Blood Grouping Principals

Blood is a fluid connective tissue that circulates throughout the body and is responsible for transporting oxygen, nutrients, hormones, and waste products. It is also important for maintaining homeostasis, immune response, and clotting. Blood is composed of 55% plasma and 45% formed elements including red blood cells, white blood cells, and platelets.

1. Red Blood Cells (RBCs): RBC transports oxygen throughout the body.
2. White Blood Cells (WBCs): WBC are an important part of the immune system and defends against infections.
3. Platelets: Platelets aid in blood clotting and prevents excessive bleeding.
4. Plasma: It forms liquid component of blood and carry nutrients, hormones, and waste products.

Blood grouping also known as a ABO Blood Group system is based on the presence or absence of specific antigens and antibodies in the blood. Karl Landsteiner discovered the ABO blood group system in 1901.  The two most important blood group systems are the ABO system and the Rh system.

• ABO System
  • Blood is classified into four main groups: A, B, AB, and O, based on the presence or absence of antigens (A or B) on red blood cells.
  • Individuals inherit one ABO gene from each parent, resulting in specific blood types.
  • Blood type O has neither A nor B antigens, A and B types have their respective antigens, and AB type has both.
• Rh System
  • Rh factor (Rhesus factor) determines whether blood is Rh-positive or Rh-negative.
  • If the Rh factor is present, the blood type is positive (e.g., A+, B+), and if absent, it is negative (e.g., A-, B-).
  • Rh factor inheritance is independent of ABO blood group inheritance.
• Antibodies and Agglutination
  • Anti-A and anti-B antibodies in the plasma react with foreign antigens.
  • Agglutination (clumping) occurs when antibodies react with incompatible antigens.
  • Testing involves introducing blood to anti-A, anti-B, and anti-Rh antibodies to observe reactions.
• Compatibility
  • Blood transfusions and organ transplants require compatibility between donor and recipient blood types to prevent adverse reactions.
• Universal Donor and Recipient
  • Type O negative (O-) is considered a universal donor as it lacks A, B, and Rh antigens.
  • Type AB positive (AB+) is a universal recipient as it can receive blood from any type.

Also Read: Difference Between Antigen and Antibody

Blood Group Testing determines a person’s blood type based on the presence or absence of specific antigens and antibodies in the blood. The blood test involves mixing a sample of blood with antibodies against type A and B blood. Common blood types are A, B, AB, or O, along with Rh-positive or Rh-negative. A blood sample is collected, and antibodies react with A, B, and Rh antigens to identify the blood group. Results help ensure safe blood transfusions, and organ transplants, and manage pregnancy risks.