Chapter 13 - Immunity and Defense Flashcards
Three lines of defense
1st line of defense – skin & mucosa, etc. (physical barriers) - fort
2nd line of defense –neutrophils & macrophages (inflammatory response) - traffic cops
3rd line of defense – lymphocytes (immune response) - vaccines/security guard
Imunity
– immune reaction that helps fight
pathogens & antigens
Immune System
Immune system –
* 3 lines of defense
*Protects animal body from infection by pathogens
or antigens
Pathogens
– disease-causing organisms
*Viruses
*Bacteria
*Parasites, Fungi?
Antigens
– foreign proteins
* From pathogens
* From anything protein
* From “self” (Autoimmune diseases)
Immune system functions
Security System
Protect animal from pathogens
Recognize antigens that threaten health of animal (non-self)
Deals with
*Infectious disease control and prevention
* Cancer
*Allergies
The Immune System
Security system of the body
* Recognizes foreign material
*Protects the body from anything that is not a part of the body
Innate immune system
* First line of defense is external barriers
*Second line of defense is cellular and chemical components
Adaptive immune system
* Third line of defense is to target specific pathogens
1st line of Defense
Skin (Most visible barrier)
*Physical barrier -Covers majority of surfaces in obvious contact with environment
* Resident microorganisms
*Acidic pH and fatty acid content of sweat
Mucous membranes -barrier that lines digestive tract, respiratory tract and genitourinary tract
* Cilia and mucus in respiratory system
*Acidity of stomach
* Fluids such as tears, saliva, and urine
* Mucous protest these
surfaces from infections
Lymph from lymph nodes
Lymph flows through at least one lymph node as it
returns from peripheral limbs
* Lymph from specific areas of the body always
passes through same node(s)
* May aid in determining location of inflammatory
response, infection, or tumor
Lymph node locations
Nodes dispersed throughout body
*Submandibular
*Prescapular
*Axillary
*Inguinal
*Popliteal
MALT
Mucosa-Associated Lymphatic Tissue
Clusters of lymphoid tissue in various areas throughout the animal’s body
Located near mucosal surfaces
Not encapsulated like a lymph node
Function:
*Identify antigens
* Mount immune response
Peyer’s Patches
Aggregations of lymphoid tissue in small intestine
* Cattle, sheep, pigs, horses, dogs
Majority found in lining of ileum
* smaller percentage in jejunum
2nd line of defense
Neutrophils and Macrophages
Part of 2nd Line of Defense in animal body
Diapedesis – process used by neutrophils to go from circulation into tissue spaces
Chemotaxis – process that attracts neutrophils to inflammatory chemicals at a site of infection
Innate immune system
Innate immune system
* Rapid, nonspecific
*Present at birth
* Destroys “non-self” invaders
* Uses physical, chemical, and cellular components to protect body
* Provides anatomical and cellular barriers
* Body’s first and second lines of defense
* Does not recognize specific pathogens
Adaptive Immune System
*Slower to respond
* Not present at birth
* Targets specific organisms
* Develops and adapts as animal matures and is exposed to antigens
* Uses antibodies, memory cells, plasma cells, B lymphocytes, and T lymphocytes
External Innate Immunity
First line of defense
Anatomical barriers on surface of body
*Keratinized epithelial tissue of skin
* Mucous membranes
– Line respiratory, digestive, urinary, and reproductive systems
* Tears, saliva, and nasal discharge production
*Acidic environment of the stomach
Internal Innate Defense
Second line of defense
When a pathogen makes its way past physical barriers, the body controls spread of infection through acute inflammation
Fever
Elevated body temperature
A systemic inflammation response where chemical mediators are carried throughout the body
* Creates environment exceeding optimum temperature for growth of pathogen
Excessively high body temperature (>104°F) may cause proteins to denature
Phagocytosis- line of defense and description
Second line of defense
Several types of cells capable of phagocytosis
* Neutrophils, monocytes, macrophages, dendrite cells
Cells contain receptors on outer membrane to differentiate “self” versus “non-self”
Steps of Phagocytosis
5 Steps:
Activation and chemotaxis
Attachment
Ingestion
Destruction
Exocytosis
The Complement System
Group of 30+ plasma proteins, mostly inactive proteolytic enzymes
Always present in plasma in inactive form
Become active in presence of antigen, or an antibody attached to an antigen
Functions
* Trigger inflammation
*Alter microbial cell membranes (opsonization)
Complement cascade
When one complement protein is activated, it activates the next complement protein in the series
Final result is antigen cell lysis, or body cell apoptosis
MHC
Major histocompatibility complex (MHC)
Healthy host cells express self MHC-1
- This ensures that NK cells do not attack normal host cells
Interferons
Proteins produced in response to presence of viruses, bacteria, cancer, and other foreign invaders - innate defense
B Cells life cycle
Formed in the bone marrow
Migrate to lymph nodes and spleen
* When stimulated by presence of specific antigen
* Differentiate into plasma cells
* Responsible for actual production, storage, and release of antibodies
thymocytes
Precursors to T-cells
* Originate in red bone marrow
* Migrate to thymus to mature and multiply
Enter bloodstream as T cells
* Migrate to lymph nodes and spleen
* Coordinate cell-mediated immunity
Adaptive Immune Types
Humoral and Cell-mediated
Humoral
- Triggered by extracellular pathogens
- Results in production of immunoglobulins by B cells/plasma cells
- Targets specific antigens for destruction
Cell-Mediated
- Provides immunity against intracellular pathogens
- Does not depend upon antibody production
- T cells attach directly to antigen markers on surfaces of phagocytes that have already processed the pathogen
- Intracelleular
Humoral Physiology
Process when B cells recognize an antigen and transform into plasma cells
B-lymphocytes (B cells) transform into plasma cells
*Produce antibodies (immunoglobulins) to specific antigens -
*Stay in lymphocytes, send antibodies into bloodstream
* Memory cells
*All other B cells are unaffected
Immediate hypersensitivity
Plasma cells produce, store, and release antibodies
*Plasma cells found in any body tissue
* Most numerous in tissues engaged in antibody formation
Extracellular
Humoral (Antibody) Immunity
IgM
Immunoglobulins/Antibodies
* First Ig made during first exposure to an antigen
* The largest antibody (know this)
* Temporary
IgG
Immunoglobulins/Antibodies
* Smallest and most common
* Made when animal exposed to an antigen for a long time or when exposed to the antigen for the second time
* Indicative of a chronic infection
* Can cross the placenta, producing passive immunity to fetus
IgA
Immunoglobulins/Antibodies
* Can leave blood and enter tissue fluids
* Plays a role in protecting mucosal surfaces (e.g., intestinal tract and lungs)
IgE
Immunoglobulins/Antibodies
*Binds to allergens and triggers histamine release from mast cells and basophils
*Associated with an allergic response
*Protects against parasitic helminth infections
IgD
Immunoglobulins/Antibodies
- Activates basophils and mast cells
- Uncommon
Examples of Humoral/Antibody Immunity
Vaccines
Tetanus Toxoid injections
Cell Mediated Immunity (CMI)
Controlled by T cells
* Circulate in blood and lymph
–Does not depend on antibody production
*Programmed to attack and destroy foreign cells and diseased host cells (specific antigens)
*Produced throughout life of the animal
* Microscopic clusters of cells
* Memory cells
* Delayed hypersensitivity
Provides immunity against intracellular pathogens
T cells attach directly to antigen markers on surfaces of phagocytes that have already processed the pathogen
Examples of Cell Mediated Immunity
TB testing
Allergy testing
Fundamentals of Acquired Immunity
(3rd Line of Defense)
Naturally acquired immunity is acquisition of adaptive immunity through natural events
Immunization mimics these events by inducing artificially acquired immunity
Natural or artificial immunity can be divided into
* Active immunity
* Passive immunity (borrowed)
Active Immunity
The result of an active immune process - Antibodies made by animal
* Natural immunity – getting the disease and living (IE exposure to antigen)
*Vaccines (artificial)
– Modified live (attenuated)
—Killed virus
Long-acting
Memory cells
Examples
* Disease itself
*Vaccines
* Tetanus toxoid
Passive Immunity
Receiving antibodies from an external source ( “borrowed”)
* Maternal antibodies - (colostrum)
*Across the placenta
*Via colostrum
Offers protection
* No activation of immune system
Protection lost once antibodies disappear from the animal’s system - no memory cells
- short acting
Young animals
Creating Immunity in Animal
Biological – product of a living organism that produces immunity in an animal
*Vaccines – viruses
*Bacterins – bacteria
*Immunity not as strong
* Risk of reactions
2 Common of Antibodies Immunoglobulins
IgM – made during first exposure to antigen
*Primary response
*Slow production
IgG – made during second exposure to antigen
* Most common immunoglobulin
*Secondary (“booster”) response
*Production more rapid than IgM
* Can cross the placenta
Feline Core Vaccines
Feline Distemper (Panleukopenia)
Feline Viral Rhinotracheitis (FVR)
Feline Calici Virus
Rabies
Factors in Determining Likelihood of Disease
Exposure
Mode of infection/transmission
Virulence – relative strength of the pathogen to invade animal immune system
Immune system strength
*Young, old, immunosuppressed animals
Resistance
*Acquired resistance
*Exposure or vaccination
*Species resistance
Canine Core Vaccines
Rabies
Combo vaccine-
-distemper
-adenovirus
-parvovirus
- +/- parainfluenza
Complement protein
Produced in the liver and circulate in the blood
Function as part of the complement system (30+ plasma proteins)
- cause inflmation
- alter microbial cell membranes (opsonization)
Cytokines
Cytokines are small proteins that are crucial in controlling the growth and activity of other immune system cells and blood cells.
— found in lysosomes
Interleukins
Control leukocytes
Necessary for T cells to grow, differentiate, and activate during inflammatory and immune response
Organs involved in immunity
Spleen, lymph nodes, thymus, GALT, bone marrow
Where is MALT found
Tonsils (pharynx)
adenoids (pharynx)
Peyer’s patches (intestines),
clusters of lymphoid tissue in the gastrointestinal tract
in rabbits the appendix (intestines)
Difference between first and second line of defense
The first line of defense is composed of external barriers (skin, mucous membranes, secretions). The second line of defense is internal and activated only when the first line of defense fails.
apoptosis
cellular changes that lead to cellular death
Pros and Cons of Fever
Benefits of fever include increased rate of phagocytosis, slowed bacterial growth, and potential killing of the pathogen.
Risks include denaturing of the proteins and injury to bodily tissues and cells.
The phatocytic Cells:
All white blood cells except lymphocytes and basophils: *Neutrophils
*eosinophils
*monocytes
And tissue macrophages.
Antibodies come from:
B-Cells
Stages of differentiation for T and B cells
1) Native cells enter the lymphatic system but have not encountered an antigen.
2) Cytotoxic or effector cells activate and are involved in eliminating a pathogen.
3) Memory cells provide long-term immunity.
Three type of T cells
Helper T cells (TH) - secrete cytokines into the surrounding tissue to improve immune response.
Cytotoxic T cells (TC) - attach to the antigenic cells and destroy them.
Regulatory T cells (TS) - inhibit helper T cell and cytotoxic T cell function by negative feedback. They also prevent B cells from transforming into plasma cells.
Hypersensitivity Reactions
Type 1- severe: anaphylactic shock, atopic dermatitis, food allergies
Type 2 - Infection is present - immune system cause of disease
Type 3- Immune complex: antibody and antigen form immune complexes - Example is lupus
Type 4- Cell-mediated reactions
Factors determining likelihood of disease
Exposure
Mode of infection/transmission
Virulence of the pathogen and degree of pathogenicity
Immune system strength
Resistance
lipemia
Lipemia is presence of a high concentration of lipids (or fats) in the blood. It can be caused by the presence of fat from digested food in the sample (postprandial)
Why fasting before blood samples is desired
pathogen-associated molecular patterns
PAMP
Common molecules found on the membranes of pathogens and shared by large groups of pathogens
pathogen recognition receptors
receptors on macrphages or dendridic cells that bind to pathogen-associated molecular patterns
Primary lymphatic System
- Thymus
*Bursa of Fabricius (Avian)
*Peyer’s patches - Intestinal tract
histamine
Produced by mast cells from histidine during tissue injury
- Part of inflammation. -
Mast Cells
Transient cell of connective tissue
- releases heparin and histamine into foreign invaders
Resemble basophils
Do not circulate in blood
B cells
Lymphocytes
travel through lymph nodes, spleen and other lymphoid structures
-rarely in peripheral blood
Responsible for humoral immunity
Each B cell produces one specific antibody against one antigen
T cells
Lymphocytes
Processed in thymus and then go to peripheral lymphoid tissue
Responsible for Cell mediated immunity
- no antibodies involved
Activate B cells
