Immunoassay method less affected by impurities

Patent metadata

Field	Value
Publication number	US-9874558-B2
Application number	US-201314655998-A
Country	US
Kind code	B2
Filing date	Nov 15, 2013
Priority date	Dec 28, 2012
Publication date	Jan 23, 2018
Grant date	Jan 23, 2018

Abstract

An object of the present invention is to provide a method of measuring the amount of a compound containing a sugar chain in a biological sample by a sandwich immunoassay method using a labeled lectin, which method is suitable for reduction of noise originating from impurities and determination of the exact amount of a target compound. The present invention provides a method of measuring the amount of a target compound containing a sugar chain in a biological sample by a sandwich immunoassay method using a labeled lectin (including cases where a target compound-capturing substance other than an antibody is used as a ligand), the method containing adding a sugar chain compound which competes (crosses) with impurities contained in the biological sample in binding with the labeled lectin.

First claim

The invention claimed is:

1. A method of measuring the amount of a target compound comprising a sugar chain in a biological sample by a sandwich immunoassay method using a ligand selected from the group consisting of antibody, aptamer, synthetic peptide and receptor, and a labeled lectin, said method comprising
releasing a labeled lectin which is bound with impurities on a solid-phase by adding a sugar chain compound to allow said labeled lectin to bind to said sugar chain compound, and
removing said labeled lectin bound with said sugar chain compound to reduce the noise originating from the impurities bound with said labeled lectin,
wherein, when the dissociation constant between said sugar chain compound to be added and said labeled lectin and the dissociation constant between said target compound and said labeled lectin are defined as “x” and “a”, respectively, said x is in a range of x>a.

2. The method according to claim 1 , wherein said target compound comprising a sugar chain in said biological sample to be measured is a tumor marker.

3. The method according to claim 2 , wherein the combination of said target compound, said labeled lectin and said sugar chain compound to be added is any of the following combinations of (1) to (4):
(1) said target compound is a prostate-specific antigen (PSA), said labeled lectin is Trichosanthes japonica lectin (TJA-II), and said sugar chain compound to be added is a sugar chain compound containing fucose residue or a sugar chain compound containing galactose residue;
(2) said target compound is a prostate-specific antigen (PSA), said labeled lectin is Wisteria floribunda lectin (WFA), and said sugar chain compound to be added is a sugar chain compound containing fucose residue;
(3) said target compound is alpha-fetoprotein (AFP), said labeled lectin is Lens culinaris lectin (LCA), and said sugar chain compound to be added is a sugar chain compound containing mannose residue; and
(4) said target compound is alpha-fetoprotein (AFP), said labeled lectin is Sambucus sieboldiana lectin (SSA), and said sugar chain compound to be added is a sugar chain compound containing fucose residue.

4. The method according to claim 3 , wherein a solid-phase layer used for immobilizing said ligand on a support comprises a sugar chain compound, said method comprising adding a sugar chain compound different from said sugar chain compound.

5. The method according to claim 3 , comprising measuring florescence emitted by said labeled lectin by surface plasmon-field enhanced fluorescence spectroscopy (SPFS).

6. The method according to claim 4 , comprising measuring florescence emitted by said labeled lectin by surface plasmon-field enhanced fluorescence spectroscopy (SPFS).

7. The method according to claim 1 , wherein the combination of said target compound, said labeled lectin and said sugar chain compound to be added is any of the following combinations of (1) to (2): 1) said target compound is a prostate-specific antigen (PSA), said labeled lectin is Trichosanthes japonica lectin (TJA-II), and said sugar chain compound to be added is a sugar chain compound containing fucose residue or a sugar chain compound containing galactose residue; and (2) said target compound is a prostate-specific antigen (PSA), said labeled lectin is Wisteria floribunda lectin (WFA), and said sugar chain compound to be added is a sugar chain compound containing fucose residue.

8. The method according to claim 7 , wherein a solid-phase layer used for immobilizing said ligand on a support comprises a sugar chain compound, said method comprising adding a sugar chain compound different from said sugar chain compound.

9. The method according to claim 7 , comprising measuring florescence emitted by said labeled lectin by surface plasmon-field enhanced fluorescence spectroscopy (SPFS).

10. The method according to claim 8 , comprising measuring florescence emitted by said labeled lectin by surface plasmon-field enhanced fluorescence spectroscopy (SPFS).

11. The method according to claim 1 , wherein a solid-phase layer used for immobilizing said ligand on a support comprises a sugar chain compound, said method comprising adding a sugar chain compound different from said sugar chain compound.

12. The method according to claim 11 , comprising measuring florescence emitted by said labeled lectin by surface plasmon-field enhanced fluorescence spectroscopy (SPFS).

13. The method according to claim 1 , comprising measuring florescence emitted by said labeled lectin by surface plasmon-field enhanced fluorescence spectroscopy (SPFS).

14. The method according to claim 1 , wherein the combination of said target compound, said labeled lectin and said sugar chain compound to be added is any of the following combinations of (1) to (2): (1) said target compound is alpha-fetoprotein (AFP), said labeled lectin is Lens culinaris lectin (LCA), and said sugar chain compound to be added is a sugar chain compound containing mannose residue; and (2) said target compound is alpha-fetoprotein (AFP), said labeled lectin is Sambucus sieboldiana lectin (SSA), and said sugar chain compound to be added is a sugar chain compound containing fucose residue.

15. The method according to claim 14 , wherein a solid-phase layer used for immobilizing said ligand on a support comprises a sugar chain compound, said method comprising adding a sugar chain compound different from said sugar chain compound.

16. The method according to claim 14 , comprising measuring florescence emitted by said labeled lectin by surface plasmon-field enhanced fluorescence spectroscopy (SPFS).

17. The method according to claim 15 , comprising measuring florescence emitted by said labeled lectin by surface plasmon-field enhanced fluorescence spectroscopy (SPFS).

Assignees

• Konica Minolta Inc
• Konica Minolt Inc

Inventors

• Isoda Takeshi
• Kaneko Tomonori

Classifications

• G01N33/5758

  involving compounds serving as markers for tumours, cancers or neoplasias, e.g. cellular determinants, receptors, heat shock/stress proteins, A-protein, oligosaccharides or metabolites · CPC title

• G01N33/50

  Chemical analysis of biological material, e.g. blood, urine; Testing involving biospecific ligand binding methods; Immunological testing (measuring or testing processes involving enzymes or microorganisms, compositions or test papers therefor; processes for forming such compositions, condition responsive control in microbiological or enzymological processes C12Q) · CPC title

• G01N2333/4724

  Lectins · CPC title

• G01N33/54393 Primary

  Improving reaction conditions or stability, e.g. by coating or irradiation of surface, by reduction of non-specific binding, by promotion of specific binding · CPC title

• G01N21/648

  using evanescent coupling or surface plasmon coupling for the excitation of fluorescence · CPC title