Red Blood Cell Antibody Identification

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Também chamado: Alloantibody Identification; Antibody ID, RBC; Ab ID
Nome formal: Red Blood Cell Antibody Identification
Exames relacionados: Direct Antiglobulin; Indirect Antiglobulin; Blood Typing; Type and screen; Crossmatch

De relance

Por que fazer este exame?

To identify the specific antibody present when a direct antiglobulin test (DAT) or indirect antiglobulin test (IAT) is positive; to help identify the cause of a transfusion reaction or the cause of hemolytic disease of the newborn (HDN)

Quando fazer este exame?

When an IAT screening test is positive when performed as part of a prenatal workup or prior to a blood transfusion; when a person has a positive DAT following a suspected transfusion reaction or is suspected to have an autoimmune hemolytic anemia; when a newborn has HDN

Amostra:

A blood sample drawn from a vein in your arm

É necessária alguma preparação?

None

A amostra

O que está sendo pesquisado?

Antibodies to red blood cells (RBCs) can be produced by the body's immune system in response to being exposed to "foreign" RBC antigens, structures found on the surfaces of RBCs. This test identifies the specificity of red blood cell antibodies in the blood that were produced in response to a previous exposure to someone else's RBCs either through blood transfusion or prior pregnancy. It is often done as a follow up to a positive screening result by an indirect antiglobulin test (IAT) or when an antibody is detected attached to a patient's RBCs by a positive direct antiglobulin test (DAT).

The type of RBC antibodies that you may produce depends on the specific combination of surface antigens on your RBCs that you inherited from your parents. Normally your body will only produce antibodies directed against antigens not found on your own cells. The major RBC antigens are A, B and the Rh factor (D antigen). They determine a person's basic blood type (for more on this, see Blood Type and Blood Banking).

Our bodies naturally produce antibodies against the A and B antigens that we do not have on our red blood cells. For example, a person who is blood type A will have antibodies directed against B antigens and someone who is blood type B will have anti-A antibodies. A person who has blood type O lacks both of the A and B antigens on their red blood cells and will produce antibodies to both A and B antigens. Anti-A and anti-B antibodies are usually capable of rapidly hemolyzing red blood cells containing A or B antigens.

The Rh factor (D antigen) is a potent stimulus for antibody production. It is estimated that if an Rh negative person is exposed to only one or two drops of Rh positive blood, their immune system can be triggered to begin producing anti-D antibodies. For these reasons, blood that is to be transfused must be compatible with a person's ABO and Rh blood type; all blood donors and transfusion recipients are tested for ABO group and Rh type, and donated blood is only given to transfusion recipients of the same group and type.

 

Individual's ABO blood type Naturally occurring RBC antibodies
O Anti-A and anti-B
A Anti-B
B Anti-A
AB None

In addition to these major ABO and Rh blood group antigens, there are numerous other minor RBC blood group antigens, such as Kell, Kidd, Duffy, and other Rh antigens. Antibodies to these antigens are not made naturally and are only produced by the body when exposed to them through blood transfusion or when a mother is exposed to a baby's blood cells during pregnancy.

When a person with a RBC antibody is again exposed to RBCs bearing the "foreign" antigen, whether by another transfusion or pregnancy, the RBC antibodies may attach to the specific antigens on the foreign RBCs and target the RBCs for destruction. Depending on the antigen and antibody involved and the quantity of RBCs affected, this can cause a reaction ranging from mild to severe and potentially life-threatening. It may happen immediately, such as during a blood transfusion, or take longer, from one to several days following a transfusion. When antibodies attach to antigens, the red blood cells can be destroyed, termed hemolysis. This can occur within the blood vessels or in the liver or spleen and cause symptoms and signs such as fever, chills, nausea, flank pain, low blood pressure, bloody urine, and jaundice.

Antibody identification tests that detect antibodies directed against the minor RBC blood group antigens are not routinely done but are performed when the presence of an antibody is detected through a positive IAT or DAT.

Como a amostra é obtida para o exame?

A blood sample is obtained by inserting a needle into a vein in the arm.

NOTA: Se exames médicos em você ou em alguém importante para você o deixam ansioso ou constrangido, ou se você tem dificuldade de lidar com eles, leia um ou mais dos seguintes artigos: Lidando com dor, desconforto ou ansiedade durante o exame, Conselhos sobre exames de sangue, Conselhos para ajudar crianças durante exames médicos, and Conselhos para ajudar idosos durante exames médicos.

Outro artigo, Siga essa amostra, fornece uma visão da coleta e do processamento de uma amostra de sangue e de uma amostra de cultura da garganta.

É necessário algum preparo para garantir a qualidade da amostra?

No test preparation is needed.

O exame

Perguntas frequentes

Pergunte ao laboratório

* indica um campo necessário



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Fontes do artigo

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NOTA: Este artigo se baseia em pesquisas que incluíram as fontes citadas e a experiência coletiva de Lab Tests Online Conselho de Revisão Editorial. Este artigo é submetido a revisões periódicas do Conselho Editorial, e pode ser atualizado como resultado dessas revisões. Novas fontes citadas serão adicionadas à lista e distinguidas das fontes originais usadas.

Wu, A. (© 2006). Tietz Clinical Guide to Laboratory Tests, 4th Edition: Saunders Elsevier, St. Louis, MO. Pp 122-123.

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(© 2006-2008). Transfusion, Compatibility Testing. ClinLab Navigator [On-line information]. Available online at http://www.clinlabnavigator.com/transfusion/compatibilitytesting.html through http://www.clinlabnavigator.com. Accessed June 2009.

(Revised 1999 January). The Use of Human Blood and Blood Components. American Red Cross, Education Circular of Information [On-line information]. Available online at http://chapters.redcross.org/ca/socal/research/circular.html through http://chapters.redcross.org. Accessed June 2009.