RBC Blood Transfusions

RBC REACTIONS - Dr. Francina Towne

READING ASSIGNMENT

  • Textbook: Basic Immunology: Functions & Disorders of the Immune System, Abbas & Lichtman

  • Pages to Read: 215-216

  • Figures to Preview: Figure 10-15 and the accompanying PowerPoint presentation.

LEARNING OBJECTIVES

  • Define and Discuss Agglutination: Understand the significance and mechanism behind agglutination.

  • Describe the ABO Blood Groups: Understand the characteristics of ABO blood groups and the Bombay blood type.

  • Compare and Contrast Histocompatibility: Assess differences between the ABO and Rh blood groups.

  • Blood Typing Results: Learn how to interpret and predict blood typing results.

  • Cross-Match Test Importance: Explain the process and significance of cross-matching blood before transfusions.

  • Understanding Recipients Serum and PRBCs: Define recipient's serum and packed red blood cells (PRBCs). Identify plasma contents.

  • Matching Donor Plasma: Discuss procedures for matching donor plasma to the recipient.

  • Transfusion Reactions: Compare different types of transfusion reactions that may occur.

  • Hemolytic Anemia Mechanism: Understand the mechanisms involved in hemolytic anemia.

  • RhoGAM Shot: Describe the RhoGAM shot and its applications in clinical practice.

AGGLUTINATION

  • Definition: Agglutination refers to the process where clumps (agglutinates) form when particulate antigens (e.g., whole cells) combine with corresponding antibodies.

  • Importance: It serves as evidence of an antigen-antibody reaction, resulting in a positive diagnostic test.

  • Hemagglutination: A specific type of agglutination test where the clumping of red blood cells (RBCs) indicates a positive result. It is primarily used for detecting A, B, and Rhesus (Rh) antigens.

BLOOD TRANSFUSION

  • Overview: Blood transfusion is a common clinical transplantation procedure.

  • Statistics: Approximately 25% of the population will require a blood transfusion at some stage in their life.

  • Importance of Matching Blood Types: Correct blood type matching is crucial to prevent adverse transfusion reactions.

STRUCTURES OF THE ABO BLOOD GROUP

  • Antigens Present on RBCs:

    • O Antigen

    • A Antigen (GalNAc)

    • B Antigen (Gal)

    • Structures include Fucose and Galactose residues.

ABO GENES

  • Genetic Traits:

    • A and B alleles are dominant over the O allele.

    • A and B alleles are codominant.

    • O allele is recessive.

  • Genotype Notation: Black text denotes genotype, and red denotes blood type.

ANTIGENS AND ANTIBODIES IN BLOOD GROUPS

  • Track presence of antigens vs antibodies in serum:

    • Difference between Plasma and Serum: Plasma includes clotting factors, while serum does not.

BLOOD DONORS AND RECIPIENTS

  • ABO Blood Group Matching:

    • Recipients with type A blood have anti-B antibodies and so forth.

    • Compatibility is necessary to prevent immune reactions.

ANTI-A AND ANTI-B ANTIBODIES IN TYPE O BLOOD

  • Individuals with type O blood develop anti-A and anti-B antibodies through environmental exposure and not inheritance.

RH (RHESUS) BLOOD GROUP SYSTEM

  • Rh+ Definition: Presence of the “D” antigen indicates Rh positive status.

  • Rh- Population: 15% may carry a deletion or alteration in the RhD allele, leading to Rh negative status.

  • Inheritance Patterns: Rh+ is dominant and Rh- recessive, following Mendelian inheritance principles.

BLOOD TYPING SUMMARY

  • Purpose: To determine which antigens are on the surface of the sample's cells.

  • Procedure & Example Card:

    • Utilize synthetic antibodies and toothpicks to identify antigens, NOT focusing on antibodies present in the serum sample.

INTERPRETING BLOOD TYPES


  • Agglutination Reactions:

    Antiserum

    Anti-A

    Anti-B

    Anti-Rh

    Interpretation


    Yes

    A+

    Yes

    A antigen present; B antigen absent; Rh antigen present


    Yes

    A-

    No

    A antigen present; B antigen absent; Rh antigen absent


    No

    B+

    Yes

    B antigen present; A antigen absent; Rh antigen present


    No

    O-

    No

    A and B antigens absent; Rh antigen absent

    EXCEPTIONS IN BLOOD TYPING

    • Non-identical Twins: Chimeric blood may occur when siblings share blood circulation.

    • Multiparous Women: May have retained cells from previous pregnancies (micro-chimerism).

    • Bombay Blood Group: Rare variants of blood types necessitate diligent cross-matching.

    BOMBAY BLOOD GROUP

    • Characteristics:

      • Occurs in 4 people per million overall and in 1 per 10,000 in Mumbai.

      • Lacks fucose residue, appears as type O but has antibodies against A, B, and O.

      • Must receive blood only from Bombay blood group individuals.

    CROSS-MATCH TEST

    • Purpose: To eliminate risk of unexpected transfusion reactions.

    • Procedure: Tests recipient's serum against donor RBCs, NOT against donor serum to avoid false matches.

    TYPICAL BLOOD TRANSFUSIONS

    • Components Used:

      • Packed Red Blood Cells (PRBCs); a combination of whole blood and anticoagulant.

      • Whole blood is rarely used unless there’s massive loss.

    • Infection Screening: All blood products are screened for various infectious diseases (e.g., Hepatitis B & C, HIV, etc.).

    TYPES OF BLOOD TRANSFUSION REACTIONS

    1. Hemolytic Transfusion Reactions:

      • Type II hypersensitivity response.

      • Acute reactions may lead to severe symptoms (fever, chills, shock).

      • Treatment Protocols: Stop transfusion, maintain blood flow, treat shock symptoms.

    2. Allergic Reactions:

      • Type I hypersensitivity response often related to plasma proteins.

      • Symptoms include wheezing and urticaria.

      • Treatment: Antihistamines.

    3. Anaphylactic Reactions:

      • Severe allergic response; can be life-threatening.

      • Examples: Patients deficient in IgA must avoid IgA-containing products.

      • Treatment Procedures: Stop transfusion, administer rescue medications like adrenaline.

    4. Febrile Non-Hemolytic Transfusion Reaction:

      • Most common type II hypersensitivity reaction.

      • Symptoms include fever and chills without hemolysis.

      • General Care: Treat with fever reducers, monitor closely.

    UNIVERSAL RBCs AND STEM CELL RESEARCH

    • Research into producing universal red blood cells is ongoing due to declining blood donations.

    • Challenges: Though methods using stem cells show promise, mass production remains complicated.

    NEW ROLES OF RBCs IN IMMUNE RESPONSE

    • Recent studies suggest RBCs play active roles in innate immune activation, contradicting old beliefs of them being immunologically inert.

    • Findings: RBCs express TLR9 and can bind DNA from pathogens, leading to inflammation and anemia.

    HEMOLYTIC DISEASE OF THE NEWBORN (HDNB)

    • Mechanism in Rh- Mother and Rh+ Child: Antibodies formed during the first pregnancy attack fetal RBCs in subsequent pregnancies if the mother is Rh-.

    • RhoGAM Usage: Administered during pregnancy (28 weeks) and post-birth to prevent sensitization and subsequent fetal anemia.

    • Effects of RhoGAM: Prevents antibody response by binding to any Rh+ fetal cells that may enter the maternal circulation.