AB0 System and Rh Factor: What exactly is the AB0 System?

These antigenes are not only on the erythrocyte surface , they are on many different cell systems in the body. Most people have the blood type 0, followed by groups A, B and AB.

Which antigenes and antibodies are present?

In people with type 0 blood none of the principal antigenes occur on the RBCs. Theoretically type 0 blood is a universal donor . This blood has antibodies against A and B. A person with AB blood has both A and B antigens on the RBCs. This blood contains no antibodies against A or B antigens. People with AB blood are also called universal recipients , because of the missing antibodies.

Note that a person born with one type of AB0 antigens has the antibodies against the other antigen, although they had never contact with the other type of blood.

What happens if a patient receives the “wrong” blood type?

Let me give you an example: If a patient with type A blood receives a unit of type B blood a severe hemolytic reaction would occur. The antibodies against the B antigen, which are present in the A client’s blood, attack the erythrocytes of the type B donor blood. The hemolysis of the RBCs causes the release of free hemoglobin into the blood stream, which can damage the renal tubules. A transfusion of incompatible blood may ultimately result in renal failure der Fehler, das Scheitern and death.

How about the Rh factor?

The Rhesus (Rh) system is also of great importance. It is named after the rhesus monkey used in the original research on this factor. The Rh system causes major haemolytic diseases of the newborn (HDN). Actually, there have been several different Rh factors identified, but usually only the main factor is clinically significant.

The Rh factor is also – like the AB0 system – genetically determined. In contrast to the AB0 system, a person with Rh-negative blood does not have antibodies against the Rh factor until there is sensitization.

How acts Rh-positive and Rh-negative to each other?

Usually a Rh-negative person doesn’t have any antibodies against the Rh factor. However, a Rh-negative man may become sensitized by transfusion with Rh-positive blood. In a Rh-negative woman, antibodies can also develop through a pregnancy in which the fetus is Rh-positive. Once a Rh-negative person has antibodies against the Rh factor, another transfusion with Rh-positive blood or another pregnancy with an Rh-positive fetus can have serious consequences.

What is the relevance of the Rh factor in pregnancy?

A Rh-negative mother and a Rh-positive father can produce an Rh-negative or a Rh-positive baby, depending on the gene passed from the father. Laboratory tests can be performed to determine

etw. bestimmen if the Rh-positive father has two positive genes for Rh or one positive and one negative (note that a Rh-positive mother can carry an Rh-negative fetus without any Rh-related problems). A really important problem occurs, when a Rh-negative mother is carrying a Rh-positive child. Hemolytic disease of the newborn (HDN), formerly called erythroblastosis fetalis, occurs when a Rh-negative mother produces antibodies against the Rh-positive RBCs of her fetus.

This is not a problem with the first pregnancy. The fetus is usually not affected because the mother has not had time to build antibodies against the Rh factor. However, at the time of the infant’s separation from the placenta (a full-term birth or an abortion ), some of the RBCs from the fetus enter the mother’s general circulation and trigger the production of antibodies against the Rh factor. Subsequent pregnancies of the Rh-negative mother with a Rh-positive fetus may cause problems because the woman’s serum now has produced antibodies against Rh-positive antigens.

What’s the validity of the Rh Antibody Titer Test?

With the Rh Antibody Titer Test one can monitor the course of a Rh-negative woman who is carrying a Rh-positive fetus. Given that the mother is in her second pregnancy and given that she did not receive Rho(D) immunoglobulin (RhoGAM) after her first pregnancy, the rise of the titer helps to determine whether medical intervention, such as exchange transfusions or an early delivery die Auslieferung, die Übergabe , is indicated.

BIBLIOGRAPHY 1. Stevens C: Clinical Immunology & Serology: A Laboratory Perspective, F. A. Davis Company, 1995 2. http://dict.leo.org 3. www.dict.cc 4. www.webster-dictionary.org

EXERCISE: 1. Mrs. Adams had a hemolytic transfusion reaction, possibly caus‧ed by incompatible blood. She had low back pain, fever and chills. The transfusion was stopped, and the unit of blood was returned to the laboratory. The med tech should save a urine specimen for which reason? a. The urine may need to be checked for free hemoglobin b. Circulatory overload may require use of a diuretic c. Dehydration must be prevented

2. Mrs. Blurrer who is Rh-negative, just delivered a healthy 7-lb (pound) baby boy who is Rh-positive. She was given an injection of RhoGAM. She asks the physician why she had the injection. Which of the following explanations by the physician would be accurate? “This injection a. gives you temporary antibodies against the Rh factor so that your body won’t make any on your own, which should still be present if you have another Rh-positive pregnancy.” b. helps your body to manufacture antibodies, so that if you have another pregnancy with an Rh-positive baby, there won’t be any problems.” c. helps to eliminate any antibodies that you might have gotten from this pregnancy so that the next pregnancy will be normal.”

Die Autorin: Carmen Lobitz mail@lobitz-seminare.de www.lobitz-seminare.de Carmen Lobitz ist freie Trainerin, Lehrerin und MTA. Sie gründete 1998 in Berlin lobitz seminare, die u.a. Englischseminare für Health Professionals anbieten.

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Lösung für Exercise:

Answer: 1 a Answer: 2 a

AB0 System and Rh Factor: What exactly is the AB0 System?

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