Human Blood Groups Quiz

Blood Physiology: Blood Group Systems

• Blood is a common attribute of all people, composed of red blood cells, white blood cells, platelets, and plasma.
• Blood functions similarly in all individuals, but genetically linked variations in structure exist.
• Blood classification is based on proteins present (or absent) on red blood cell membranes.
• Common blood groups are ABO and Rhesus systems.

Learning Objectives

• Classify blood groups
• State the clinical significance of blood groups

Introduction

• All people have blood.
• Blood is made up of the same basic components (red blood cells, white blood cells, platelets, and plasma) in all people.
• Blood function is the same in all people but with genetically linked variations in structure.
• Blood types are determined by the presence or absence of proteins on red blood cell membranes.
• Common blood types are ABO and Rhesus.

Red Cell Membrane Proteins

• The diagram on slide 4 illustrates red cell membrane proteins. Specific proteins include Cromer, Knops, Diego, ABO, Band 3, Gerbich, Kell, Rh, Yt, LW, MNS, Lutheran, Duffy, and Indian.

Blood Group Categories

• Blood groups are categorized based on antigens on red blood cell membranes.
• Clinically common blood groups include ABO (A, B, AB, O) and Rhesus (Rh+ or Rh-).
• Eight common blood types exist (A+, A-, B+, B-, AB+, AB-, O+, O-).

ABO Blood Group System

• Discovered by Karl Landsteiner in 1901.
• ABO blood groups are determined by antigens (agglutinogens) on red blood cell membranes.
• Common types include A, B, AB, and O.

Nature of ABO Antigens

• H substance: precursor oligosaccharide on the red blood cell membrane, forming the basis for A and B antigens.
• A antigen forms by adding N-acetylgalactosamine to the H substance.
• B antigen forms by adding galactose to the H substance.
• Genes for A and B phenotypes are located on chromosome 9p.
• Gene products are glycosyl transferases. These enzymes attach specific antigenic carbohydrates.

H substance, A & B Antigen

• A diagram (slide 8) illustrates the structure of the H substance, A antigen, and B antigen. These consist of sugars and linkages.

ABO Blood Group Importance

• Individuals create natural antibodies to the ABO carbohydrate they lack.
• These antibodies are called isoagglutinins.
• An individual's serum contains antibodies that are non-complementary to their red blood cell antigens.
• Example: Type A individuals have anti-B antibodies, while Type B individuals have anti-A antibodies.

ABO Blood Groups

• (Table on slide 10) showing the antigens and antibodies present in each blood group.

Blood Group A

• Individuals with blood group A have A antigens on their red blood cells.
• Their serum contains anti-B antibodies.
• Can donate to A and AB.
• Can receive from A and O.

Blood Group B

• Individuals with blood group B have B antigens on their red blood cells.
• Their serum contains anti-A antibodies.
• Can donate to B and AB.
• Can receive from B and O.

Blood Group O

• Individuals with blood group O lack A and B antigens on their red blood cells.
• Their serum contains anti-A and anti-B antibodies.
• Can donate to all ABO blood types (A, B, AB, and O).
• Can receive only from O.

Blood Group AB

• Individuals with blood group AB have both A and B antigens on their red blood cells.
• Their serum does not contain anti-A or anti-B antibodies.
• Can receive from all ABO blood types (A, B, AB, and O).
• Can donate only to AB.

Bombay Blood Group

• Rare blood group, first discovered in Bombay (now Mumbai).
• Individuals lack the H gene and thus cannot produce H substance, the backbone for A and B antigens.
• Serum contains anti-A, anti-B, and anti-H.
• Individuals are phenotypically O.
• Agglutination occurs during crossmatching due to anti-H agglutinating O cells.

Rhesus Blood Group System

• Rhesus antigen (Rh factor) is located on red blood cell membranes.
• Discovered in 1937.
• Type D antigen is the most important and prevalent.
• Inherited on chromosome 1.
• Rh+ individuals have the D antigen.
• Rh- individuals lack the D antigen.
• Anti-Rh antibodies (anti-D) are not normally present in Rh- individuals unless stimulated by transfusion or an incompatible fetus.

Rhesus Factor and its Clinical Application

• Rh-positive individuals can receive Rh-positive or Rh-negative blood.
• Rh-negative individuals who receive Rh+ blood may not initially react, but they can become sensitized. Subsequent Rh+ blood transfusions can cause severe reactions.
• Rh incompatibility can occur in pregnancies where the mother is Rh- and the fetus is Rh+. This can lead to hemolytic disease of the newborn.

Anti-D Immunoglobulin

• Immunoglobulin injection (e.g., RhoGAM) is used to prevent Rh incompatibility in mothers.
• This injection is given during pregnancy and after delivery in cases of Rh-negative mothers and Rh-positive fetuses.

Racial Distribution of Blood Groups

• Racial differences in blood group frequencies exist.
• Slide 20 displays a table with racial data.

ABO Blood Group & Blood Transfusion

• Donors provide blood; recipients receive it.
• Compatibility assessment considers donor antigen and recipient antibody.
• Crossmatching involves matching donor and recipient plasma and red blood cells.
• Incompatibility can cause reactions like agglutination and red blood cell lysis. This can lead to severe reactions.

ABO Blood Grouping/Typing

• Indications include blood donors, transfusion recipients, transplant candidates, newborns, and paternity testing.

Landsteiner's Rule

• A person does not have an antibody to his/her own antigen.
• A person has naturally occurring antibodies to antigens they lack.
• These rules are characteristic of the ABO system, but not generally applicable to the Rh system.

ABO Typing

• ABO typing involves antigen typing and antibody detection.
• Forward typing identifies antigens on red blood cells.
• Reverse typing detects antibodies in the serum.

Forward Typing

• Determines antigens present on a person's red blood cells.
• Uses antisera (A and B) to find A and B antigens.
• Antisera are generated by exposing humans to A and B antigens, thereby stimulating antibody production.

Forward Typing Procedure

• A and B antisera are placed on a slide.
• Red blood cells are added to each antiserum.
• Observe for clumping (agglutination)

Results

• Agglutination with only antiserum A indicates blood type A.
• Agglutination with only antiserum B indicates blood type B.
• Agglutination with both antisera A and B indicates blood type AB.
• No agglutination indicates blood type O.

Reactions with Antisera Reagents

• (Table on slide 28) summarizes reactions with A and B antisera.

Reverse Typing

• Detects antibodies present in the serum.
• Uses A and B cells to identify antibodies.

Discrepancies in ABO Typing

• When forward and reverse typing results don't agree, further investigation is needed to determine the cause of the discrepancy.
• Inconsistencies are documented as "unknown" and are usually classified as group 0 when not resolvable.
• For transfusion, cross-matching is done to ensure safety.

Concept of Universal Donor and Recipient

• O-negative is the universal donor.
• AB-positive is the universal recipient.

ABO Inheritance Patterns

• A and B genes are found on chromosome 9.
• Each person inherits one allele from each parent.
• A and B alleles are codominant.
• O allele is recessive.

Homozygosity/Heterozygosity & ABO Inheritance

• Homozygous: having two identical alleles (e.g. AA, BB, OO).
• Heterozygous: having two different alleles (e.g., AO, BO).

ABO Phenotypes and Genotypes

• Phenotype: observable traits (e.g., blood type).
• Genotype: combination of alleles (e.g. AA, AO).

AO Mother & BO Father (and various other examples)

• (Tables on slides 35-40) illustrate possible blood group genotypes resulting from different parental combinations.

Further Reading

• A list of websites for further research into the topic of blood groups.

Test your knowledge on human blood groups and transfusion compatibility. This quiz covers topics such as blood group antibodies, the Bombay blood group, and Rh factor implications. Evaluate your understanding of these critical concepts in human biology!