Medical Technology



Clinical Laboratory Science:

Immunohematology and Immunology


Immunohematology


Immunohematology is the study of antigens and antibodies associated with blood transfusion and some complications of pregnancy. The application of this knowledge base in CLS is commomly known as Blood Banking or Transfusion Medicine. While safe transfusions of blood and blood products are the main focus of blood banking, larger institutions may be concerned with the immunology of tissue or organ transplantation.

Reactions between RBC antigens and specific (and nonspecific) plasma antibodies result in the coating and destruction of RBCs. A rapid destruction of RBCs releases free hemoglobin into the circulating plasma which may result in renal shutdown, toxemia and death; hence, extreme precautions are taken to ensure safe, compatible transfusions.

A comprehensive understanding of transfusion medicine requires an understanding of immunology, serology and genetics. Recent innovations (<20 years) in enzymatic, recombinant DNA and other biomedical techniques are rapidly expanding the frontiers of knowledge of immunogenetics. Nevertheless, a practical level of knowledge of these subjects is sufficient and satisfactory for the performance of most tasks associated with immunohematology. Crossmatching to confirm transfusion-compatible blood, detection and identification of natural and unexpected antibodies, provisioning and preparation of blood components and their derivatives and detection of hemolytic disease of the newborn (HDN) are among the the most commonly performed immunohematology tasks.

RBC Antigens and Antibodies

An antigen is a substance which elicits the formation of a water soluble, plasma glogular protein known as an antibody. RBC antigens are fixed protein or lipoprotein structures incorporated in the lipid membrane of the RBC. Formation of human RBC antigens are coded by specific nuclear DNA loci and composition known as genes. Since RBC antigens are DNA specific, if one is born with an antigen, he has it for life. Associated inherited variations of alellic genes gives rise to the classifying of antigens into associated groups, i.e., ABO, Rh, Kell, Kidd, Duffy, MNS and others.

An antibody is a globular protein which is manufactured by plasma cells in response to an antigenic stimulus. In normal adults there is about 3 grams of globulin per dL of plasma (3%), most of which is either an immunoglobulin antibody, enzyme or transport protein. The immunoglobulin fraction may be further classified by immunoelectrophoresis into immunoglobulins IgA, IgD, IgE, IgG, and IgM.

(more will follow)


Listed below is the table of contents of the Transfusion Medicine Manual from the UCLA Medical Center. The manual is compact, yet provides much practical information on blood group antigens, antibodies and compatibility testing. Chapter links to their sources are provided.

Transfusion Medicine Manual
University of California, Los Angeles, Division of Transfusion Medicine

TABLE OF CONTENTS

Chapter 1 - Fundamentals of Transfusion Medicine

      Blood Group Systems
      The ABO Blood Group System
      Biochemistry and Inheritance of the ABO Groups
      The Rh Blood Group System
      Other Blood Group Systems
      Consequences of Antibodies to Red Blood Cells
      Serologic Tests for Red Cell Antibody Detection
      The HLA System
      HLA and Transfusion
      HLA and Transplantation
      HLA and Parentage Testing
      HLA and Disease
      References

Chapter 2 - Compatibility Testing

      What a Physician Needs to Know About Compatibility Testing
      Blood Sample
      ABO Typing
      Rh Typing
      Antibody Screen
      Crossmatch Tests
      Routine Compatibility Testing Policies
      Surgical Blood Ordering
      Type and Crossmatch
      Type and Screen
      Hold Clot
      Surgery without a Blood Order
      Maximum Surgical Blood Order Schedule (MSBOS)
      Emergency Transfusion
      Group O, Rh-negative Red Cells, Uncrossmatched
      Type Specific Blood, Uncrossmatched
      Circumstances in Which it is Difficult or Impossible to Find Compatible Blood
      "In Vivo Compatibility Test"
      Relationship of Compatibility Tests to Fatal Hemolytic Transfusion Reactions
      References

Chapter 3 - Blood Donation

      General Donor Requirements
      Donation Process
      Medical History Review
      Blood Donation
      Donor Testing
      ABO and Rh
      Antibody Screen
      Tests Intended to Prevent Disease Transmission
      Autologous Donor Programs
      Preoperative Collection
      Hemodilution
      Intra/Post Operative Autologous Blood Collection
      Designated Donor (DD) Programs
      Apheresis Programs
      Component Collection
      Therapeutic Apheresis Procedures
      References

Chapter 4 - Informed Consent, Infectious Complications of Transfusion, and Transfusion Alternatives

      Informing the Patient and Obtaining Consent for Transfusion
      Infectious risks of Blood Transfusion
      Progression of Transfusion Transmitted Infection to Disease
      Transfusion Alternatives
      References

Chapter 5 - Blood Administration

      Prior to Transfusion
      Transfusion Equipment
      Blood Infusion Sets
      Needles and Catheters
      Leukocyte-Removing Filters
      IV Pumps
      Pressure Bags
      Blood Warmers
      IV Solution and Medications
      Confirming Patient and Donor Identity
      Monitoring the Patient During Transfusion
      Infusion Rates
      Transfusion Follow-up
      References

Chapter 6 - Transfusion Reactions

      Signs and Symptoms to Watch for
      Refer to the Following Pages for Treatment of Life-threatening Reactions
      Immediate Action to Take for all Suspected Reactions
      Laboratory Response
      Reaction Classifications
      Hemolytic - Immune, Acute (AHTR)
      Hemolytic - Immune, Delayed (DHTR)
      Hemolytic - Non-immune
      Febrile Nonhemolytic Reactions
      Allergic Reactions
      Anaphylactic Reactions
      Transfusion Related Acute Lung Injury (TRALI)
      Circulatory Overload
      Bacterial Contamination
      Metabolic Complications
      Transfusion-Transmitted Disease
      References

Chapter 7 - Transfusion Practices

      Transfusion of Red Blood Cells
      Transfusion of Red Blood Cells for Anemia
      Transfusion of Red Blood Cells in Surgery
      Platelet Transfusion
      Indications for Platelet Transfusion
      Determining the Appropriate Dose of Platelets
      Monitoring the Effectiveness of Platelet Transfusions
      Special Platelet Products for Refractory Patients
      Fresh Frozen Plasma
      Cryoprecipitate
      Granulocyte Transfusion
      Albumin
      Special Blood Products
      Leukocyte-Reduced Blood Components
      Irradiated Blood Products for Prevention of Transfusion-Associated Graft-versus-Host Disease
      Blood Products for Prevention of Transfusion-Transmitted Cytomegalivirus (CMV) Infection
      Intravenous Immunoglobulin (IVIg)
      Rh Immune Globulin
      Fibrin Glue
      Transfusion in Specific Clinical Settings
      Pediatric and Neonatal Transfusion Practices
      Hemolytic Disease of the Newborn
      Neonatal Alloimmune Thrombocytopenia (NAIT)
      Transfusion of Patient with Sickle Cell Diseaes
      Transfusing Recipients of ABO-Mismatched Bone Marrow and Solid Organ Transplants
      Massive Transfusion
      Transfusion Management of Hemorrhagic Disorders
      Congenital Deficiencies
      Acquired and Secondary Disorders of Hemostasis
      Transfusing Patient with Autoimmune Hemolytic Anemia (AIHA)
      Therapeutic Apheresis
      Immune Consequences of Transfusion
      Indication and Guidelines for the Use of Hematopoietic Growth Factors
      References
      Appendix - Quick Reference to Blood Component Therapy
      Blood Components and Derivatives
      Preservation and Storage
      Labeling and General Information

Chapter 8 - Transfusion Medicine Education Study Guide

      Medical Student Objectives
      References

Chapter 9 - UCLA Policies - Quick Reference Guide

      Essential Phone Numbers
      Important References Available At Nursing Stations
      Blood Bank Forms
      Blood Availability Time Table
      UCLA Transfusion Audit Criteria
      Special Blood Products
      Test Sample Requirements
      Informed Consent for Transmission
      Confirming Patient/Donor Identity Before Transfusion
      Patient Care During Transfusion
      If Transfusion Reaction Is Suspected
      Relationship between CCI and PPR




Immunology


Until I am inspired to compile text which is applicable to immunology as practiced in CLS, the hypertext link below will serve. The reference below is to the online version of Essentials of Immunology by Andy Reese and William Dolen from The Medical College of Georgia. Click here to go to those web pages.

Essentials of Immunology is not intended to be a comprehensive reference for the field of immunology, but is an attempt to provide a comprehensive, manageable update on the general field which is not easily available in other forms.

                                 Chapters

                     Nonspecific Defense Mechanisms 

                     Complement 

                     Structure, Function, & Genetics of Immunoglobulins 

                     Antigen-Antibody Reactions 

                     Cells & Tissues of the Immune System 

                     Antigen Induced Lymphoproliferation 

                     Control of Immune Responses 

                     Immune Responses to Infections 

                     Atopy (Allergy) 

                     Immunopathology 

                     Tolerance and Autoimmunity 

                     Immunodeficiency Diseases 

                     Immunobiology of Transplantation 

                     Immunobiology of Cancer 

                     Intervention in the Immune Response

Clinical Chemistry Microbiology

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