NCLEX - Theory

Must-Know Blood Type

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Must-Know “Blood Type”

ANTIGENS

(Must-Know “Blood Type”)

Antigens are specific proteins or molecules found on the surface of red blood cells. These antigens determine an individual’s blood type and play a crucial role in blood transfusions.

PLASMA ANTIBODIES

Plasma antibodies are proteins found in the plasma (the liquid component of blood) that play a crucial role in the immune system. They are produced by B cells (a type of white blood cell) in response to the presence of foreign antigens, such as those found on the surface of bacteria, viruses, or mismatched red blood cells during a transfusion.

Key Points About Blood Antigens:

ABO System Antigens:
- A Antigen: Present on red blood cells in individuals with type A blood.
- B Antigen: Present on red blood cells in individuals with type B blood.
- AB Antigens: Both A and B antigens are present on red blood cells in individuals with type AB blood.
- No A or B Antigens: Individuals with type O blood have no A or B antigens on their red blood cells.
Rh Factor (Rhesus Antigen):
- Rh Positive (Rh+): Individuals have the Rh antigen (also known as the D antigen) on their red blood cells.
- Rh Negative (Rh-): Individuals lack the Rh antigen on their red blood cells.

Must-Know Blood Type

Importance of Blood Antigens:

Blood Type Determination: The combination of ABO antigens and the Rh factor determines a person’s blood type (e.g., A+, O-, etc.).
Blood Transfusions: Compatibility between the donor’s and recipient’s blood antigens is crucial for safe transfusions. Receiving blood with incompatible antigens can trigger an immune response, leading to serious complications.
Pregnancy: If an Rh-negative mother is carrying an Rh-positive baby, the mother’s immune system may produce antibodies against the baby’s Rh antigens, potentially leading to hemolytic disease of the newborn (HDN).

Key Functions of Plasma Antibodies:

Neutralize Pathogens: Antibodies bind to specific antigens on the surface of pathogens (e.g., bacteria, viruses) to neutralize them, preventing them from infecting cells.
Mark for Destruction: When antibodies bind to antigens, they mark the pathogen for destruction by other immune cells, such as macrophages, which engulf and destroy the pathogen.
Activate Immune Responses: Antibodies can activate other parts of the immune system, such as the complement system, which helps to clear pathogens from the body.

Must-Know “Blood Type”

Plasma Antibodies in Blood Types (ABO System):

In the ABO blood group system, plasma antibodies are specific to the antigens that are not present on a person’s red blood cells:

- Type A: Has anti-B antibodies in the plasma (against B antigens).
- Type B: Has anti-A antibodies in the plasma (against A antigens).
- Type AB: Has no anti-A or anti-B antibodies in the plasma (can receive any ABO type blood).
- Type O: Has both anti-A and anti-B antibodies in the plasma (against both A and B antigens).

Importance in Blood Transfusions:

During a blood transfusion, it’s crucial that the donor’s red blood cells do not have antigens that match the recipient’s plasma antibodies. If they do, the antibodies in the recipient’s plasma will attack the donor’s red blood cells, causing a potentially dangerous reaction.