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Immunohematology, blood group typing, disease and transfusion

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Introduction to Immunohematology

Immunohematology is a specialized field that combines principles from immunology and hematology to understand the interactions between blood components and the immune system. It primarily focuses on blood group systems and their implications for blood transfusion and related medical conditions.

Blood is composed of four main components:

  1. Plasma (55% of blood): The liquid portion that contains water, electrolytes, proteins (like albumin, fibrinogen, and antibodies), nutrients, hormones, and waste products.
  2. Red Blood Cells (RBCs) (45% of blood): Also called erythrocytes, these cells carry oxygen from the lungs to the body’s tissues and bring carbon dioxide back to the lungs.
  3. White Blood Cells (WBCs): Also known as leukocytes, these cells are involved in the immune response and help protect the body from infections and foreign invaders.
  4. Platelets (Thrombocytes): These small cell fragments help with blood clotting to stop bleeding when blood vessels are injured.

Understanding the immune system, which is the body’s defense mechanism is fundamental to immunohematology, as it governs how the body responds to foreign antigens, including those present on blood cells.

In context of immunohematology two important key Components are :

Each species of animal including human, has certain antigen unique to that species which are usually present on the rd cell membrane of the member of that species.

Even within the member of the same species there can be antigen found on the surface of the blood cells of some, that are not from on the red blood cells of other. And some antigen are more common then other.

Blood Groups and Antigens

Based on the presence or absence of the of those antigen the red blood cells can be caterorised in different groups. These antigens are inherited and can affect transfusion compatibility and immune responses.

            Hundreds of known RBCs antigen have been organized into 30 blood group system. Some of the more common blood group system are- ABO, Rh, Kidd, MNS, Lewis, Kell and Duffy.

ABO Blood Group System:

Each group has two gene for any train. It can have following combination fof allele aor genotype –

Landsteiner Rule

if A or B antigen is not present on the surface of the red blood cells the corresponding antibody will be found in the serum.

Example –

            A person lacking the A antigen on the surface of their RBCs, will have anti A  antibody in their plasma or serum.

This occure only in ABO system

Rh Blood Group System:

Other Blood Group Systems:

From this chart we can see that

Note – This chart is for only RBCs transfer not whole blood.

Figure – Plasma Compatibility ( for plasma O is universal recipient and AB is universal donor.)

Blood Typing and Crossmatching

A. Techniques for Blood Typing

  1. Forward Typing (Reagent Typing):
    • This test identifies the blood group by mixing a patient’s red blood cells with known anti-A and anti-B reagents. The presence or absence of agglutination (clumping) determines the ABO blood type.
    • Results Interpretation:
      • Agglutination with anti-A reagent indicates Type A blood.
      • Agglutination with anti-B reagent indicates Type B blood.
      • Agglutination with both indicates Type AB blood.
      • No agglutination with either indicates Type O blood.
  2. Reverse Typing (Serum Typing): This test involves mixing the patient’s serum (containing antibodies) with known A and B red blood cells to detect the presence of anti-A and anti-B antibodies.
    • Results Interpretation:
      • Presence of anti-A antibodies reacts with Type A red blood cells.
      • Presence of anti-B antibodies reacts with Type B red blood cells.
      • The pattern of agglutination helps confirm the blood group.

B. Crossmatching Procedures

  1. Major Crossmatch: To ensure that the recipient’s antibodies do not react with the donor’s red blood cells.
    • Mix a sample of the recipient’s serum with donor red blood cells. If no agglutination occurs, the blood is considered compatible for transfusion.
  2. Minor Crossmatch: To check if the donor’s plasma antibodies react with the recipient’s red blood cells.
    • Mix a sample of donor plasma with recipient red blood cells. This test is less commonly performed today due to advances in blood typing technology but is useful in certain complex cases.

C. Importance in Preventing Transfusion Reactions

Blood Transfusion and Immunohematology

If blood containing foreign antigen on the surface of red blood cell is transferred into recipient whose red blood cells do not have that antigen, the recipient form antibody to that particular antigen.

Once those antibody are present in the recipients plasma future transfusion of RBCs with that antigen on their surface can cause a significant, possibly even life threatening, adverse immune response termed a transfusion reaction.

The primary goal of blood transfusion in immunohematology is to ensure that the blood transfused does not provoke an immune reaction that could harm the recipient. Key considerations include:

Types of Transfusion Reactions

  1. Hemolytic Reactions:
    • Acute Hemolytic Reaction: Occurs immediately or within hours of transfusion due to ABO incompatibility. Symptoms include fever, chills, back pain, and hemoglobinuria.
    • Delayed Hemolytic Reaction: Occurs days to weeks after transfusion, often due to Rh or other minor antigen incompatibilities. Symptoms can include anemia and jaundice.
  2. Allergic Reactions:
    • Mild Allergic Reactions: Include symptoms like itching, rash, and urticaria. These are usually manageable with antihistamines.
    • Severe Allergic Reactions (Anaphylaxis): Rare but severe reactions that can cause difficulty breathing and hypotension. Immediate treatment with epinephrine and supportive care is required.
  3. Febrile Non-Hemolytic Transfusion Reaction (FNHTR):
    • Cause: Often caused by cytokines released from leukocytes in the transfused blood.
    • Symptoms: Fever, chills, and sometimes headache. It is generally managed with antipyretics and is usually self-limiting.
  4. Transfusion-Related Acute Lung Injury (TRALI):
    • Cause: Associated with antibodies in donor plasma that react with recipient leukocytes, leading to lung inflammation.
    • Symptoms: Sudden onset of respiratory distress and hypoxemia. Requires prompt recognition and supportive respiratory care.

 Condition /Disease due to blood incompatibility

Hemaolytic anemica of newborn

Hemolytic anemia of the newborn (also known as neonatal hemolytic disease) occurs when a newborn’s red blood cells are destroyed faster than they can be produced, leading to anemia (a low red blood cell count). It is commonly caused by an immune reaction where antibodies from the mother attack the baby’s red blood cells.

The two main causes are:

  1. Rh Incompatibility: This occurs when the mother is Rh-negative and the baby is Rh-positive. The mother’s immune system may produce antibodies against the baby’s Rh-positive red blood cells, leading to their destruction.
  2. ABO Incompatibility: This occurs when the mother and baby have different blood types, most often when the mother is type O and the baby is type A or B. The mother may produce antibodies against the baby’s red blood cells, leading to their breakdown.

Symptoms:

Treatment:

 Autoimmune hemolytic anemia

Autoimmune Hemolytic Anemia (AIHA) is a condition where the body’s immune system mistakenly attacks and destroys its own red blood cells, leading to anemia (a shortage of red blood cells). This can result in a reduced ability to carry oxygen to tissues, causing symptoms like fatigue, pallor, and shortness of breath.

Types of Autoimmune Hemolytic Anemia:

  1. Warm Antibody AIHA:
    • The most common form, where antibodies (usually IgG) attack red blood cells at normal body temperature (37°C).
    • It is often associated with conditions like autoimmune diseases (e.g., lupus), infections, or certain cancers.
  2. Cold Agglutinin AIHA:
    • In this form, antibodies (usually IgM) attack red blood cells at lower temperatures, typically below body temperature.
    • This is often triggered by infections (like Mycoplasma pneumonia or Epstein-Barr virus) or can be idiopathic (of unknown cause).
  3. Mixed AIHA:
    • A combination of both warm and cold antibody reactions.

Symptoms:

Causes:

AIHA can be primary (with no underlying cause) or secondary to other conditions like:

Diagnosis:

Treatment:

AIHA can be a chronic condition, but with appropriate treatment, most individuals can manage the symptoms and improve their quality of life.

Symptoms, Diagnosis, and Management

  1. Recognition:
    • Monitoring: Vigilant monitoring during and after transfusion for any signs of reactions.
    • Symptoms: Immediate symptoms often indicate acute reactions, while delayed symptoms can signal a chronic reaction or complications.
  2. Diagnosis:
    • Laboratory Tests: Blood samples from the recipient and donor may be tested to identify the cause of the reaction.
    • Clinical Evaluation: Detailed assessment of symptoms and timing relative to transfusion helps in diagnosis.
  3. Management:
    • Immediate Action: Stop the transfusion immediately and provide supportive care as necessary.
    • Notification: Inform the blood bank and document the reaction in the patient’s medical record.
    • Treatment: Depending on the type of reaction, treatment may include medications, fluid management, and supportive care.

Prevention Strategies

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