Blood Group Testing
The ABO system is a test to determine an individual's blood type. According to MedlinePlus.com, a service of the National Institute of Health, this test is performed for a variety of reasons. Most frequently the test is used for those who will be receiving blood from a donor.
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Identification
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Austrian scientist Carl Landsteiner viewed blood cells under a microscope, and observed two distinctly different molecules which he named "A" and "B." He concluded that human blood has one or both of these molecules, but in some blood they are absent entirely. The four blood groups were then named A, B, AB and O, after the presence or absence of the molecules.
Types of blood
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If a person has type A blood, the plasma portion of the blood contains antibodies, which are prepared to attack type B blood. Likewise, type B blood will combat type A antigens, if they are present. AB blood has both A and B antigens, and does not contain antibodies against either one. If blood does not contain A or B antigens, it is type O.
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Tests
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To determine which type of blood a person has, a sample is taken and mixed with antibodies against A and B molecules. The blood will clump together if there is a reaction with one of the antibodies. Blood type is also determined by viewing a sample of the blood under a microscope to see which molecules, if any, are present.
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References
- Photo Credit blood testing image by John Keith from Fotolia.com
