Blood Typing Notes (Bio 11 Unit 3)

What Is Blood Typing?

• Blood typing is the classification of human blood based on the presence or absence of specific antigens on the surface of red blood cells (RBCs) and antibodies in plasma.
• Blood typing is essential for:
  • Safe blood transfusions
  • Organ transplants
  • Pregnancy compatibility
  • Forensic science

Key Terms to Know

• Antigen: A protein or molecule on the surface of red blood cells that triggers an immune response.
• Antibody: A protein in the plasma that attacks foreign antigens.
• Agglutination: Clumping of blood cells due to incompatible antigens and antibodies.
• Rh factor: An additional antigen that can be present (Rh⁺) or absent (Rh⁻) on RBCs.

ABO Blood Group System

• There are four blood types in the ABO system: A, B, AB, and O.
• This system is based on two antigens: A and B.
• The following table summarizes ABO antigens and antibodies:
  • Blood Type A
    • Antigens on RBCs: A
    • Antibodies in Plasma: Anti-B
    • Can Receive From: A, O
    • Can Donate To: A, AB
  • Blood Type B
    • Antigens on RBCs: B
    • Antibodies in Plasma: Anti-A
    • Can Receive From: B, O
    • Can Donate To: B, AB
  • Blood Type AB
    • Antigens on RBCs: A and B
    • Antibodies in Plasma: None
    • Can Receive From: A, B, AB, O (Universal Recipient)
    • Can Donate To: AB
  • Blood Type O
    • Antigens on RBCs: None
    • Antibodies in Plasma: Anti-A and Anti-B
    • Can Receive From: O
    • Can Donate To: A, B, AB, O (Universal Donor)

Rh Factor

• If you have the Rh antigen = Rh positive (Rh⁺).
• If you don’t have the Rh antigen = Rh negative (Rh⁻).
• Rh Compatibility in Transfusions
  • Rh Type: Rh⁺
    • Can Receive Rh⁺ Blood?: Yes
    • Can Donate to Rh⁺?: Yes
  • Rh Type: Rh⁻
    • Can Receive Rh⁺ Blood?: No (can only receive Rh⁻)
    • Can Donate to Rh⁺?: Yes
• Rh⁻ people can’t receive Rh⁺ blood—they’ll form anti-Rh antibodies.
• Rh⁺ people can receive both Rh⁺ and Rh⁻ blood safely.

Blood Typing Reactions (How It Works in a Lab)

• A blood typing test uses anti-A, anti-B, and anti-Rh serums.
  1. A drop of blood is placed in three spots.
  2. Each spot is mixed with:
     • Anti-A antibodies
     • Anti-B antibodies
     • Anti-Rh antibodies
  3. Look for agglutination (clumping):
     • Clumping = that antigen is present.
     • No clumping = that antigen is absent.
• Example:
  • Serum Added: Anti-A
    • Agglutination?: Yes
    • Meaning: A antigen present
  • Serum Added: Anti-B
    • Agglutination?: No
    • Meaning: No B antigen
  • Serum Added: Anti-Rh
    • Agglutination?: Yes
    • Meaning: Rh antigen present
    • → Blood type: A⁺

Inheritance of Blood Type

• Blood type is determined by genes inherited from your parents.
• ABO Gene Inheritance:
  • Alleles: A, B, O
  • A and B are dominant
  • O is recessive
  • Parent Genotype: AO x BO, Possible Child Blood Types: A, B, AB, O
  • Parent Genotype: AB x O, Possible Child Blood Types: A, B
  • Parent Genotype: OO x OO, Possible Child Blood Types: O
• Rh Inheritance:
  • Rh⁺ is dominant over Rh⁻
  • Two Rh⁻ parents can’t produce an Rh⁺ child

Blood Transfusion Rules

• Blood transfusions must match:
  • The ABO type
  • The Rh factor
• Universal Donor/Recipient
  • Type O⁻: No A, B, or Rh antigens = universal donor
  • Type AB⁺: Has A, B, and Rh antigens = universal recipient

Clinical Importance

• Blood Transfusion Reaction:
  • Happens when incompatible blood is transfused
  • Immune system attacks foreign RBCs
  • Can be fatal
• Pregnancy & Rh Factor:
  • If an Rh⁻ mother carries an Rh⁺ fetus, she can develop anti-Rh antibodies
  • In future pregnancies, these antibodies can attack an Rh⁺ baby's blood (called Hemolytic Disease of the Newborn)
  • Prevented with Rhogam injection

Practice Blood Typing Scenarios

• Scenario 1:
  • Anti-A: clumps
  • Anti-B: no clump
  • Anti-Rh: clumps
  • → Blood Type: A⁺
• Scenario 2:
  • Anti-A: no clump
  • Anti-B: clumps
  • Anti-Rh: no clump
  • → Blood Type: B⁻

Summary Chart

• Blood Type A⁺
  • RBC Antigens: A, Rh
  • Plasma Antibodies: Anti-B
  • Can Donate To: A⁺, AB⁺
  • Can Receive From: A⁺, A⁻, O⁺, O⁻
• Blood Type A⁻
  • RBC Antigens: A
  • Plasma Antibodies: Anti-B, Anti-Rh
  • Can Donate To: A⁺, A⁻, AB⁺, AB⁻
  • Can Receive From: A⁻, O⁻
• Blood Type B⁺
  • RBC Antigens: B, Rh
  • Plasma Antibodies: Anti-A
  • Can Donate To: B⁺, AB⁺
  • Can Receive From: B⁺, B⁻, O⁺, O⁻
• Blood Type B⁻
  • RBC Antigens: B
  • Plasma Antibodies: Anti-A, Anti-Rh
  • Can Donate To: B⁺, B⁻, AB⁺, AB⁻
  • Can Receive From: B⁻, O⁻
• Blood Type AB⁺
  • RBC Antigens: A, B, Rh
  • Plasma Antibodies: None
  • Can Donate To: AB⁺
  • Can Receive From: All types
• Blood Type AB⁻
  • RBC Antigens: A, B
  • Plasma Antibodies: Anti-Rh
  • Can Donate To: AB⁺, AB⁻
  • Can Receive From: AB⁻, A⁻, B⁻, O⁻
• Blood Type O⁺
  • RBC Antigens: Rh
  • Plasma Antibodies: Anti-A, Anti-B
  • Can Donate To: O⁺, A⁺, B⁺, AB⁺
  • Can Receive From: O⁺, O⁻
• Blood Type O⁻
  • RBC Antigens: None
  • Plasma Antibodies: Anti-A, Anti-B, Anti-Rh
  • Can Donate To: All types
  • Can Receive From: O⁻

Key Points to Remember for Tests

• A person cannot have antibodies against their own antigens.
• Type O has no antigens, so it's the universal donor.
• Type AB has no antibodies, so it's the universal recipient.
• Rh⁻ blood should never receive Rh⁺ blood.
• Agglutination = incompatible = clumping = dangerous.