Chapter 03 Fundamentals of Immunology

• The immune system (IS) comprises tissues, organs, cells, and biological mediators that coordinate to defend a host organism against foreign substances or abnormal self-origin cells.
• Immunity is how a host organism protects itself from external and internal threats, offering protection from both nonself and abnormal self-elements, controlled at various levels.
• Nonself organisms include unicellular and multicellular organisms like viroids, viruses, bacteria, mycoplasma, fungi, and parasites and tumor cells.

Immune Response Execution

• Response and eliminating organisms and unwanted cells arise via cellular and/or humoral mechanisms.
• The cellular defense mechanism is mediated by IS cells like macrophages, T cells, and dendritic cells, eliminating viruses, bacteria, cancer cells, and other cellular pathogens.
• Specific antibodies and complement parts are produced in plasma, saliva, and bodily secretions during the humoral mechanism.
• The antibodies attach to cell-specific receptor sites and complement binds immunoglobulin molecules that have specific complement receptor sites.
• The activation's extent and harm to red blood cells rely on the complement pathway and other host factors.

Immunoglobulins Significance

• Immunoglobulins, or antibodies, are critical in transfusion medicine, since antigens on transfused cells might trigger reactions in the recipient and complicate treatment.
• Blood bank testing focuses on preventing, detecting, and identifying blood group antibodies and typing RBC antigens.
• Antigen characteristics and host variables affect immune response, enabling problem solving in testing.
• Understanding the IS and its responses is vital to understanding agglutination reactions between RBCs and antibodies and testing changes.

Antibody Detection

• Detecting alloantibodies or autoantibodies in routine blood bank testing is critical for patient-compatible blood and hinges on factors like antigen-antibody binding forces, antibody features, and individual host traits.
• Distance, antigen-antibody ratio, pH, temperature, and immunoglobulin type all influence antigen-antibody reactions.

Testing Methods

• Traditional and nontraditional lab testing approaches are utilized in the transfusion service to detect antigens or antibodies.
• A summary of immunology and its effect on transfusion medicine including the immune system's biology and biochemistry, and application of testing procedures used in assessing immune response associated with blood transfusion.
• A summary of immune-mediated illnesses significant in transfusion medicine are covered.

Immune System Overview: Basic Concepts

• Organisms face constant environmental challenges and rely on protection against outside factors
• An organism can thrive if it obtains nourishment and security while avoiding the host's IS
• Key concept in immunology is differentiating self vs nonself
• "Self" includes anything from host's genome/rearrangement of host genes ex. cells, fluids, molecules, and complex host constructions
• "Nonself" includes anything physically outside the host; living (parasites, fungus) or nonliving toxin (poison ivy fluid, insect venom)
• IS responds if foreign things/damaged host cells are found
• Immune responses happen at varying degrees and are either primary (natural, innate) or secondary (adaptive, acquired)
• Innate immune response is physical barriers, biochemical effectors, and immune cells
• First step = innate defense externally, also skin and enzymes present on skin
• Second line of innate defense = internal, recognizes common invaders without a specific reaction, ex. phagocytosis primed
• Third line of defense = acquired immune response, needs time to reorganize/mount effective and specific reaction, and protects against repeat attack by organism via immune memory
• IS's specificity stops host from being attacked and harmed during immune response
• Localized immune reactions prevent systemic damage in host
• Wide array of possible organisms/substances requires a vast array of ways to recognize/remove them
• Acquired immune response can generate many specific responses to complex organisms/substances over lifetime

Cellular and Humoral Immunity

• The vertebrate IS has two primary parts: cellular immunity and humoral immunity.
• Cellular immunity: Mediated by IS cells: macrophages, T cells, and dendritic cells which function to viruses, bacteria, cancer cells, and cellular pathogens elimination
• Lymphokines: Activating and deactivating cells allows cellular system communication since they are other effector chemicals that facilitate vital cellular system activities
• Humoral immunity: IS fluid segments, like antibodies and complement elements, is present found in plasma, saliva, and secretions
• Antibodies: Also known as immunoglobulins as globular soluble proteins, antibodies attach to foreign molecules known as antigens
• Most antigens located on foreign cells' surface or broken internal cells
• Antigen-antibody reactions: Their specificity is a main element.
• Antibody: Reacts with specific antigens or part (epitope and antigenic determinant) of complex antigen and it stimulates antibody production that matches antigen epitope
• Binding reaction: Interaction called lock and key mechanism is because of specific configuration. The reactions inactivating the Antigen-Antibody complex leads to elicit a large number of complicated effector processes that result towards the antigen destruction, including the destruction of cells bound

Serology: Lab tests

• Antigen-antibody reactions which study laboratory has served as blood bank technology foundation for many years.
• Antibody screening: Approaches like indirect antibody assays and crossmatching procedures depends on antigen-antibody complexes test by screening plasma or serum for antibodies
• Direct antiglobulin: Coombs, examines for surface of red blood cell-bound antibodies and complement

Immunity: Innate vs Acquired

• Manner to describe the IS is via its cell along side humoral components

• Prevent infection and eliminate host-destroying damaged cells require immune cell

• Innate part: Less sophisticated and more ancient is more ancient which recognizes common invading organisms with complex patterns

• Part acts quick stopping host organism

• Acquired immune response created after vertebrates created is the main process. It relies on specific cellular responses and antibody complex

Table 3-2: Cellular and Humoral Components of the Immune System

• Innate or Natural Immunity
• First Line of Defense (Physical)
  • Intact skin
  • Mucous membranes
  • Cilia
  • Cough reflex
• Internal Components (Cellular)
  • Phagocytic cells
  • Macrophages-dendritic cells
  • Monocytes
  • PMNs: Large granular leukocytes
  • NK cells
• Internal Components (Humoral/Fluid)
  • Complement-alternate pathway
  • Cytokines
  • Interferons
  • Interleukins
  • Acute inflammatory rxn
• Acquired or Adaptive Immunity
  • Third Line of Defense (Cellular)
    • Lymphocytes
    • T Cells and Subsets
    • B Cells
    • Plasma Cells
• Third Line of Defense (Humoral)
  • Antibodies
  • Complement-classic pathway
  • Cytokines

Important Innate Immunity Features

• Non-specificity: Same response against organisms, wherever they are from if IS can identify being non-self, has the same effect
• Presence at birth without learning or acquiring
• No need for maintenance and no changes needed to take action over exposure to the same antigen

Innate System Makeup

Physical barriers, biochemical barriers and cells

• Physical Barriers
• Includes - intact, mucous membranes, cilia that create a barrier Biochemical Barriers
• Enzymes that kill that include lysozyme/enzymes
• Fatty acids
• Stomach acid
• Innate Cells
  • Leukocytes with phagocytes/killer(NK) cells
  • Killer NK cells that are more available in many organ and tissues, they kill pathogens
• Phagocytes
  • move between vessel walls that can recognize and breakdown cells, and cause the surface structure changes that lead to enzyme reactions

Removing pathogens via phagocytosis is driven by cells

• Polymorphonuclear Cells: Neutrophils
• Mononuclear Cells: Monocytes
• The cells and collaboration of other cells, need other factors such Opsonins include factors of complement factors that coat and cause better reaction
• Phagocytes that remove cells, release soluble substances of polypeptide (cytokines): They affect Table 3 cells of vascular parts of immune system functions- Some function well together, other oppose the functions as membrane receptors
• Cytokines
• Regulation requires duration of intensity.
• System consist of three: Final lysis of both abnormal or either by the binding part of the antibody complement
• Proteins use enzymes when found when inactive

Complement Immunity

• First, classic, alternative pathway where all have final results of lysis and inflammation

• Classic: Uses antigen combining for a specific activator

• Alternative: Utilizes surface structure activation like tumors and is known when activated with mannose binding

• Inflammation drives with warmth. Redness can be driven by infection or burns

• Tissue damage that initiate by cells within site like burns the blood flow increases for mobilized phagocytic action

• Acquired- Adapt to new process of the type in pathogens

• Adaptive refers to the ability to destroy and change the but have reactions over recognition processes

Immune Responses:Acquired

• uses antibodies when the immune effects are specific- for something only the uniqueness drives for 3d that has to understand example blood group and if there is reaction
• fact there are the ones that need medical histories
• always reamin high and if transfuses reatin is vigoruous

Cell and Organ and Response of IS

• the 3d structure

• Different cell types in the surface, distinction of membrane =Cluster of determination

• Process requires cells and tissues where the system that innate monocytes

• Lymphocytes needed where two major are b/t. B: marroq they will need to be stimulated

• Natural: lymphocyte

Cell immune protection with body cell response

• dendritic antigen
• communitcate by corre correct react

Immune-Cytokine and Molecules/Regulatory

• Proteins responsible are what power
• 2 main are cytokine produce Lymph is lymph
• Cytokines regulate growth by themselves function in a very complexed fashion.
• Immune cells react via chemo at

Immune Response: Genetics

• Individuals each have unique immunity resistance,
• Familal pattern susceptiblity can show where banking is

Important where not all the receipients produce antibodies on RBC if response is high, low to antibodies. Single spiciity over time in the cell it can with that same specify