Blood group

An inherited feature on the surface of the red blood cells. A series of related blood types constitute a blood group system such as the Rh or the ABO system. The frequencies of the ABO and Rh blood types vary from population to population. In the US, the most common type is O+ (meaning O in the ABO system and positive in the Rh system) which is present in 37.4% of the population. The frequencies in the US (in descending order) are O+ (37.4%), A+ (35.7%), B+ (8.5%), O- (6.6%), A- (6.3%), AB+ (3.4%), B- (1.5%) and AB- (0.6%). In 1901 a Viennese pathologist named Karl Landsteiner (1868-1943) published an article entitled "On Agglutination Phenomena of Normal Human Blood," in which he observed that, when blood was transfused from one human to another, the body often clumped the transfused blood cells and rejected the transfusion, sometimes going in shock. In 1909 Landsteiner classified red blood cells into types A, B, AB and O and showed that the body rejects transfusions of a different blood type. After moving to the Rockefeller Institute in New York, Landsteiner received the Nobel Prize in 1930 for his pioneering research in immunology and blood grouping.

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1. A system of antigens under the control of closely linked allelic loci on the surface of the erythrocyte. Because of the antigenic differences existing between individuals, blood group s are significant in blood transfusions, maternal-fetal incompatibilities (hemolytic disease of the newborn), tissue and organ transplantation, disputed paternity cases, and in genetic and anthropologic studies; certain blood group s may be related to susceptibility or resistance to certain diseases. Often used as synonymous with blood type. See Blood Groups appendix for individual groups: ABO, Auberger, Diego, Duffy, I, Kell, Kidd, Lewis, Lutheran, MNSs, P, Rh, Sutter, Xg, and the low-frequency and high-frequency blood group s. 2. The classification of blood samples by means of laboratory tests of their agglutination reactions with respect to one or more blood group s. In general, a suspension of erythrocytes to be tested is exposed to a known specific antiserum; agglutination of the erythrocytes indicates that they possess the antigen for which the antiserum is specific. Certain antisera require special testing conditions.

- private b. a b. that is known to have occurred in only one family and is traceable to one single person.

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blood group n one of the classes (as A, B, AB, or O) into which individual vertebrates and esp. human beings or their blood can be separated on the basis of the presence or absence of specific antigens in the blood called also blood type

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any one of the many types into which a person's blood may be classified, based on the presence or absence of certain inherited antigens on the surface of the red blood cells. Blood of one group contains antibodies in the serum that react against the cells of other groups.

There are more than 30 blood group systems, one of the most important of which is the ABO system. This system is based on the presence or absence of antigens A and B: blood of groups A and B contains antigens A and B, respectively; group AB contains both antigens and group O neither. Blood of group A contains antibodies to antigen B; group B blood contains anti-A antibodies or isoagglutinin; group AB has neither antibody and group O has both. A person whose blood contains either (or both) of these antibodies cannot receive a transfusion of blood containing the corresponding antigens. The table illustrates which blood groups can be used in transfusion for each of the four groups.

Donor:               A          B         AB                0

Receives from:  A,0        B,0      A,B,AB,0       0

Gives to:           A,AB     B,AB   A,B               A,B,AB,0

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(blud grp) 2. an allotype (or phenotype) of erythrocytes defined by one or more cell surface antigens that are under the control of allelic genes. Antigenic determinants irregularly incite allotypic and sometimes xenotypic immune responses. Human blood groups are identified by agglutination supported by specific human or animal antisera and by lectins extracted from certain plants. An abbreviated classification of human blood groups is given in the accompanying table. 2. any of certain other characteristics or traits of a cellular or fluid component of blood, considered as the expression (phenotype or allotype) of the actions and interactions of dominant genes; used in medicolegal and other studies of human inheritance. Such characteristics include the antigenic groupings of erythrocytes, leukocytes, platelets, and plasma proteins. Called also blood type.