Exam 3 (Immunology) Flashcards
Immunology
- The branch of science that studies the response of the body when challenged by antigens
- The body’s defense against the environment
Immunity
What protects an animal from D2 causing pathogens
Pathogen
D2 producing organism
Resistance
Ability to ward of D2 by body’s defense
Susceptibility
Vulnerability or lack of resistance
Pus
Collection of dead cells and fluid
Abscess
Accumulation of pus in a confined space
Ulcer
Open inflamed tissue on surface of an organ
Immune System Components
Physical barriers
Non-specific immunity (innate immunity)
Specific immunity (adaptive immunity)
Physical Barriers (Mechanical)
First line of defense
-Generalized protection, does not initiate a specific response against a specific antigen
Mechanical (movement):
- Skin + mm
- Cilia
- Lacrimal apparatus
- Flow of urine, defecation, and vomiting
Physical Barriers (Chemical)
First line of defense
-Generalized protection, does not initiate a specific response against a specific antigen
Chemical:
- Sebum-antibacterial properties
- Perspiration
- Gastric fluid
- Vaginal secretions
Nonspecific Immunity (Innate)
Second line of defense
- Inflammatory response
- Fever
- Antimicrobial proteins
- Phagocytosis
- Natural Killer Cells (NKC)
Interferon
-Protein released by cell to inhibit spread and growth of virus
Transferrin
-Protein attaches to iron and transports into marrow so bacteria can’t utilize for survival
Complement
-Inactive protein stored in plasma, becomes active during infection and attaches to antigen and destroys it
Specific Immunity (Adaptive)
3rd line of defense
- Ability of the body to target and destroy specific antigens
- Lymphocytes involved
- Properties of Specific Immunity:
1. Able to specify for particular antigens
2. Has memory of previous antigens and produces rapid and vigorous response during 2nd encounter
Antibody
Proteins produced by plasma cells in response to antigen
Immunogenicity
Ability to provoke immune response in animal
Reactivity
Ability of antigen to produce specific reaction
Cell-Mediated Immunity
- Involves T cells which have specific antigen receptors on cell membranes (unique to one antigen)
- Antigen ingested by macrophage and presented on cell membrane
- T cell attaches to antigenic site and becomes sensitized T cell
- Then clones itself into army of cytotoxic cells who in turn attach to antigen
Cytotoxic T Cells (Sensitized T Cell)
- Similar to NKC but had to be “trained”
- Killer T Cells
- Attach to antigenic cells and destroy them directly
Helper T Cells (Sensitized T Cell)
- “Bottom of pyramid”
- Most numerous T cell
- Enhances activation and proliferation of T lymphocytes, B lymphocytes, and NKC
Suppressor T Cells (Sensitized T Cell)
- “Police man”
- Inhibits T cell function by negative feedback
- Controls immune responses
Memory T Cells (Sensitized T Cell)
- Survive in lymphoid tissue and wait for a second exposure to the same antigen
- Quicker response time and greater response than initial immune response
Humoral Immunity
- Involves B cells (action takes place in the plasma)
- Also known as “antibody-mediated” immunity
- B cells transform into plasma cells and produce specific protective proteins called antibodies in response to antigen
- Antigen and antibody fit together and form a complex which activates B cells to clone itself
How do antibodies work?
- Neutralize the antigen
- Prevent attachment of pathogen to cell
- Immobilization of bacteria
- Agglutination and precipitation of antigen
- Enhance phagocytosis by other phagocytic cells
IgG Antibody
- Most common antibody
- Found in blood and extracellular fluid after prolonged exposure to antigen
- Combats bacterial and viral infections
- Can cross placental barrier to provide passive immunity to fetus
IgM Antibody
- 1st antibody made by newborns (in response to antigen)
- Provides temporary protection
IgA Antibody
- Mucosal immunity
- Blocks attachment of antigen on mucosal surfaces
IgE Antibody
-Allergic response
IgD Antibody
- Activates other cells to produce anti-microbial factors
- Hangs out on unexposed B cells and acts as a receptor
B Memory Cells
- Function the same as T memory cells
- Do not differentiate into plasma cells
- Survive in lymphoid tissue and wait for a 2nd exposure
- Creates a quicker, greater response to antigen
Passive Immunity
- Immunity produced by administration of preformed antibody
- Causes immediate but short lived immunity
- Maternal: ingestion of colostrum
- Artificial: Administration of plasma or antiserum
Active Immunity
-The body mounts an immune response to the presence of an antigen
- Recovery from natural infection
- Vaccination
Type 1- Immediate Hypersensitivity
- 20-30 minutes
- Anaphylactic reaction (histamine is released)
- C/S: redness, swelling, hives, airway obstruction
- GI: diarrhea, abdominal cramping
- Most common cause: vaccines
- Treatment: Benadryl, +/- epinephrine
Type II- Cytotoxic Hypersensitivity
- Antibodies formed against the animals own blood or tissue cells
- Autoimmune reaction
- Example: Immune mediated hemolytic anemia (IMHA)
Type III- Immune Complex
- Inflammatory reaction
- Antibodies and antigens combine to form complexes –> become trapped in endothelium
- Example: Rheumatoid arthritis
Type IV- Delayed Hypersensitivity
- Inflammatory reaction happens over time (days)
- Example: TB test, skin allergy test
Primary Lymphatic Organs
- Red bone marrow
- Thymus
Secondary Lymphatic Organs
- Lymph nodes
- Spleen
- Tonsils
- GI associated lymph tissue
Functions of the Lymphatic System
- Removal of excess interstitial fluid
- Waste material transport
- Filtration
- Protein transport
- Transportation of dietary lipids
- Protect against foreign invasion
Lymph
-Fluid carried by lymphatic system
-Contains:
Interstitial fluid
Lymphocytes (WBC)
Macrophages
Proteins
Waste
Red Bone Marrow
Produces all WBC’s
Thymus
- University of Thymus
- Located around trachea at thoracic inlet
- Prominent in young animals and regresses at puberty
- T lymphocytes are processed here before distribution into peripheral tissues
- Kicks start normal immune development
Lymphatic Vessels
- Similar to veins (thin, walled, one way valves)
- Collect excess interstitial fluid –> send through lymph nodes –> return to blood
- Stream via the thoracic duct which empties into the systematic circulation via the right atrium of the heart
Lymph Nodes
-Small, kidney bean shaped structures along length of lymphatic vessels
-Function:
Filter blood, add lymphocytes to lymph fluid
Peripheral Lymph Nodes
Submandibular ** Prescapular ** Axillary Inguinal Popliteal **
** Can be palpated
Spleen
-Largest lymph organ in the body
-Functions:
Storage of blood
Removal of foreign material by macrophages
Removal of dead, dying abnormal RBC’s by macrophages
Lymphocyte cloning during immune response
Tonsils
- Nodules of lymphoid tissue, found in epithelial tissue
- Mature lymphocytes live in tonsils
- Pharyngeal tonsils: Prevent spread of infection into the respiratory or digestive system
Differences between Tonsils and Lymph Nodes
- Tonsils are found in moist epithelial surfaces
- Tonsils do not have a capsule (LN do)
- Tonsils are found at the beginning of lymph drainage system, not along the way
Gut Associated Lymph Tissue (GALT)
- Located in lining of intestines
- Largest lymphoid organ in the body (spread out but not a true organ)
- Contains mature lymphocytes
- Ensures no bacteria escape GI tract
Dietary Lipids
-Transported by chylomicrons and are deposited into the blood stream via lymphatic vessels
Post-Prandial Lipemia
-Commonly seen if an animal has not fasted before blood work
Chyle
- Lymph from digestive system
- Contains chylomicrons after a pt. has eaten
Chylomicrons
-Microscopic particles of fat
