosorbent assay (ELISA), lateral flow immunoassay, radioimmunoassay (RIA), competitive immunoassay, dual antibody sandwich assay, chemiluminescent assay, bioluminescent assay, fluorescent assay, or agglutination assay. 
     
     
         13 . The test device of  claim 1 , wherein the first test line comprises a dual antibody sandwich assay. 
     
     
         14 . The test device of  claim 7 , wherein the second test line comprises a competitive immunoassay. 
     
     
         15 . The test device of  claim 1 , wherein the test membrane further comprises a control line. 
     
     
         16 . The test device of  claim 2 , wherein the detection reagent comprises colloidal gold. 
     
     
         17 . The test device of  claim 1 , wherein the sample is a biological fluid. 
     
     
         18 . The test device of  claim 17 , wherein the biological fluid comprises serum, plasma, whole blood, red blood cell concentrates, platelet concentrates, leukocytes concentrates, urine, cerebral spinal fluid, or sputum. 
     
     
         19 . The test device of  claim 17 , wherein the biological fluid contains antibody at a concentration of between about 0.5 mcg/mL to 120 mcg/mL. 
     
     
         20 . The test device of  claim 1 , wherein the test device is a lateral flow immunoassay (LFA) device.