Biology II: Human Blood Groups

• MED-109 Biology II, Lab practical 1 focuses on the topic of human blood groups.

Learning Objectives

• To distinguish between antigens and antibodies.
• Aim to explain the differences between human blood types.
• Need to understand the procedure of the haemagglutination inhibition test.
• Expected to explain blood type choice during transfusions.
• Required to explain the inheritance pattern of blood type alleles based on lecture and practical knowledge.

Assessment Details

• A lab report on human blood groups is required.
• Lab guidelines template is released on Moodle on Thursday February 20th, containing questions and marking guidelines.
• The lab report release date is Thursday, February 20th (afternoon). -A student template (answer version), where answers should be provided, will also be released on Moodle on Thursday, February 20th.
• It must be submitted online via Turnitin.
• The lab report submission deadline is Friday, February 28th at 5 pm.
• Students are advised not to copy text from the lab guidelines to avoid high similarity scores in Turnitin.
• Submit only the student template document (answer version) and not the guideline document.

Phenotype and Genotype of Blood Groups

• Four blood groups exist: A, B, AB, and O.
• These blood groups result from combinations of 3 different alleles of 1 gene, symbolized as A, B, and O (or IA, IB, and i).
• Each person carries two alleles, leading to 6 possible genotypes: AA, AO, BB, BO, AB, and OO.
• The A and B alleles are co-dominant, and both are dominant over the recessive O allele.

Blood Group Characteristics

• Blood group A has either genotype AA or AO.
• Blood group B has either genotype BB or BO.
• Blood group AB has genotype AB.
• Blood group O has genotype OO.

Antigens and Antibodies

• An antigen is a molecule capable of inducing an immune response, such as antibody production, in the host organism.
• Antigens are usually present on the surface of cells, bacteria, viruses etc.
• The immune system responds to foreign invaders by producing specific antibodies against foreign antigens.

Blood Transfusions: Antigens and Antibodies

• Blood group A has antigen A and produces antibodies against antigen B.
• Blood group B has antigen B and produces antibodies against antigen A.
• Blood group AB has antigens A and B and produces no antibodies.
• Blood group O has no antigens and produces antibodies against antigens A and B.

Blood Group Compatibility

• Blood serum must not carry antibodies against a donor's antigens, or haemagglutination will occur.
• For example, if a person with blood type A receives blood from a person with blood type B, the anti-B antibodies in the recipient's blood will attack the B antigens on the donor's red blood cells leading to lysis of the RBC.

Haemagglutination Method

• This method is used to determine blood type by observing the reaction when blood is mixed with added antibodies.

The Rhesus (Rh) Factor

• The Rh (Rhesus) factor, also known as the D antigen, is a prominent antigen that may be present on red blood cells.
• The Rh factor is determined by two alleles (Rh+/rh- or D/d), with Rh+ being dominant and rh- recessive.
• Rh positive individuals have the Rh antigen on their red blood cells.
• Rh negative individuals do not have the Rh antigen on their red blood cells.
• Rh negative individuals cannot receive blood from Rh positive individuals.
• Rh positive individuals can receive blood from both Rh negative and positive individuals.

Rhesus Factor Inheritance

• Autosomal dominant pattern: Rh+ is the D allele (dominant), and rh- is the d allele (recessive).

Blood Transfusion Compatibility

• O+ has Rh antigens and anti-A and anti-B serum antibodies.
• O- has no antigens, but it has anti-A and anti-B serum antibodies.
• A+ has A and Rh antigens, and anti-B serum antibodies.
• A- has A antigens and anti-B serum antibodies.
• B+ has B and Rh antigens, and anti-A serum antibodies.
• B- has B antigens and anti-A serum antibodies.
• AB+ has A, B, and Rh antigens and no serum antibodies.
• AB- has A and B antigens and no serum antibodies.
• Anti-Rh antibodies are only produced in the blood of Rh- people.

The Rhesus Factor and Pregnancy

• Haemolytic disease of the newborn (HDN) can occur if an Rh- mother is pregnant with an Rh+ child.
• During pregnancy or labor, fetal red blood cells may cross into the mother's bloodstream, causing her to produce anti-Rhesus antibodies.
• In subsequent pregnancies, these antibodies can cross the placenta and attack the Rh+ fetus, leading to fetal haemolysis and stillbirth.

Prevention of Fetal Haemolysis

• Injection of the mother with anti-Rhesus antibodies (RhoGAM) after the birth of the first Rh+ child.

Blood Transfusions

• AB+ is the universal recipient.
• O- is the universal donor.
• Blood group typing experiment is demonstrated via a youtube link.

Procedure for Determining blood groups

• Obtain 3 glass slides and label them with anti-A, anti-B and anti-D.
• Soak a piece of cotton wool in rubbing alcohol and disinfect your finger.
• Use a sterilized lancet to prick your finger and place a drop of blood to on each slide.
• Add 1 drop of anti-A, anti-B and anti-D serums to the appropriate slides and mix with separate toothpicks.
• Allow 1-2 minutes for agglutination to occur
• Observe samples macroscopically and microscopically using your lense to determine blood group and fill in data on lab report.

This lesson covers human blood groups, antigens, and antibodies. It explains the differences between blood types and the haemagglutination inhibition test. It also looks at blood type choices during transfusions and the inheritance pattern of blood type alleles.