Blood Groups Part I (ABO & Rh) PDF

Faculty of Applied Health Science Technology Medical Laboratory Technology Department Blood Banking HLBB-401 Blood Group systems (part-I) By Dr. Hadeel Said Tawfik  ILOS Identify different blood group systems. Describe ABO blood grou...

Faculty of Applied Health Science Technology Medical Laboratory Technology Department Blood Banking HLBB-401 Blood Group systems (part-I) By Dr. Hadeel Said Tawfik  ILOS Identify different blood group systems. Describe ABO blood group system. Mention the inheritance of ABO blood group system. Identify the blood typing tests. Describe the Rh system. Mention the importance of blood group systems.  Blood group systems There are thirty five current human blood group systems. ABO blood group system Rh blood group system The ABO blood group system is the most important blood group system in human blood transfusion then the Rh system.  Definition Blood groups system consists of antigens on RBCs This antigenic pattern is consistent throughout life and identified by specific Abs.  History Austrian Karl Landsteiner discovered the ABO Blood Group System in 1901. Nobel Prize in Physiology and Medicine in 1930.  LANDSTEINER’s LAW- 1.If an antigen is present on red blood cell membrane ,the corresponding antibody must be absent in the plasma. 2.If an antigen is absent on red blood cell membrane, then corresponding antibody must be present in the plasma. The ABO System  The ABO System 4 Main Phenotypes (A, B, AB, O) ABO gene located on long arm of chromosome 9 ABO & Rh(D) 8  ABO Basics Blood group antigens are actually sugars attached to the red blood cell. The type of sugar added determines the blood group.  The ABO Antigens A antigen is N-acetyl-galactosamine (GalNAc) B antigen is Galactose (Gal) ABO & Rh(D) 10  The ABO Antigens Appear in the sixth week of fetal life. H antigen is also present usually in all individuals. RBC Precursor Structure RBC Glucose Galactose Precursor Substance (stays the N-acetylglucosamine same) Galactose Formation of the H antigen RBC Glucose H antigen Galactose N-acetylglucosamine Galactose Fucose  H antigen The H antigen is the foundation upon which A and B antigens are built A and B genes code for enzymes that add an immunodominant sugar to the H antigen – Immunodominant sugars are present at the terminal ends of the chains and confer the ABO antigen specificity  A and B Antigen The “A” gene codes for an enzyme (transferase) that adds N-acetylgalactosamine to the terminal sugar of the H antigen – N-acetylgalactosaminyl transferase The “B” gene codes for an enzyme that adds D-galactose to the terminal sugar of the H antigen – D-galactosyltransferase Formation of the A antigen RBC Glucose Galactose N-acetylglucosamine Galactose N-acetylgalactosamine Fucose Formation of the B antigen RBC Glucose Galactose N-acetylglucosamine Galactose Fucose Galactose Group O individuals have no A or B genes to convert the H antigen to A or B antigens ….that means H antigen sites are maintained.  A A A A Group O Group A Many H Fewer H A antigen sites antigen sites Most of the H antigen sites in a Group A individual have been converted to the A antigen  ABO Antibodies A and B substances very common Antibodies produced to “non-self” A & B people have mainly IgM O people have IgG 21  Group A A antigens present No B antigens present. These individuals form potent anti-B antibodies which circulate in the blood plasma at all times.  Group B B antigens present No A antigens present. These individuals form potent anti-A antibodies which circulate in the blood plasma at all times.  Group AB Both A and B antigens present. These individuals possess no A and B antibodies.  Group O No A or B antigens present. Anti-A and anti-B antibodies circulate in the blood plasma at all times.  Inheritance of ABO blood group Two genes inherited, one from each parent. Individual who is A or B may be homozygous or heterozygous for the antigen. Heterozygous: AO or BO Homozygous: AA or BB Phenotype is the actual expression of the genotype, ie, group A Genotype are the actual inherited genes which can only be determined by family studies, ie, AO. Inheritance of ABO blood group Follows Mendelian Law. Heterozygous: AO or BO Homozygous: AA or BB Blood Typing  Slide Blood Typing The slide is divided into halves. On one side a drop of anti-A is added, this will attach to and cause clumping of RBCs possessing the A antigen. On the other side a drop of anti-B is added which will cause clumping of RBCs with the B antigen. A drop of RBCs is added to each side and mixed well with the reagent. The slide is tilted back and forth for one minute and observed for agglutination (clumping) of the RBCs  Interpretation of Slide Typing Testing with Anti-A Anti-Serum If an RBC contains the A antigen the red blood cells will be agglutinated by anti-A, a positive reaction. If an RBC does not have the A antigen there will be no clumping, a negative reaction.  Interpretation of Slide Typing Testing with Anti-B Anti-Serum If an RBC contains the B antigen the red blood cells will be agglutinated by anti-B, a positive reaction. If an RBC does not have the B antigen there will be no clumping by anti-B, a negative reaction.  Slide Blood Typing Group AB The left hand of the slide contains anti-A which reacts with the unknown cell. The right hand side contains anti-B which reacts with the unknown cell.  Slide Blood Typing Group O The left hand of the slide contains anti-A does not react with the unknown cell. The right hand side contains anti-B does not react with the unknown cell.  Summary of Slide Typing Anti-A Anti-B Blood Group NEG NEG O POS NEG A NEG POS B POS POS AB  Significance of ABO Group ABO mismatched transfusions If an individual is transfused with an incompatible blood group destruction of the red blood cells will occur. This may result in the death of the recipient.  Universal Donor and Recipient Universal Donor Universal Recipient Group O Group AB – Carries no A or B –Patient has no antigens anti-A or anti-B – Packed and present processed units –Cannot lyse any have little antibody transfused cells 41  Summary Blood Antigens on Antibodies Transfuse with Group cell in plasma group A A Anti-B A or O B B Anti-A B or O AB A and B none AB, A, B or O O None Anti-A & O B  Subgroups of A (A1 and A2) Different levels of expression of A on RBCs are classified into: subgroups –80% of group A individuals are A1 –20% are A2  Difference Between A1 and A2 A1 has more A and less H antigen on the cell. A2 has less A and more H antigen Subgroups of A Rh SYSTEM The Rh(D) Antigen RH is the most complex system Discovered in 1940 after work on Rhesus monkeys RH gene located on short arm of chromosome 1 47  Rh (D) Antigen Rh is a blood group system with many antigens, one of which is D. Rh refers to the presence or absence of the D antigen on the red blood cell.  Rh (D) Antigen Production of antibody to D requires exposure to the antigen. The D antigen is very immunogenic, ie, individuals exposed to it will very likely make an antibody to it. For this reason all individuals are typed for D, if negative must receive Rh (D) negative blood.  Rh (D) Antigen The most important patient population to consider is females of child-bearing age. If immunized to Rh (D) antigen the antibody can cross the placenta and destroy Rh (D) positive fetal cells resulting in death. This is why Rh negative women are given Rhogam after birth of Rh positive baby.  Significance of Rh(D) Rh(D) negative persons exposed to Rh(D) positive blood will develop anti-D Anti-D can also be stimulated by pregnancy with an Rh(D) positive baby – Sensitisation can be prevented by the use of anti- D immunoglobulin, antenatally and post natally Rh(D) negative females of childbearing potential should never be given Rh(D) positive blood products 51 Hemolytic Disease of the Neborn – How it Occurs 1- child is Rh positive. 2- During pregnancy fetal Rh positive RBC’s escape into maternal circulation 3- Mother produces antibodies to Rh (D) antigen 4- Second pregnancy with Rh (D) positive child results in destruction of fetal D positive RBCs  Training questions Mention two blood group systems? Describe ABO system? Mention the importance of Rh system? THANK YOU