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
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