Scavenger antibody mixture and its use for immunometric assay

• US 5,026,653 A
• Filed: 09/30/1987
• Issued: 06/25/1991
• Est. Priority Date: 04/02/1985
• Status: Expired due to Fees

• Current Assignee: Leeco Diagnostics, Inc. (Thermo Fisher Scientific Incorporated)
• Original Assignee: Leeco Diagnostics, Inc. (Thermo Fisher Scientific Incorporated)
• Inventors: Salcedo, F. Brad, Lee, Jin P., Robins, Martin F.
• Primary Examiner(s): NOT, DEFINED
• Assistant Examiner(s): Graeter, Janelle
• Application Number:
  US07/103,067
• Time in Patent Office: 1,364 Days
• Field of Search: 435/7, 435/810, 436/518, 436/548, 436/807, 436/814, 436/818, 436/825, 436/65, 436/87, 436/165, 436/166, 436/168, 436/170, 436/175, 422/58, 422/61
• US Class Current: 436/518
• CPC Class Codes: G01N 33/54393 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 Class Codes: G01N 33/577 involving monoclonal antibodies binding reaction mechanisms characterised by the use of monoclonal antibodies; monoclonal antibodies per se are classified with their corresponding antigens; G01N33/53 - G01N33/576 take precedence
• CPC Class Codes: G01N 33/76 Human chorionic gonadotropin including luteinising hormone, follicle stimulating hormone, thyroid stimulating hormone or their receptors
• CPC Class Codes: Y10S 435/962 Prevention or removal of interfering materials or reactants or other treatment to enhance results, e.g. determining or preventing nonspecific binding
• CPC Class Codes: Y10S 436/807 Apparatus included in process claim, e.g. physical support structures
• CPC Class Codes: Y10S 436/814 Pregnancy
• CPC Class Codes: Y10S 436/818 Human chorionic gonadotropin

Abstract

Provided is a test kit for conducting a membrane sandwich immunoassay of a multivalent antigen, optionally including reagents, the test kit includes a hollow container for reception of a fluid specimen, containing in series fluid absorbent body, a fluid pervious layer, and a fluid pervious solid membrane layer on which antibody is immobilized such that fluid added (e.g., labeled antibody and fluid specimen) to the container migrates through the membrane and in the presence of unlabeled scavenger antibody on the reactive surface of the membrane forms a multiple-site immunospecific antibody-antigen-antibody sandwich immobilized and labeled thereon, preferably in the form of a visible positive or negative indicator of the presence and/or amount of the analyte antigen in the specimen sample. The scavenger antibody serves to prevent false positive or other spurious reactions due to antigen analogs, antigen interference substances, or circulating human immnoglobulins.

Claims

1. A storage-stable reagent kit for immunoassay of the antigen human chorionic gonadotropin (hCG) in an aliquot of body fluid, comprising:

(a) as a first component, a label conjugated to an antibody which is immunospecific for the hCG antigen;

(b) as a second component, an antibody immobilized by solid support means, the immobilized antibody being immunospecific for the hCG antigen;

(c) a further component that is a scavenger antibody characterized by both low affinity for the hCG antigen and high affinity for the cross reactant analogs luteinizing hormone (LH), follicle stimulating hormone (FSH), and thyroid stimulating hormone (TSH), the scavenger antibody being present in an amount sufficient to prevent unwanted reactivity between the antibody of said first component and the antibody of said second component with said antigen cross reactant analog of the hCG antigen;

(d) detection means responsive to the label for determining the presence thereof;

the components being constituted such that, when subjected to liquid phase incubation with an aliquot containing the hCG antigen, the cross reactant analogs are scavenged and the first and second components become mutually bound at immunospecific binding sites with the hCG antigen in sandwich relation thereby preventing said cross reactivity and enabling separation of the bound hCG antigen in solid form free of non-specific antigen and unbound labeled antibody.

2. A kit as in claim 1, wherein at least one of said first component and said second components includes a monoclonal antibody.

3. A kit as in claim 1, wherein said scavenger antibody is a monoclonal antibody.

4. A kit as in claim 1, wherein said scavenger antibody is a polyclonal antibody.

5. A kit as in claim 1, wherein said scavenger antibody is further characterized by selectivity for the beta subunit of hCG.

6. A kit as in claim 1, wherein said second component comprises an antibody immunospecific for the hCG antigen and immobilized upon a generally planar support in an area defining a vertical line extending at least part way thereacross;

wherein said support further includes a reagent adapted to react so as to bind the tracer conjugated antibody of the first component thereto and substantially not reactive with hCG, said reagent bound to said support in an area defining a horizontal line intersecting the vertical line, whereby the immunoassay of a fluid containing hCG causes reaction of both of said lines so as to form a plus sign and immunoassay of a fluid containing substantially no hCG causes reaction only of said horizontal line so as to form a minus sign.

7. A sensitive, rapid, and accurate immunometric assay for the antigen hCG in a sample of body fluid, hCG having two distinct amino acid chain subunits designated as alpha and beta, which assay comprises:

(a) contacting the sample with a labeled antibody specific to the antigen to form a soluble labeled complex of the antibody and antigen;

(b) contacting the sample with at least one unlabeled soluble scavenger antibody characterized by low affinity for hCG and high affinity for cross reactive substances LH, FSH and TSH so as to prevent the formation of a complex between the labeled antibody and the cross reactive substances which are present in said sample;

(c) contacting the soluble complex with another antibody which is specific to the hCG antigen, said other antibody being bound to a solid carrier; and

(d) detecting the labeled antibody.

8. An assay as in claim 7, wherein the step of contacting the sample with a scavenger antibody comprises contacting the sample with a monoclonal antibody.

9. An assay as in claim 7, wherein the step of contacting the sample with a scavenger antibody comprises contacting the sample with an antibody having selectivity for the beta subunit of hCG.

10. An assay as in claim 7, wherein the step of contacting the sample with a scavenger antibody comprises contacting the sample with a polyclonal antibody.