Lecture 3 blood bank THE ABO BLOOD GROUP SYSTEM By Dr. Dalia Galal Hamouda

Importance of the ABO system Blood Group System is most important in blood transfusion ABO Antibodies Natural antibodies  found in the serum of people who lack the antigen and antigenic stimulus is environmental  exposure occurs from birth Newborns  without ABO antibodies of their own; begin to produce Ab with detectable titer at 6 months of age Other characteristics of ABO antibodies: 1.IgM 2.Reacts at room temp. after an immediate spin 3.If ABO antibodies react with antigens in vivo, result is acute hemolysis and possibly death

The "A“ and "B" antigens are also produced by some other plants and microorganisms. Thus, individuals who do not recognize one or more of these antigens as "self" will produce antibodies against the plant or microbial antigens. Why do individuals produce antibodies to antigens they do not have?

ABO grouping is required for all of the following individuals: Blood Donors-since it can be life threatening to give the wrong ABO group to the patient. Transfusion recipients-since we need to know the donor blood is ABO compatible. Transplant Candidates and Donors-ABO antigens are found in other tissues as well. Therefore the transplant candidates and donors must be compatible. Prenatal Patients-To determine whether the mothers may have babies who are suffering from ABO-HDN. It is also beneficial to know the ABO group should she start hemorrhaging. Newborns (sometimes) If the baby is demonstrating symptoms of Hemolytic Disease of the Newborn, the ABO group needs to be determined along with Rh and others. Paternity testing Since the inheritance of the ABO Blood Group System is very specific, this determines that the accused father is the father or not

According to the ABO blood typing system there are four different kinds of blood types: A, B, AB or O (null). ABO blood grouping system

Blood group A If you belong to the blood group A, you have A antigens on the surface of your RBCs and B antibodies (anti-B) in your blood plasma. Blood group B If you belong to the blood group B, you have B antigens on the surface of your RBCs and A antibodies (anti-A) in your blood plasma. AB0 blood grouping system

Blood Groups, Blood Typing and Blood Transfusions The discovery of blood groups Experiments with blood transfusions, the transfer of blood or blood components into a person's blood stream, have been carried out for hundreds of years. Many patients have died and it was not until 1901, when the Austrian Karl Landsteiner discovered human blood groups, that blood transfusions became safer. Mixing blood from two individuals can lead to blood clumping or agglutination. The clumped red cells can crack and cause toxic reactions. This can have fatal consequences. Karl Landsteiner discovered that blood clumping was an immunological reaction which occurs when the receiver of a blood transfusion has antibodies against the donor blood cells. Karl Landsteiner's work made it possible to determine blood types and thus paved the way for blood transfusions to be carried out safely. For this discovery he was awarded the Nobel Prize in Physiology or Medicine in What is blood made up of? An adult human has about 4–6 liters of blood circulating in the body. Among other things, blood transports oxygen to various parts of the body. Blood consists of several types of cells floating around in a fluid called plasma. The red blood cells contain hemoglobin, a protein that binds oxygen. Red blood cells transport oxygen to, and remove carbon dioxide from, the body tissues. The white blood cells fight infection. The platelets help the blood to clot, if you get a wound for example. The plasma contains salts and various kinds of proteins. What are the different blood groups? The differences in human blood are due to the presence or absence of certain protein molecules called antigens and antibodies. The antigens are located on the surface of the red blood cells and the antibodies are in the blood plasma. Individuals have different types and combinations of these molecules. The blood group you belong to depends on what you have inherited from your parents. There are more than 20 genetically determined blood group systems known today, but the AB0 and Rh systems are the most important ones used for blood transfusions. Not all blood groups are compatible with each other. Mixing incompatible blood groups leads to blood clumping or agglutination, which is dangerous or individuals. Nobel Laureate Karl Landsteiner was involved in the discovery of both the AB0 and Rh blood groups. AB0 blood grouping system Blood group AB If you belong to the blood group AB, you have both A and B antigens on the surface of your RBCs and no A or B antibodies at all in your blood plasma. Blood group O If you belong to the blood group O (null), you have neither A or B antigens on the surface of your RBCs but you have both A and B antibodies in your blood plasma.

The ABO gene is autosomal (the gene is not on either sex chromosomes) The ABO gene locus is located on the chromosome 9. Each person has two copies of genes coding for their ABO blood group (one maternal and one paternal in origin) A and B blood groups are dominant over the O blood group A and B group genes are co-dominant ABO inheritance and genetics

AUTOSOMAL CHROMOSOME Mustafa Sara one alleles from Mustafa and one from Sara. The alleles for Blood group are in the same place on the chromosome 9. However the genes have a different code giving the different blood group AB

This meant that if a person inherited one A group gene and one B group gene their red cells would possess both the A and B blood group antigens. These alleles were termed A ( which produced the A antigen ), B (which produced the B antigen) and O (which was "non functional"and produced no A or B antigen) What do co-dominant genes mean?

ABO BLOOD GROUP SYSTEM Phenotype (blood group) Antigen on RBCs Natural antibody Genotype AA onlyAnti-BAA or AO BB onlyAnti-ABB or BO ABA and BNoneAB ONoneAnti-A, Anti-B OO The table shows the four ABO phenotypes ("blood groups") present in the human population and the genotypes that give rise to them.

ABO BLOOD GROUP SYSTEM Example of determining offspring blood types from known or suspected genotypes: Genotype parent #1 (AO) AO Genotype parentA AA AO #2 (AB)B AB BO Phenotypes of possible offsprings: A, AB, B

Parent Allele ABO AAAABAO BABBBBO OAOBOOO Possible Blood group Genotypes

Antiserum An antiserum is a purified, diluted and standardized solution containing known antibody, which is used to know the presence or absence of antigen on cells. Antiserum is named on the basis of the antibody it contains: - Anti- A antiserum which contains anti- A antibody - Anti- B antiserum which contains anti- B antibody - Anti- AB antiserum, which contain both anti A and B antibodies. - Anti –D antiserum which contains anti- D antibody Sources of antisera - Animal inoculation in which animals are inoculated by known antigen and the resulting serum containing known antibody is standardized for use as antiserum. - Serum is collected from an individual who has been synthesized to the antigen through transfusion, pregnancy or injection.

Manifestation and Interpretation of Antigen- Antibody reactions The reactions (resulting from the combination of a red cell antigen with its corresponding antibody) are agglutination and/ or haemolysis. Hemolysis: is the break down or rupture of the red cell membrane by specific antibody (hemolysin) through the activation of complement with the release of hemoglobin and produce red color. Agglutination: is the clumping of red cells when antigens on the red cell membrane bind with their specific antibodies.it is the widely observed phenomenon in blood grouping. The agglutination of the red cells are called hemagglutination The antigen is called agglutinogen The antibody is called agglutinin.

Hemagglutination of red cells takes place in two stages: First Stage: red cell sensitization (when red cell become coated by antibodies) Ag and Ab held by non-covalent interactions Second Stage: The physical agglutination or clumping of the sensitized red cells (antibody attaches to antigen on more than one red cell) formation of stable latticework  basis of visible reaction