An antigen is a molecule that triggers a specific immune response against itself when it enters the body, while an antibody is a protein produced by the immune system that is capable of binding with high specificity to an antigen
The ABO blood group system was discovered by Austrian immunologist Karl Landsteiner in 1901
The A and B antigens are inherited from both parents, dividing individuals into four major blood types
The ABO blood group antigens (agglutinogens) are attached to oligosaccharide chains that project above the RBC surface, with blood type O being the most common worldwide
The A and B antigens are the most important of the more than 100 different blood group antigens identified
Two groups of antigens can cause transfusion reactions more than others: ABO and Rh systems of antigens
Agglutinins, the antibodies, are gamma globulins, with most of them being IgM and IgG immunoglobulin molecules
High levels of agglutinins are found in the plasma of people who have never been exposed to a different type of blood, considered naturally occurring antibodies
If a recipient with blood group A is transfused with group B RBCs, the anti-B antibodies in the recipient's serum bind to the corresponding antigens on the transfused RBCs, causing rapid intravascular hemolysis
Mismatched transfusions can lead to acute kidney failure due to the release of large amounts of hemoglobin from ruptured donor erythrocytes
The Rh blood group system has over 50 antigens, with D being the most antigenic component, significantly more antigenic than the other Rh antigens
The D antigen is the most immunogenic, making it most likely to cause a transfusion reaction in the recipient
In the Rh system, the presence or absence of the D antigen is designated as Rh-positive or Rh-negative, respectively
In the A-B-O system, plasma agglutinins cause transfusion reactions spontaneously, while in the Rh system, spontaneous agglutinins almost never occur
To develop enough agglutinins in the Rh system to cause a significant transfusion reaction, a person must first be massively exposed to an Rh antigen, such as through a blood transfusion containing the Rh antigen
When red blood cells (RBCs) containing the Rh factor are injected into an Rh-negative person, anti-Rh agglutinins develop slowly, reaching maximum concentration about 2 to 4 months later
With multiple exposures to the Rh factor, an Rh-negative person eventually becomes strongly "sensitized" to the Rh factor, leading to enhanced and potentially severe transfusion reactions with subsequent transfusions of Rh-positive blood
Erythroblastosis fetalis, also known as "Hemolytic Disease of the Newborn," is a disease characterized by agglutination and phagocytosis of the fetus's red blood cells, particularly significant when an Rh-negative mother carries an Rh-positive fetus
In Erythroblastosis fetalis, maternal anti-Rh antibodies can cause agglutination of the fetus's blood, leading to hemolysis, jaundice in the baby, and potential damage to other cells in the body
Erythroblastosis fetalis results in severe anemia at birth, with the destruction of red blood cells by maternal anti-Rh agglutinins potentially causing permanent mental impairment or damage to motor areas of the brain in surviving infants
Prevention of sensitization to the D antigen in Rh-negative women who deliver Rh-positive babies is achieved through the administration of the anti-D antibody (RhoGAM) to prevent the development of large amounts of D antibodies during subsequent pregnancies
An antigen is a molecule that triggers a specific immune response against itself when it enters the body, while an antibody is a protein produced by the immune system that is capable of binding with high specificity to an antigen
The ABO blood group system was discovered by Austrian immunologist Karl Landsteiner in 1901
The ABO blood group antigens (agglutinogens) are attached to oligosaccharide chains that project above the RBC surface
The A and B antigens are inherited from both parents, dividing individuals into four major blood types
The A and B antigens are the most important of the more than 100 different blood group antigens identified
Two groups of antigens can cause transfusion reactions more than others: ABO and Rh systems of antigens
Agglutinins, the antibodies, are gamma globulins, with most being IgM and IgG immunoglobulin molecules
Agglutinins have two binding sites (IgG type) or 10 binding sites (IgM type), causing cells to clump together by the process of "agglutination"
High levels of agglutinins are found in the plasma of people who have never been exposed to a different type of blood, considered naturally occurring antibodies
Mismatched transfusions can lead to acute kidney failure due to the release of large amounts of hemoglobin from ruptured donor erythrocytes
The Rh blood group system has over 50 antigens, with D being the most antigenic component
The D antigen is the most immunogenic, making it most likely to cause a transfusion reaction in the recipient
85% of Caucasians are D-positive in the Rh system
In the A-B-O system, plasma agglutinins cause transfusion reactions spontaneously, while in the Rh system, spontaneous agglutinins almost never occur
For significant transfusion reactions to develop in the Rh system, a person must first be massively exposed to an Rh antigen, such as by transfusion of blood containing the Rh antigen
When red blood cells (RBCs) containing Rh factor are injected into an Rh-negative person, anti-Rh agglutinins develop slowly, reaching maximum concentration about 2 to 4 months later
With multiple exposures to the Rh factor, an Rh-negative person eventually becomes strongly "sensitized" to Rh factor, leading to enhanced and potentially severe transfusion reactions with subsequent transfusions of Rh-positive blood
Erythroblastosis fetalis, also known as "Hemolytic Disease of the Newborn," is characterized by agglutination and phagocytosis of the fetus’s red blood cells, particularly significant when an Rh-negative mother carries an Rh-positive fetus
In Erythroblastosis fetalis, maternal anti-Rh antibodies can cause agglutination of the fetus’s blood, leading to hemolysis, jaundice in the baby, and potential damage to other cells of the body