Blood Grouping and Transfusion Notes

Class Overview

• Introduction to blood products.
• Risks associated with blood products.
• Blood grouping: ABO and Rhesus (Rh) systems.
• Compatibility testing.
• Reference: HaaG – Chapter 48-49.

Class Learning Objectives

• Describe available blood products and their applications.
• Compare and contrast the ABO and Rhesus blood groups.
• Explain blood typing and compatibility testing processes.
• Identify safe blood group transfusions for different ABO and Rhesus types.

Introduction to Blood Transfusion

• Blood transfusions treat life-threatening disorders.
• In Australia:
  • 80% of the population will receive a blood product during their lifetime.
  • 3% of the eligible population donate blood.

Blood Products

• Cellular:
  • Red cells
  • Platelets
  • White blood cells
• Non-cellular:
  • Plasma
  • Other components

Blood Products - Details

• Red Blood Cells:
  • Obtained by removing most plasma (centrifugation) and leucocytes (filter).
  • Volume > 240 ml.
  • Shelf life:
    • Fresh: < 5 days.
    • ‘Packed’ (in sodium chloride, adenine, glucose, mannitol): 42 days @ 2-6°C.
  • Applications:
    • Hemorrhage (bleeding).
    • Severe anemia refractory to other treatments.
    • Urgent cases (hypoxia).
• Platelets:
  • Obtained by centrifugation.
  • Volume: 200-240 ml (~ 2.4 \times 10^{11} platelets).
  • Pooled from 4-5 donors.
  • Shelf life: 4-6 days.
  • Applications:
    • Thrombocytopenia.
    • Platelet function defects.
    • Prior to surgery, especially after trauma/previous surgery.
• Plasma:
  • Fresh frozen: obtained by centrifugation and frozen within 18 hours of collection.
  • Contains all coagulation factors.
  • Shelf life: within 24 hours of thawing if kept @ 2-6°C.
  • Applications:
    • Coagulation factor deficiencies.
• Other Blood Products:
  • Specific elements are obtained from pooled plasma by biochemical fractionation and sterilization.
  • Cryoprecipitate:
    • Obtained from fresh frozen plasma by controlled thawing.
    • Rich in fibrinogen + Factor VIII + vWF.
    • Used for coagulation factor deficiencies.
  • Albumin Solution:
    • Obtained from pooled plasma that is heat-treated at low pH followed by precipitation/ultra-filtration.
    • ~98% pure albumin.
    • Contributes to osmotic pressure.
    • Used for loss of blood volume.
  • Immunoglobulin (Ig):
    • Obtained from plasma by fractionation.
    • Used for immune disorders (normal ‘standard’ Ig) and specific infections (e.g., hepatitis A, measles) (convalescent Ig).

Risks of Blood Products

• Like any biologically-derived treatment, there are risks to the use of blood products, especially those produced from pooled plasma.
• All efforts are made to reduce these risks.
• Infection:
  • Viral
  • Bacterial
  • Other
  • Screening (fresh).
  • Inactivation (heat, pasteurization, etc.) for blood products.
• Mechanical damage:
  • Volume overload
  • Air embolus
  • Care in administration.
• Immune reactions:
  • Against blood product:
    • Acute hemolytic reactions (RBCs).
    • White cell and platelet reactions.
    • Anaphylaxis.
  • Against recipient (plasma, immunoglobulin, white cells):
    • Graft versus host disease.
    • Fever, chills, breathing difficulties, kidney damage, stroke, fatality.
    • Blood matching.

Blood Grouping

• The major issue regarding blood transfusion is an antibody reaction against antigens on the incoming red blood cells.
• Over 200 different antigens identified.
• Most important:
  • ABO
  • Rhesus (Rh)

ABO Blood Groups

• Identified in 1901 by Karl Landsteiner.
• Human blood classified into types:
  • A (40%)
  • B (8%)
  • AB (3%)
  • O (45%)
• Correspond to alternate surface antigens.
• ABO antigens are not direct gene products, but sugars.
• A and B are alleles of a glycosyltransferase gene that add alternate sugars to a non-immunogenic precursor (H antigen):
  • A = adds N-acetylgalactosamine (N-Ac-Gal).
  • B = adds galactose (Gal).
• This produces A and B antigens that are highly immunogenic.
• Blood groups correspond to specific genotypes:
  • O/O = no A or B allele = H antigen = Group O.
  • A/A or A/O = A allele = A antigen = Group A.
  • B/B or B/O = B allele = B antigen = Group B.
  • A/B = A allele + B allele = A+B antigen = Group AB.
• The absence of an antigen means antibodies are able to develop against it (i.e., no self-tolerance):
  • Group O = anti-A + anti-B antibodies.
  • Group A = anti-B antibodies.
  • Group B = anti-A antibodies.
  • Group AB = no antibodies.

ABO Compatibility – Blood Cells

• Recipients can only receive blood cells from a donor with antigens compatible with the antibodies of the recipient.


• Compatibility Table:
  

• Certain products (e.g., plasma) contain antibodies that can instead react with the blood cells of the recipient.


• Compatibility reversed.


• Compatibility Table:
  

• Binary grouping:
  • Rh+ individual:
    • Rh antigen on cells.
    • No anti-Rh antibodies.
    • Can receive red cells from Rh+ or Rh-.
    • Should only receive plasma from Rh+.
  • Rh- individual:
    • No Rh antigen on cells.
    • Can develop anti-Rh antibodies.
    • Should only receive red cells from Rh-.
    • Can receive plasma from Rh+ or Rh-.

Rh Compatibility

• Blood Cells:
  

• Check blood groups in recipient and donor.
• Identify antibodies in the serum of recipient.
• Crossmatch – recipient serum vs donor red cells.
• Most common test is indirect anti-globulin test (IAT).
• Detects antibodies in a patient with potential to cause transfusion reaction.

Indirect Anti-globulin Test (IAT)

• Used for antibody screening and cross-matching:
  • Mix serum with red cells and incubate.
  • Wash and add anti-IgG.
  • Look for haemagglutination (e.g., tiles, tubes).
  • Antibody screen: uses reagent cells (known grouping).
  • Cross-match: uses recipient cells (unknown grouping).

Haemagglutination Techniques

• Tiles:
  • Large flat plastic tile partitioned into small squares.
  • Requires ~15-20% v/v RBC suspension.
  • RBCs settle forming a layer.
  • After tilting tile, either haemagglutination or free RBCs can be observed.
• Tubes:
  • Requires ~3-5% v/v RBC suspension.
  • Tubes centrifuged, agitated, and observed.
  • Rapid and efficient.
• Grading:
  • +++
  • +/-
  • -

Blood Group Distribution in Australia

• Significant differences in the frequency of blood groups between Non-Indigenous and Indigenous populations.


• Blood banks need to consider these differences.


• Distribution Table: