Blood Types

The Discovery of Blood Types

  • Before 1901, blood transfusions were risky because the reasoning behind why they worked or why they failed was unknown.
  • In Austria, Karl Landsteiner discovered human blood groups, which made blood transfusions safer.

Key Terms

  • Agglutination: Clumping of blood into a granular-looking substance.
  • Antigens: Special protein markers found on the surface of cells.
  • Antibodies: Special proteins that attack foreign antigens.

What Are Different Blood Groups?

  • Two systems determine blood type:
    • ABO Blood Grouping (Four types: A, B, AB, & O)
    • Rh Blood Grouping (+ or -)
  • Total of 8 different blood groups.
  • Determined by the presence or absence of certain proteins called antigens and antibodies.
  • Individuals have different types of blood, depending on what they inherited from their parents.

ABO Blood Grouping

  • Blood group A
    • A antigens on RBCs
    • B antibodies in plasma
  • Blood group B
    • B antigens on RBCs
    • A antibodies in plasma
  • Blood group AB
    • Both A and B antigens on RBCs
    • No A or B antibodies in plasma
  • Blood group O
    • No antigens on RBCs
    • Both A and B antibodies in plasma

The ABO Blood System

  • Blood Type (Genotype), Red Blood Cell Surface Proteins (Phenotype), Plasma Antibodies (Phenotype)
    • Type A (AA, AO): A agglutinogens only, b agglutinin only
    • Type B (BB, BO): B agglutinogens only, a agglutinin only
    • Type AB (AB): A and B agglutinogens, No agglutinin
    • Type 0 (00): No agglutinogens, a and b agglutinin

What Does this Mean for Blood Donation?

  • Type A blood donated to a Type A recipient results in no agglutination because the anti-B antibodies in the recipient do not combine with Type A antigens.
  • Type A blood donated to a Type B recipient causes an agglutination reaction because anti-A antibodies in the recipient combine with Type A antigens.

Blood Type Compatibility Chart

  • Blood Type: A
    • Antigen on Erythrocyte: A
    • Antibody in Plasma: anti-B
    • Donate to: A or AB
    • Receive from: A or O
  • Blood Type: B
    • Antigen on Erythrocyte: B
    • Antibody in Plasma: anti-A
    • Donate to: B or AB
    • Receive from: B or O
  • Blood Type: AB
    • Antigen on Erythrocyte: A & B
    • Antibody in Plasma: none
    • Donate to: AB
    • Receive from: A, B, AB, or O
  • Blood Type: O
    • Antigen on Erythrocyte: none
    • Antibody in Plasma: anti-A & anti-B
    • Donate to: A, B, AB, or O
    • Receive from: O

Rh Factor Blood Grouping

  • Rhesus Factor, first studied in Rhesus monkeys
  • Second way to express blood grouping
  • Combines with the ABO blood grouping system
  • People either have the antigen or they don’t
    • Rh+: the Rh antigen is present
    • Rh-: the Rh antigen is absent

Rh Factor and Agglutination

  • Rh factors can cause an agglutination reaction.
  • Difference between ABO and Rh groups:
    • ABO groups: bodies automatically have antibodies present
    • Rh grouping: bodies don’t automatically have antibodies
  • Person with Rh- blood can develop antibodies if they receive a blood transfusion from an Rh+ person

Hemolytic Disease of the Newborn

  • Biggest problem with Rh factor is mother-infant relationship.
  • If mother is Rh+ à no problem b/c she cannot develop antibodies

Hemolytic Disease of the Newborn: Rh- Mother

  • If the mother is Rh-:
    • Child is Rh+ while mother is Rh-.
    • Placenta prevents Rh+ from being exposed to mother.
    • During birth, Rh+ mixes with the mother’s immune system, causing antibodies against Rh factor to be produced.

Hemolytic Disease of the Newborn: Subsequent Pregnancies

  • Takes time to produce these antibodies, so first child is typically protected.
  • Future pregnancies with Rh+ fetuses may cause mom’s immune system to attack any Rh+ cells, even those of the fetus, causing the agglutination reaction

Hemolytic Disease of the Newborn: Prevention

  • If there’s a risk of Rh incompatibility, the mother will receive a series of shots that neutralize the mother immune system against the fetus

Summary of Blood Types

  • Here are the 8 different Blood Types
    • A+
      • A antigen
      • Rh factor
    • B+
      • B antigen
      • Rh factor
    • AB+
      • A & B antigen
      • Rh factor
    • O+
      • Rh factor
    • A-
      • A antigen
    • B-
      • B antigen
    • AB-
      • A & B antigen
    • O-

Blood Type Antigens and Antibodies

  • Type A blood: Red blood cells have type A surface antigens. Plasma has anti-B antibodies.
  • Type B blood: Red blood cells have type B surface antigens. Plasma has anti-A antibodies.
  • Type AB blood: Red blood cells have type A and type B surface antigens. Plasma has neither anti-A nor anti-B antibodies.
  • Type O blood: Red blood cells have neither type A nor type B surface antigens. Plasma has both anti-A and anti-B antibodies.