Presentation on theme: "Blood group and ABO antigens"— Presentation transcript:
1 Blood group and ABO antigens Lecturer Bahiya Osrah
2 History: Karl Landsteiner Discovered the ABO Blood Group System in 1901Blood types:Type A, Type B, Type AB, & Type OThe identification of blood group depends on the antigen and antibodies produced by the immune system.
3 IntroductionAntigens: chemical structures imparting specific properties to the surface of the RBCAntibodies: protein substance developed in response to foreign body substancesThree antigens we need to focus on: A, B, and H antigens that are usually expressed on the red blood cells surface.The presence or absence of the A, B, and H antigens is controlled by the H and ABO genes
4 ABO BasicsBlood group antigens are actually sugars attached to the red blood cell.Antigens are “built” onto the red cell.Individuals inherit a gene which codes for specific sugar(s) to be added to the red cell.The type of sugar added determines the blood group.
5 H AntigenThe H gene codes for an enzyme that adds the sugar fucose to the terminal sugar of a precursor substance (PS)The precursor substance (proteins and lipids) is formed on an oligosaccharide chain (the basic structure)
6 RBC Precursor Structure GlucoseGalactosePrecursor Substance (stays the same)N-acetylglucosamineGalactose
7 Formation of the H antigen RBCGlucoseH antigenGalactoseH enzyme is fucosyltransferaseN-acetylglucosamineGalactoseFucose
8 A and B AntigenThe “A” gene codes for an enzyme (transferase) that adds N-acetylgalactosamine to the terminal sugar of the H antigenN-acetylgalactosaminyltransferaseThe “B” gene codes for an enzyme that adds D- galactose to the terminal sugar of the H antigenD-galactosyltransferase
9 Formation of the A antigen RBCGlucoseGalactoseN-acetylglucosamineGalactoseN-acetylgalactosamineFucose
10 Formation of the B antigen RBCGlucoseGalactoseN-acetylglucosamineGalactoseGalactoseFucose
11 GeneticsThe H antigen is found on the RBC when you have the Hh or HH genotype, but NOT from the hh genotypeThe A antigen is found on the RBC when you have the Hh, HH, and A/A, A/O, or A/B genotypesThe B antigen is found on the RBC when you have the Hh, HH, and B/B, B/O, or A/B genotypes
12 ABO Type Frequencies In U.S. Per CentO45%A40%B11%AB4%
13 Landsteiner’s RuleIndividual’s will form immune antibodies to ABO blood group antigens they do not possess.Critical for understanding compatibility between ABO blood groups.
14 Antibody clinical significance Immunizations are frequently done to protect us from disease.Receive Hepatitis B immunization.Actual bits of hepatitis virus injected.Body recognizes as foreign and produces an immune antibody.Subsequent exposure to real Hepatitis B virus will result in destruction of the virus by immune antibodies.ABO antibodies are immune and will result in destroying incompatible cells which may result in the death of the recipient.
15 Genetics Two genes inherited, one from each parent. Individual who is A or B may be homozygous or heterozygous for the antigen.Heterozygous: AO or BOHomozygous: AA or BBPhenotype is the actual expression of the genotype, ie, group AGenotype are the actual inherited genes which can only be determined by family studies, ie, AO.
16 Group O Has NO antigens on RBC surface Approximately 45% of the population is group O.Has NO antigens on RBC surfaceHas anti-A & anti-B antibodies in the plasmaUniversal Donor: can be given to any blood type no antigens on the RBCsGenotype OO = Phenotype O
17 Group A Approximately 40% of the population is group A. No B antigens present.Has A antigens on the RBC surfaceHas anti-B antibodies in the plasmaGenotypes AA & AO = Phenotype A
18 Group B Approximately 11% of the population is group B. No A antigens present.Has B antigens on the RBC surfaceHas anti-A antibodies in the plasmaGenotype BB & BO = Phenotype B
19 Group AB Approximately 4% of the population is group AB. Has A & B antigens on the RBC surfaceHas NO antibodies in the plasmaUniversal Recipient: can receive Type A, Type B, Type AB, or Type O blood NO antibodies in plasma to react with antigensGenotypes: AB = Phenotype ABNOTE: This slide is in error as it only illustrates presence of one antigen not 2.
20 HemolysisIf 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.
21 Summary A Anti-B A or O B Anti-A B or O AB A and B none AB, A, B or O Blood GroupAntigens on cellAntibodies in plasmaTransfuse with groupAAnti-BA or OBAnti-AB or OABA and BnoneAB, A, B or OONoneAnti-A & B
22 Rh (D) AntigenRh refers to the presence or absence of the D antigen on the red blood cell.Discovered by Landsteiner & Wiener in 1937Discovered in the Rhesus monkeyRh is an antigen on the RBC surfaceRh + has the antigens on the RBC (85% of population)Rh – does NOT have the Rh antigensRh + can accept Rh + or Rh – bloodRh – can accept ONLY Rh - blood
23 Rh (D) AntigenProduction 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.Because the Rh(D) positive individuals already have D antigen and that will trigger the immune response of the negative individuals to the D-antigens and that will cause death
24 Erythroblastosis fetalis Rh– mother and Rh+ father Rh+ child 1st pregnancyduring pregnancy fetal Rh pos rbc’s escape into maternal circulation (antigents)Mother develops antibodies to baby’s Rh+ antigens2nd pregnancy with Rh+ child mother’s anti-Rh antibodies attack unborn child’s RBCsPrevention: shot of Rhogam shortly after birth of first Rh+ baby to block development of antibodiesAntigen-antibody reaction due to mixing of Rh+ blood of fetus with Rh- blood of mother during 2nd Rh+ pregnancy
25 Blood Typing There are 2 components to blood typing: Test unknown cells with known antibodiesTest unknown serum/plasma with known rbc’sThe patterns are compared and the blood group is determined.
26 Slide Blood Typing - continued 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
27 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.
28 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.
29 Slide Blood Typing Group A An unknown rbc suspension is added to known anti-sera.The left hand of the slide contains anti-A which reacts with the unknown cell.The right hand side contains anti-B which does not react with the cell.
30 Slide Blood Typing Group B An unknown rbc suspension is added to known anti-sera.The left hand of the slide contains anti-A does not react with the unknown cell.The right hand side contains anti-B which reacts with the cell.
31 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.
32 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.
33 Summary of Slide Typing Anti-AAnti-BBlood GroupNEGOPOSABAB
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