FACTOID # 15: A mere 0.8% of West Virginians were born in a foreign country.
 
 Home   Encyclopedia   Statistics   States A-Z   Flags   Maps   FAQ   About 
   
 
WHAT'S NEW
 

SEARCH ALL

FACTS & STATISTICS    Advanced view

Search encyclopedia, statistics and forums:

 

 

(* = Graphable)

 

 


Encyclopedia > Coombs test

Coombs test (also known as Coombs' test, antiglobulin test or AGT) refers to two clinical blood tests used in [[immunohematology] and immunology. AGT may stand for: Alberta Government Telephones Adventure Game Toolkit The National Rail code for Aldrington railway station, United Kingdom. ... See drugs, medication, and pharmacology for substances that treat patients. ... Blood tests are laboratory tests done on blood to gain an appreciation of disease states and the function of organs. ... Immunology is a broad branch of biomedical science that covers the study of all aspects of the immune system in all organisms. ...


The two Coombs tests are:

  • Direct Coombs test (also known as direct antiglobulin test or DAT).
  • Indirect Coombs test (also known as indirect antiglobulin test or IAT).

The direct Coombs test is used to detect red blood cells sensitized with igG alloantibody, IgG autoantibody, and complement proteins. It detects antibodies bound to the surface of red blood cells in vivo. The red blood cells (RBCs) are washed (removing the patient's own plasma) and then incubated with antihuman globulin (also known as "Coombs reagent"). If this produces agglutination of the RBCs, the direct Coombs test is positive. DAT can mean: day after tomorrow, a J-Pop band. ... IAT may refer to: The Royal International Air Tattoo air display In computer programming, the Import Address Table The Harvard Implicit Association Test for demonstrating conscious-unconscious psychological divergences. ... Each antibody binds to a specific antigen; an interaction similar to a lock and key. ... Human red blood cells Red blood cells are the most common type of blood cell and are the vertebrate bodys principal means of delivering oxygen to body tissues via the blood. ... For the music festival, see Agglutination Metal Festival. ...


The indirect Coombs test is used in prenatal testing of pregnant women, and in testing blood prior to a blood transfusion. It detects antibodies against RBCs that are present unbound in the patient's serum. In this case, serum is extracted from the blood, and the serum is incubated with RBCs of known antigenicity. If agglutination occurs, the indirect Coombs test is positive.[1] Human blood smear: a - erythrocytes; b - neutrophil; c - eosinophil; d - lymphocyte. ... Blood transfusion is the process of transferring blood or blood-based products from one person into the circulatory system of another. ... Look up Serum in Wiktionary, the free dictionary. ... For the server security software, see Microsoft Forefront. ...

Contents

Mechanism

The two Coombs tests are based on the fact that anti-human antibodies, which are produced by immunizing non-human species with human serum, will bind to human antibodies, commonly IgG or IgM. Animal anti-human antibodies will also bind to human antibodies that may be fixed onto antigens on the surface of red blood cells (also referred to as RBCs), and in the appropriate test tube conditions this can lead to agglutination of RBCs. The phenomenon of agglutination of RBCs is important here, because the resulting clumping of RBCs can be visualised; when clumping is seen the test is positive and when clumping is not seen the test is negative. Each antibody binds to a specific antigen; an interaction similar to a lock and key. ... Blood plasma is the liquid component of blood, in which the blood cells are suspended. ... Molecular surface of an IgG molecule Immunoglobulin G(IgG) is a monomeric immunoglobulin, built of two heavy chains γ and two light chains. ... IgM (Immunglobulin M) antibody molecule consisting of 5 base units. ... “Red cell” redirects here. ... Agglutination is the clumping of particles. ... “Red cell” redirects here. ... “Red cell” redirects here. ...


Common clinical uses of the Coombs test include the preparation of blood for transfusion in cross-matching, screening for atypical antibodies in the blood plasma of pregnant women as part of antenatal care, and detection of antibodies for the diagnosis of immune-mediated haemolytic anaemias. Blood transfusion is the process of transferring blood or blood-based products from one person into the circulatory system of another. ... In medicine, Cross-matching refers to the process of performing blood tests to determine the similarity between two different blood types. ... Blood plasma is the liquid component of blood, in which the blood cells are suspended. ... A pregnant woman Pregnancy is the process by which a mammalian female carries a live offspring from conception until it develops to the point where the offspring is capable of living outside the womb. ... Obstetrics (from the Latin obstare, to stand by) is the surgical specialty dealing with the care of a woman and her offspring during pregnancy, childbirth and the puerperium (the period shortly after birth). ... Hemolysis (alternative spelling haemolysis) is the excessive breakdown of red blood cells. ...


Coombs tests are done on serum from venous blood samples which are taken from patients by venipuncture. The venous blood is taken to a laboratory (or blood bank), where trained scientific technical staff do the Coombs tests. The clinical significance of the result is assessed by the physician who requested the Coombs test, perhaps with assistance from a laboratory-based hematologist. Venipuncture using a vacutainer. ... The Doctor by Luke Fildes This article is about the term physician, one type of doctor; for other uses of the word doctor see Doctor. ... A physician specialising in the treatment of blood diseases. ...

Schematic showing the direct and indirect Coombs tests.
Schematic showing the direct and indirect Coombs tests.

Image File history File links Download high resolution version (950x890, 265 KB) Summary Description: schematic of the Coombs (or antiglobulin) test, showing what is performed and the micro- and macroscopic changes that occur. ... Image File history File links Download high resolution version (950x890, 265 KB) Summary Description: schematic of the Coombs (or antiglobulin) test, showing what is performed and the micro- and macroscopic changes that occur. ...

Direct Coombs Test

The direct Coombs test (also known as the direct antiglobulin test or DAT) is used to detect if antibodies or complement system factors have bound to RBC surface antigens in vivo. The DAT is not currently required for pre-transfusion testing but may be included by some laboratories. In vivo (Latin for (with)in the living). ...


Examples of diseases that give a positive direct Coombs test

The direct Coombs test is used clinically when immune-mediated hemolytic anemia (antibody-mediated destruction of RBCs) is suspected. A positive Coombs test indicates that an immune mechanism is attacking the patient's own RBC's. This mechanism could be autoimmunity, alloimmunity or a drug-induced immune-mediated mechanism. Hemolytic anemia is anemia due to hemolysis, the abnormal breakdown of red blood cells either in the blood vessels (intravascular hemolysis) or elsewhere in the body (extravascular). ... Autoimmunity is the failure of an organism to recognize its own constituent parts (down to the sub-molecular levels) as self, which results in an immune response against its own cells and tissues. ... Alloimmunity is a condition in which the body gains immunity against cells from another individual of the same species. ...


Examples of alloimmune hemolysis

Hemolytic disease of the newborn, also known as HDN, is an alloimmune condition that develops in a fetus, when the IgG antibodies that have been produced by the mother and have passed through the placenta include ones which attack the red blood cells in the fetal circulation. ... Rh disease (also known as Rh (D) disease, Rhesus disease, RhD Haemolytic Disease of the Newborn, Rhesus D Haemolytic Disease of the Newborn or RhD HDN) is one of the causes of hemolytic disease of the newborn (also known as HDN). ... ABO blood group incompatibility and sensitisation is one cause of hemolytic disease of the newborn. ... Hemolytic disease of the newborn (anti-Kell1) is the second most common cause of severe hemolytic diseases of newborns (HDN) after Rh disease. ... Hemolytic disease of the newborn (anti-Rhc) can range from a mild to a severe disease. ... Blood transfusion is the process of transferring blood or blood-based products from one person into the circulatory system of another. ...

Examples of autoimmune hemolysis

Warm Antibody Autoimmune Hemolytic Anemia (AIHA) is the most common of the autoimmune hemolytic diseases. ... Evans Syndrome is an autoimmune disease in which an individuals antibodies attack their own RBCs as well as their platelets. ... Idiopathic cold hemagglutinin syndrome (CHAD) is a disease of humans. ... An autoimmune disease like paroxysmal nocturnal hemoglobinuria (PNH). ...

Drug-induced immune-mediated haemolysis

  • Methyldopa (IgG mediated type II hypersensitivity)
  • Penicillin (high dose)
  • Quinidine (IgM mediated activation of classical complement pathway and Membrane attack complex, MAC)

(A memory device to remember that the DAT tests the RBCs and is used to test infants for haemolytic disease of the newborn is:
Rh Disease; R = RBCs, D = DAT.) Methyldopa or alpha-methyldopa (brand names Aldomet, Apo-Methyldopa, Dopamet, Novomedopa) is a centrally-acting antiadrenergic antihypertensive medication. ... For the Japanese rock band, see Penicillin (band). ... Quinidine is a pharmaceutical agent that acts as a class I antiarrhythmic agent in the heart. ... Not to be confused with pneumonic. ...


Laboratory method

The patient's red blood cells (RBCs) are washed (removing the patient's own serum) and then incubated with antihuman globulin (also known as Coombs reagent). If immunoglobulin or complement factors have been fixed on to the RBC surface in-vivo, the antihuman globulin will agglutinate the RBCs and the direct Coombs test will be positive. (A visual representation of a positive direct Coombs test is shown in the upper half of the schematic). Human red blood cells Red blood cells are the most common type of blood cell and are the vertebrate bodys principal means of delivering oxygen to body tissues via the blood. ... Blood plasma is the liquid component of blood, in which the blood cells are suspended. ... Coombs test (also known as Coombs test, antiglobulin test or AGT) refers to two clinical blood tests used in hematology and immunology. ... In vivo (Latin for (with)in the living). ... Agglutination is the clumping of particles. ...


Indirect Coombs test

The indirect Coombs test (also known as the indirect antiglobulin test or IAT) is used to detect in-vitro antibody-antigen reactions. It is used to detect very low concentrations of antibodies present in a patient's plasma/serum prior to a blood transfusion. In antenatal care, the IAT is used to screen pregnant women for antibodies that may cause hemolytic disease of the newborn. The IAT can also be used for compatibility testing, antibody identification, RBC phenotyping, and titration studies. Wiktionary has a definition of: In vitro In vitro (Latin: within glass) means within a test tube, or, more generally, outside a living organism or cell. ... Hemolytic disease of the newborn, also known as HDN, is an alloimmune condition that develops in a fetus, when the IgG antibodies that have been produced by the mother and have passed through the placenta include ones which attack the red blood cells in the fetal circulation. ... In medicine, Cross-matching refers to the process of performing blood tests to determine the similarity between two different blood types. ...


Examples of clinical uses of the indirect Coombs test

Blood transfusion preparation

Main article: blood transfusion

The indirect Coombs test is used to screen for antibodies in the preparation of blood for blood transfusion. The donor's and recipient's blood must be ABO and Rhesus D compatible. Donor blood for transfusion is also screened for infections in separate processes. Blood transfusion is the process of transferring blood or blood-based products from one person into the circulatory system of another. ... Human blood smear: a - erythrocytes; b - neutrophil; c - eosinophil; d - lymphocyte. ... Blood transfusion is the process of transferring blood or blood-based products from one person into the circulatory system of another. ... Abo may refer to: Ã…bo, the Swedish name for Turku in Finland. ...

  • Antibody screening

A blood sample from the recipient and a blood sample from every unit of donor blood are screened for antibodies with the indirect Coombs test. Each sample is incubated against a wide range of RBCs that together exhibit a full range of surface antigens (ie blood types). A donor in general is a person that donates something. ... A blood type is a description an individuals characteristics of red blood cells due to substances (carbohydrates and proteins) on the cell membrane. ...

  • Cross matching
Main article: cross-matching

The indirect Coombs test is used to test a sample of the recipient's serum against a sample of the blood donor's RBCs. This is sometimes called cross-matching blood. In medicine, Cross-matching refers to the process of performing blood tests to determine the similarity between two different blood types. ... Blood donation is a process by which a blood donor voluntarily has blood drawn for storage in a blood bank for subsequent use in a blood transfusion. ... In medicine, Cross-matching refers to the process of performing blood tests to determine the similarity between two different blood types. ...


Antenatal antibody screening

The indirect Coombs test is used to screen pregnant women for IgG antibodies that are likely to pass through the placenta into the foetal blood and cause haemolytic disease of the newborn. Schematic of antibody binding to an antigen An antibody is a protein complex used by the immune system to identify and neutralize foreign objects like bacteria and viruses. ... Wikipedia does not yet have an article with this exact name. ... The placenta is an ephemeral (temporary) organ present in female placental vertebrates during gestation (pregnancy), but a placenta has evolved independently also in other animals as well, for instance scorpions and velvet worms. ... Rh disease (also Rhesus disease, Haemolytic Disease of the Newborn (HDNB) or Morbus haemolyticus neonatorum) is a condition that occurs when a Rh negative mother has given birth to a Rh positive baby and subsequently becomes pregnant with another Rh positive child. ...


Laboratory method

The IAT is a two-stage test. (A cross match is shown visually in the lower half of the schematic as an example of an indirect Coombs test).


First stage

Washed test red blood cells (RBCs) are incubated with a test serum. If the serum contains antibodies to antigens on the RBC surface, the antibodies will bind onto the surface of the RBCs. Human red blood cells Red blood cells are the most common type of blood cell and are the vertebrate bodys principal means of delivering oxygen to body tissues via the blood. ... Wikipedia does not yet have an article with this exact name. ... An antigen is any molecule that is recognized by antibodies. ...


Second stage

The RBCs are washed three or four times with isotonic saline and then incubated with antihuman globulin. If antibodies have bound to RBC surface antigens in the first stage, RBCs will agglutinate when incubated with the antihuman globulin (also known Coombs reagent) in this stage, and the indirect Coombs test will be positive. Coombs test (also known as Coombs test, antiglobulin test or AGT) refers to two clinical blood tests used in hematology and immunology. ...


Titrations

By diluting a serum containing antibodies the quantity of the antibody in the serum can be gauged. This is done by using doubling dilutions of the serum and finding the maximum dilution of test serum that is able to produce agglutination of relevant RBCs.


Coombs reagent

Coombs reagent (also known as Coombs antiglobulin or antihuman globulin) is used in both the direct Coombs test and the indirect Coombs test. Coombs reagent is antihuman globulin. It is made by injecting human globulin into animals. Coombs reagent contains animal antibodies specific for human immunoglobulins and human complement system factors. More specific Coombs reagents or monoclonal antibodies can be used. Globulin is one of the two types of serum proteins, the other being albumin. ... Schematic of antibody binding to an antigen An antibody is a protein complex used by the immune system to identify and neutralize foreign objects like bacteria and viruses. ... A complement protein attacking an invader. ... // Monoclonal antibodies (mAb) are antibodies that are identical because they were produced by one type of immune cell and are all clones of a single parent cell. ...


Enhancement Media

Both IgM and IgG antibodies react strongly with their antigens. IgG antibodies are most reactive at 37° C. IgM antibodies are easily detected in saline at room temperature as IgM antibodies are able to bridge between RBC’s owing to their large size, efficiently creating what is seen as agglutination. IgG antibodies are smaller and require assistance to bridge well enough to form a visual agglutination reaction. Reagents used to enhance IgG detection are referred to as potentiators. RBCs have a net negative charge called zeta potential which causes them to have a natural repulsion for one another. Potentiators reduce the zeta potential of RBC membranes. Common potentiators include low ionic strength solution (LISS), albumin, polyethylene glycol (PEG), and proteolytic enzymes. IGM might be an acronym or abbreviation for: The polymeric immunoglobulin, IgM International Grandmaster, a chess ranking intergalactic medium Intragroup medium - see: Intracluster medium IG Metall - the dominant German metalworkers union IGM is an acronym created by Robinson Technologies for several early BBS door games, including Legend of the Red... Schematic of antibody binding to an antigen An antibody is a protein complex used by the immune system to identify and neutralize foreign objects like bacteria and viruses. ... Wikipedia does not yet have an article with this exact name. ... For the server security software, see Microsoft Forefront. ... Schematic of antibody binding to an antigen An antibody is a protein complex used by the immune system to identify and neutralize foreign objects like bacteria and viruses. ... Saline may refer to: Salinity Saline (medicine) Saline, Michigan Saline, Scotland - a village in the burgh of Fife, Scotland. ... Room temperature describes a certain temperature within enclosed space that is uses for various purposes by human beings. ... For the music festival, see Agglutination Metal Festival. ... For the music festival, see Agglutination Metal Festival. ... Neuraminidase ribbon diagram An enzyme (in Greek en = in and zyme = blend) is a protein, or protein complex, that catalyzes a chemical reaction and also controls the 3D orientation of the catalyzed substrates. ...


History of the Coombs test

The Coombs test was first described in 1945 by Cambridge immunologists Robin Coombs (after whom it is named), Arthur Mourant and Rob Race.[2] Historically, it was done in test tubes. Today, it is commonly done using microarray and gel technology. Year 1945 (MCMXLV) was a common year starting on Monday (link will display the full calendar). ... Geography Status City (1951) Region East of England Admin. ... Immunology is a broad branch of biomedical science that covers the study of all aspects of the immune system in all organisms. ... Robert Royston Amos (Robin) Coombs (1921-), British physician and immunologist, co-discoverer of the Coombs test used for testing the presence of antigens (antiglobulins) in Rh disease. ... A test tube (Sometimes culture tube) is a kind of laboratory glassware, composed of a fingerlike length of glass tubing, open at the top, sometimes with a rounded lip at the top, and a rounded U shaped bottom. ... To meet Wikipedias quality standards, this article or section may require cleanup. ...


References

  1. ^ F. Rosen and R. Geha, Case Studies in Immunology, 4th ed., Garland Science, p.173.
  2. ^ Coombs RRA, Mourant AE, Race RR. A new test for the detection of weak and "incomplete" Rh agglutinins. Brit J Exp Path 1945;26:255-66.

External links

  • Coombs testing - Institute for Transfusion Medicine.
  • Coombs’ test - direct - Medlineplus.org.
  • Coombs’ test - indirect - Medlineplus.org.
  • Acute Anemia - emedicine.com
  • Drugs that cause haemolytic anemia - Merck Manual.

  Results from FactBites:
 
Coombs' Test - Tests, Test Results & Diagnosis - NY Times Health Information (830 words)
The direct Coombs' test is used to detect autoantibodies on the surface of red blood cells.
This test is sometimes performed to diagnose the cause of anemia or jaundice.
An abnormal (positive) indirect Coombs' test means you have antibodies that the body views as foreign.
  More results at FactBites »

 
 

COMMENTARY     


Share your thoughts, questions and commentary here
Your name
Your comments

Want to know more?
Search encyclopedia, statistics and forums:

 


Press Releases |  Feeds | Contact
The Wikipedia article included on this page is licensed under the GFDL.
Images may be subject to relevant owners' copyright.
All other elements are (c) copyright NationMaster.com 2003-5. All Rights Reserved.
Usage implies agreement with terms, 1022, m