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2: Blood group antigens are surface markers on the red blood cell membrane
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Red blood cell antigens determine your blood group
The antigens expresd on the red blood cell determine an individual's blood group. The main two blood groups are called ABO (with blood types A, B, AB, and O) and Rh (with Rh D-positive or Rh D-ne
gative blood types).
The functions of many of the blood group antigens are not known, and if they are missing from the red blood cell membrane, there is no ill effect. This suggests that if the blood group antigens ud to have a function, e.g., one particular blood group antigen made red blood cells more resistant to invasion from a parasite, it is no longer relevant today.
But the prence or abnce of red blood cell antigens becomes extremely important when blood from different people mixes, e.g., when a patient receives a blood transfusion from a blood bank. This also happens when a mother becomes pregnant becau during labor, a small amount of fetal blood enters her circulation. In the circumstances, exposure to the foreign antigens on the red blood cells can trigger immune reactions.
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It is not possible to completely remove the danger of adver reactions when blood from two people mix, but the danger can be minimized. Before a blood transfusion takes place, the blood to be donated must be "typed and cross matched" with the patient's blood to ensure immune compatibility (e Chapter 3). In pregnancy, the risk of the mother's immune system attacking the foreign antigens prent on her fetus' red blood cells is prevented by giving the mother antibodies to cover fetal red bl
ood cell antigens and removing them from the mother's circulation before her immune cells find them (e Chapter 4).很久以前英文
Blood groups differ around the world
The distribution of the four ABO blood types, A, B, AB, and O, varies in populations
throughout the world. It is determined by the frequency of the three alleles of the ABO gene in different populations. Blood type O is the most common worldwide, followed by group
A. Group B is less common, and group AB is the least common.
Blood Groups and Red Cell Antigens
Blood Groups and Red Cell Antigens
The frequencies of ABO and Rh type in the United States were recently examined by collecting data from blood donors over a 10 year period (1). The charts below summarize the
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findings for blood type and race:The highest percentage of type O (57%) was found in Hispanic donors (a group that includes
donors of Mexican, Puerto Rican, and Cuban descent). The next highest percentage of type
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O was found in North American Indian (55%) and black (50%) donors.
Blood Groups and Red Cell Antigens
Blood Groups and Red Cell Antigens
In all donors, the Rh D-positive (RhD+) blood type was more common than the Rh D-negative (RhD-) blood type. The highest percentage of RhD- was found in white donors (17.3%).
Blood type O: the Americas有道海量
People with blood type O are said to be "universal donors" becau their blood is compatible with all ABO blood types. It is also the most common blood type in populations around the world, including the USA (1) and Western Europe (2, 3). Among indigenous populations of Central and South America, the frequency of O blood type is extremely high, approaching 100%. It is also high among Australian aborigines.
Blood Type A: Central and Eastern Europenacc
Type A is common in Central and Eastern Europe. In countries such as Austria, Denmark, Norway, and Switzerland, about 45-50% of the population have this blood type, whereas about 40% of Poles and Ukrainians do so.
The highest frequencies are found in small, unrelated populations. For example, about 80% of the Blackfoot Indians of Montana have blood type A.
Blood type B: Asia
Blood type B is relatively common in Chine and Indians, being prent in up to 25% of the population. It is less common in European countries and Americans of European origin, being found in about 10% of the populations.
Blood type AB is the least common
Blood type AB individuals are known as "universal receivers" becau they can receive blood from any ABO type.
It is also the rarest of the blood groups. It is most common in Japan, regions of China, and in Koreans, being prent in about 10% of the populations.The classification of blood cell antigens
Traditionally, newly discovered red blood cell antigens were named alphabetically (e.g.
ABO, MNS, P) or were named for the first person who produced antibody against them (e.g. Duffy, Diego). In 1980, The International Society of Blood Transfusion (ISBT) Working Party on Terminology for Red Cell Surface antigens was formed to create a standard for blood group terminology. Under this terminology, each blood group antigen has a number, and it belongs to a blood group system, a collection, or a ries (4).
Blood groups
A blood group system contains antigens controlled by a single gene (or by multiple cloly linked loci), and the system is genetically distinct. At the time of writing, there are 22 blood group systems, i
混淆英语ncluding the ABO, Rh, and Kell blood groups which contain antigens that can provoke the most vere transfusion reactions.
Each blood group antigen is assigned a six-digit number by the ISBT. The first three digits reprent the blood group (e.g., ABO is 001, Rh is 004), and the last three identify the
antigen in the order it was discovered. For example, for ABO, the A antigen was the first to be discovered and has the number 001.001 whereas the B antigen was next and is designated 001.002.
Blood Groups and Red Cell Antigens Blood Groups and Red Cell Antigens
Collections
A collection contains antigens that are related in some way, e.g., by genetics or
母亲节快乐用英语怎么说biochemistry, but they do not meet the criteria to form a blood group. Once a collection of
antigens can be proven to be genetically distinct, they are given the status of a blood group.
At the time of writing, there are six collections of antigens.
Series Blood Groups and Red Cell Antigens
Red cell antigens that do not fit into a blood group or a collection are sorted into two ries:
if they are rare (frequency of less than 1%), they are placed in the 700 ries, if they are
common (frequency greater than 90%), they are placed in the 901 ries. At the time of
writing, there are 22 antigens in the 700 ries and 11 antigens in the 901 ries.
References
1. Garratty G, Glynn SA, McEntire R. ABO and Rh(D) phenotype frequencies of different racial/
ethnic groups in the United States. Transfusion 2004;44:703–6. [PubMed: 15104651]
2. Bloodbook.Com, Racial & Ethnic Distribution of ABO Blood Types Cited 15th March, 2005.
3. Reid ME and Lomas-Francis C. The Blood Group Antigen Facts Book. Second ed. 2004, New
York: Elvier Academic Press.
4. Daniels GL, Fletcher A, Garratty G, Henry S, Jorgenn J, Judd WJ, Levene C, Lomas-Francis C,
Moulds JJ, Moulds JM, Moulds M, Overbeeke M, Reid ME, Rouger P, Scott M, Sistonen P, Smart
E, Tani Y, Wendel S, Zelinski T. Blood group terminology 2004: from the International Society of
Blood Transfusion committee on terminology for red cell surface antigens. Vox Sang 2004;87:304–
16. [PubMed: 15585029] Blood Groups and Red Cell Antigens
