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77 terms

Immune System - 3rd Line of Defense

components of 3rd line of defense immune disorders
3rd Line of Defense
1. specific immunity or immune system proper
2. identifies and destroys foreign materials
2 Features of 3rd Line of defense
1. Specificity
2. Memory
Specificity of 3rd Line of Defense
1. response to particular pathogen
2. developing specific antibody to virus - that doesn't expand to other pathogens but there is a little overlap with cells of similar nature
Memory of 3rd Line of Defense
1. once there is an initial exposure, cells will recognize pathogen during re-exposure and not cause an issue
Ways 3rd Line Attacks Pathogens
1. Cellular Immunity
2. Humoral Immunity
Cellular Immunity
T cells directly go after foreign cells, cancer cells, diseased host cells, parasitic worms, and transplant tissue
Recognition of Cellular Immunity
1. APC identifies Ag of enemy cell, takes it in and displays it's epitopes on the surface
2. APC travels to lymphatic tissue and displays epitopes to T cells.
3. T Cell attaches to APC at the MHC - ↑ in MHC's help to identify foreign cells
4. T cell will modify to combat particular pathogen
5. When id is complete, rapid mitosis will occur to fight Ag
6. Some T cells will also be used for memory
Attack in Cellular Immunity
1. T cells differentiate to Th cells and Tc cells
T helper cells (Th cells)
when they identify they secrete interleukins - attracts macrophages, NK cells, and neutrophils
Cytoxic T Cells (Tc Cells)
1. attacks pathogen directly
2. attaches to enemy surface and delivers lethal hit of toxic chemicals
3. kills enemy cells one at a time
4. peak efficiency lasts a week then it declines
Examples of toxic chemicals released by Tc Cells
1. perforins
2. Interferons
3. Granzymes
4. Tumor Necrosis Factor
Tumor Necrosis Factor
specifically attacks cancer cells
Memory in Cellular Immunity
- Tm Cells retain the ability to combat the particular enemy if there is a re-exposure
- in 2nd attack, Tm cells will initiate a T cell Recall Response
- Benefit: kills off enemy cells before signs occur
cell Recall Response
causes Tm cells to undergo rapid mitosis and differentiate into Th cells and Tc cells
Humoral Immunity
1. mediation by antibodies
2. neutralizes or tags pathogens for destruction by mechanisms in 2nd line of defense
3. works on extracellular bacteria, yeasts, protozoans, viruses, and chemical pathogens like poisons, venoms, and allergies
Recognition of Humoral Immnunity
1. occurs when Ag binds to B cell
2. B cells digest anitgen, displaying it's epitope
3. Epitope will alert B cells to recognize Ag
4. Th cells also stimulate mitosis of B cells
5. Cloned B cells will differentiate to Plasma Cells
6. Plasma cells take up residence in lymphatic tissue
7. plasma cells will begin to produce antibodies about 2000/sec until they die
8. B cells will also differentiate into Bm Cells
Attack of Humoral Immunity
- occurs in 4 ways
- ab response typically takes from 3-6 days, most is spent of B cells differentiating
Antibodies (Ab)
1. proteins or gamma globulins
2. found mostly in body secretion
3. circulate in blood plasma and enter in tissue
4. Line in specific membrane
5. diverse range of proteins in every Ab
How are there so many varieties of antibodies
1. Somatic Hypermutation
2. Somatic Recombination
Somatic Hypermutation
B cells mutate more rapidly than any other cells. Rapid mutation = greater flexibility to adapt to evolving pathogens
Somatic Recombination
B cells can shuffle portions of DNA, mix and match them to build new genes to combat pathogens
4 Ways to attack in Humoral Immunity
1. Neutralization
2. Complement Fixation
3. Agglutination
4. Precipitation
antibody binds to pathogenic regions of pathogen, covers pathogenic part, rendering it harmless
ie) typically done on viruses
Complement Fixation
- ab goes after enemy cell by attaching itself to enemy and produces a binding site for complement proteins
- to initiate a 2nd line of defense response
- Ab causes enemy factors to stick together which immobilizes Ag so it doesn't spread and then 2nd line of defense mechanisms can come to take care of it
creates Antigen-Antibody complexes that attaches antigen to antibody and is removed through immune clearance.
Memory in Humoral Immunity
1. ↑ Ab Titer (Ab in the blood) - occurs while fighting pathogen
2. remains elevated for months afterwards - mechanism to prevent reinfections
3. Bm cells reside in lymphatic tissue
4. Initiates Amnestic Response during re-exposure
5. Ab Titer will remain elevated for years after re-exposure
Amnestic Response
- plasma cells differentiate, and antibodies increase
- strongest immune response of the body
What type of pathogen will initiate both humoral and cellular immune responses?
4 Types of Immunity that results in Resistance
1. Natural Active Immunity
2. Artificial Active Immunity
3. Natural Passive Immunity
4. Artificial Passive Immunity
Natural Active Immunity
1. most common form - uses humoral and cellular immunity
2. makes antibodies or immune cells following natural exposure to antigens within nature
Antigens (Ag)
1. any molecules that triggers an immune response
2. 2 categories
3. Unique to each individual, distinct
4. Biologically closest to relatives
5. Strong trend to attack in individuals that have the opposite antigens
6. Made of big proteins
Free Molecules of Ag
not associated with a cell i.e.) snake poisons
Cellular Antigens
protein molecules that are found on surface of cells
Major Histocompatibility Complex (MHC)
- groups of genes that aid in recognition of foreign cells
- allows the ability for indiviuals to be attracted to others with diffferent MHCs
ii. Mechanism for natural selection
iii. Allows the body to acquire more antibodies
Self vs Non-Self Response
- basic immune response
- Used to test antigens
- Your body recognizes antigen as
Self - your own antigens
Non-self - not your own antigen which causes autoimmune diseases, rejection of transplant tissue
- are small molecules that cannot be recognized as antigens
a. Problematic when they bind to another molecule and is recognized as foreign
b. Highly individualized responses
c. Body will not recognize Hapten as your self antigen
d. Body will mount an immune response
i. Basis of allergic responses like chemical allergies, dander
Three Types of Cells in Natural Active Immunity
i. NK cells
ii. T-cells
iii. B-cells
1. B cells and T cells formed immaturely in red bone marrow
2. Travels to thymus and become
able to recognize non-self antigens
How to Test Immunocompetence
1. Lymphocyte is directed to self antigen
2. If Lymphocyte ignores self antigen or attacks it, then lymphocyte will undergo Negative Selection
3. Test is necessary for self tolerance and prevents attack of your own body
4. Only 2% become immunocompetent
Negative Selection
will undergo anergy (inactivation) or clonal deletion - destruction of cells
Positive Selection
lymphocytes are cloned in the thymus to colonize lymphatic tissues and organs
b. T Cells will need an APC to identify pathogens
c. B cells do not
Artificial Active Immunity
1. inject Antigen into the body so your body will learn how to fight it.
I.e.) Vaccine - pre-exposing your body to pathogen before you get it.
Natural Passive Immunity
1. temporary acquisition of antibodies from another person
I.e.) either placental transfer or breast feeding, mother will transfer antibodies to baby to build up into system
Artificial Passive Immunity
1. temporary acquisition of antibody by blood transfusion or blood serum injection
2. Used for boosting vaccines like Hepatitis B and immunoglobulins
I.e.) Treats for snake bites, anti-venom
iii. Used for Tetanus, rabies, and botulism
How is antivenom created?
is created by injecting a small amount of venom into a horse so that it can build up immunity, extract their blood, centrifuge it, and inject it blood serum into the body.
1. overactive Immunity
2. Excessive and harmful immune response typically to a pathogen most people can tolerate
Forms of Hypersenitivity
1. Alloimmunity
2. Autoimmunity
3. Allergies
Commonalities in Autoimmunity
1. Produces autoantibodies - antibodies that fight against the self tissue
2. Strike without warning or reason
Causes of Autoimmunity diseases
1. Abnormal exposure of maturing antigens in blood
2. Due to dysfunction of Blood-Thymus Barrier (Reticular Cells)
Cross Reactivity
1. occurs when non-self antigens resembles self antigens
2. Antibody created to target non-self antigens will also target self-antigens results in damage to healthy tissues
Rheumatic Fever
1. has antigens similar to antigens on heart tissue
2. Antibody created for rheumatic fever will also damage tissues to the heart
Types of Hypersensitivity
1. Type I - Acute Hypersensitivity
2. Type II - Antibody Dependent Cytoxic Hypersensitivity
3. Type III - Immune Complex Hypersensitivity
4. Type IV - Delayed Hypersensitivity
Type 1 Acute Hypersensitivity
a. Common in allergies like food, pollen, asthma
c. Is inherited condition
d. Comes and goes
e. Occurs within seconds of exposure
f. Subside within 30 min.
g. Can also be fatal
h. Allergens will bind onto basophils and mast cells
most common in children
i. Causes inflammation of the lungs, causes decrease in oxygen
ii. Triggers can vary from weather, pollen, exercise, emotional stress
Typical Type I Responses
i. Inflammation
ii. Vasodilation of tissue
iii. Smooth muscle spasm - like sneezing
iv. Increased capillary permeability - responsible for symptoms like edema, mucus secretion, watery eyes, vomit diarrhea, and hives
- severe form of Type I Hypersensitivity
- causes Anaphylatic Shock
Anaphylactic Shock
broncho constriction, systematic vasodilation, decrease in BP, circulatory shock, death
i. Epinephrine can be used to relieve the shock
Type II - Antibody Dependent Cytoxic Hypersensitivity
a. Antibodies attack cell surface of antigen
b. Results in lysis of cells in your own body
c. Occurs in tissue rejection, transfusion reaction to wrong blood types
d. Can occur in some drug reactions - which will cause death to cells quickly
e. In some reactions, antibody binds to antigen on cell surface, suppresses the cell or over stimulates the cell
Myasthenia Gravis
muscular disorder in which antibodies inhibit normal muscular activity
1. I.e.) slack face
Toxic Goiter
1. excess swelling of thyroid gland by antibody response
2. Iodine deficiency causes a toxic goiter
3. Caused by Hyperthyroidism
Type III - Immune COmplex Hypersensitivity
1. Antigen-antibody complexes become trapped beneath endothelium in CT
2. Problems that can occur are Intense inflammation and Destruction of infected tissue
3. Common in autoimmune diseases
1. systematic inflammation of Connective Tissue
2. Causes pain all over especially joints, skin lesions, sensitivity to light, persistent fever and fatigue eventually leading to weight loss, and kidney failure
Type IV - Delayed Hypersensitivity
a. Initiated by T cell response
b. Antigen response occurs after 12-20 hours after exposure
c. Chemical allergies cause this reaction like poison ivy, cosmetics, detergents, graft rejections
d. Occurs in type I diabetes which attack beta cells and decrease production of insulin
What type of test is an example of Type IV Hypersensitivity?
TB Tests
Common Factors associated with Hypoimmunodecificiences
i. Malnutrition
ii. Lack of sleep
iii. Emotional stress
iv. Age
v. Lack of exercise
Immunodecificiency Disorders
1. failure of immune system to combat pathogens
1. Severe Combined Immunodeficient Disease
2. genetic recessive disorder
3. inidividuals lacks deficiency or absense of lymphocytes
4. individual is required to live in a sterile environment
ie) bubble boy
Are there ways to cure SCID?
- gene therapy where they replace your bad genes with good ones, by inserting a good gene
- done with viruses
1. Severe depression of immune system
2. caused by HIV
3. Activation brings on flu like symptoms and becomes pronounced as immunity decreases
4. TH Cell count is less than 200/uL of blood, whereas normal healthy adults its 600-1200 cells/uL of blood
5. People with aids will die from secondary infections
Human Immunodeficiency Virus (HIV)
1. virus attacks Th cells, macrophages, and dentritic cells
2. has a long period of latency - symptoms may not show for a min. 90 days to 12 years after exposure
3. Some people have a genetic resistance to HIV and infection did not occur
4. Transmitted by blood, semen, vaginal secretions, and breast milk
5. Chimps and humans are the only organisms susceptible to HIV
6. HIV will die within minutes if air born
Reasons why HIV has a long period of Latency
1. variations in strain
2. retrovirus
3. hard to vaccinate
Characteristics of Passive Immunity
1. includes Natural and Artificial passive immunities
2. temporary - lasting a few weeks
3. received them from others
Characteristics of Acvtive Immunity
1. includes Natural and Artificial active immunities
2. persist for dacades - usually lifelong
tissue rejection in transplants
abnormal response to environmental antigens (allergens)
abnormal responses to self cells