Transcript Immunity PP - TeacherWeb

IMMUNITY
Dr. L. Rueda
CUHS
 I. The lymph is a circulatory system with
many functions
A. Lymph vessels surround blood vessels
1. One cell thick
2. Fluid is similar to blood, but compatible
with fat solubles
3. Has no ‘pump’ ( no heart), operates by
muscle contractions and gravity
* Edema ( tissue swelling) of bedridden
patients is apt to be due to this system not
working correctly
4. Backflow is prevented by valves
B. Operation
1. Lymph vessels are net like (more permeable
than blood vessels). 2.Collect excess fluid
from tissues and dump into heart
3. Fluid is recycled through circulatory system
C. Functions
1. Pick up fluid and waste
2. Nodes of the lymph produce
antibodies ( lymphocytes ) necessary to
fight infection. These circle through
lymph and blood
* During infection, lymph nodes swell
as WBC fight it
II. Immunity: reaction of the body to foreign
agents (microbes, parasites,
chemicals,
cancer). Takes four forms:
A. Natural : immunity that the body makes
on its own, innate
B. Acquired: immunity after exposure to an
antigen, or, vaccine
C. Nonspecific: does not target specific
organisms
D. Specific: antibody, or protein, response to
specific targets
II. Nonspecific immunity
A. Physiological barriers: skin and mucous
membranes act as barrier
1. Skin has pH of 3 to 5, impermeable to
bacteria and virus
*Oil and sweat give lowered pH
2. Mucous, saliva, tears can wash away
bacteria
* Contain lysozyme
3. Nostrils filter pollen
4. Stomach acid kills bacteria
B. Phagocytic immune cells target microbes,
dead cells
1. Phagocytes are cells that eat other cells or
invading objects
2. Neutrophils (70% WBC) move like
amoeba, surround and kill bacteria, Then they
themselves die.
3. Monocytes (5%WBC) become
macrophages, large amoeboids
Their enzymes and reactive oxygen break
down bacteria, dead neutrophils, dead RBC’s
4. Eosinophils: (2%WBC) attack parasitic
worms
C. Molecules in the blood, proteins, do not
‘kill’ invaders, but limit their
reproduction
1. Interferons are proteins made by virus
infected cells. They
*Are a form of ‘self-vaccination’. They
migrate to adjacent cells and cause them to
have an immune response.
*Attack viruses, and are nonspecific. Have
a short term effect
*We are mass producing them (DNA tech)
as cold vaccines
D. Certain cells produce chemicals called
cytokinens, which breakdown microbes.
Similar to interferons
E. The inflammatory response to cuts is
nonspecific
1. Open wounds harbor bacteria. To kill
bacteria, they need WBC’s
2. To get WBC’s, we need extra blood flow
so...
3. Basophils in the blood release histamine
causing vasodilation
4. Dilated capillaries are leakier
5. Redness is due to increased capillary blood
flow
6. Swelling is due to increased permeability of
blood vessels
allowing WBC’s to migrate into the tissues
*Neutrophils come first, they die
*Macrophages come an finish the job, and
digest the waste
* Clotting proteins seal off the area
III. Specific immunity: antibodies/proteins
produced by B and T cells.
A. Terminology
1. Immune response; a recognition system
which distinguishes between self and nonself
2. Antigen-foreign substance
3. Antibody- a specific defense protein which
helps to control antigens from damaging the
body
4. Immunity- protection afforded to a body by
previous exposure to an antigen
5. Active immunity- with encounter to an
actual virus or bacteria
body is producing antibody
6. Passive immunity- temporary acquired
antibodies passed on to organism ( vaccine)
B. Antigens are generally foreign particles
invading the system
1. Antigens each have a specific conformation
2. This shape is recognized by the
antibody/protein
3. Are large proteins or polysaccharides,
contain an active site known as an epitope.
4. Two types of immunity cells are made in
the bone marrow
* B cells-secrete antibodies , extracellular
* T cells- function within cell
C. Humoral Immunity: the body fluids contain
B cells which make antibodies. Found in
blood and lymph
1. Fights toxins, bacteria, viruses
2. B cells form in the bone marrow and
mature at the lymph nodes.
3. Become activated in presence of antigen
* Form effector cells-->plasma cells-->
secrete antibodies
4. Antibodies are specialized proteins:
immunoglobulins (Ig)
* Are Y shaped. The Constant, or ‘C’ area is
the stem
* The Branched ‘V’ top is variable
* Act by binding to antigen and either
changing its shape or
Causing it to agglutinate (clump-blood
cells)
C. Humoral Immunity: the body fluids contain
B cells which make antibodies. Found in
blood and lymph
1. Fights toxins, bacteria, viruses
2. B cells form in the thymus, but mature in
the bone
3. Become activated in presence of antigen
* Form effector cells-->plasma cells-->
secrete antibodies
 4. Antibodies are specialized proteins:
immunoglobulins (Ig)
 * Are Y shaped. The Constant, or ‘C’ area
is the stem
 * The Branched ‘V’ top is variable
 * Act by binding to antigen and either
changing its shape or
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Causing it to agglutinate (clump-blood
cells)
 5. Occurs mainly in lymph nodes
• 6. Targets extracellular invaders, ie those circulating
in the blood stream, tissues, spleen, and lymph .
Causes invaders to:
 * Be neutralized- surround it so that
phagocytes can then eat it
–
* Agglutinate- bind together many antigens so that
phagocytes can eat
 * Precipitate:similar to agglutination
 C. Cell mediated immunity: intracellular
phagocytosis, by T cells
• 1. Once pathogens invade the body’s cells, pass cell
membranes, they are harder to target
–
*Recognize this type of invader through the MHC
(major histocompatability complex, a group of proteins
unique to each human, to each cell)
 * T cells recognize the normal MHC
composition of cell membranes. Red flag
when a ‘foreign’ component shows up
 2. T and B cells start out in the bone marrow. T cells must
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travel
through the thymus to mature
2. T cells have three forms
* Cytotoxic T’s : kill invaders expressing foreign
antigens
produce chemical toxin- perforin. Attack cancer and
viruses
• *Helper T cells: produce cytokines, chemicals
which bind to membranes of foreign substances,
alter its composition, digest it
* Suppressor T cells- inhibit the activity of other t-cells
these are necessary for feedback inhibition
 D. Autoimmunity: We must be able to
recognize ALL the chemicals, enzymes
and proteins in our own bodies. MHC does
this
 1. Major histocompatability complex: 40
enzymes/proteins that
recognize
organs/tissues. Only alike in identical twins
 2. Cyclosporin: suppresses this response,
but allows some humoral
immunity.
This facilitates organ transplants
 IV. Immune response is a two stage process:
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A. Primary response: first contact either with the disease,
or vaccine
1. Vaccines can be dead or heat weakened cells, or inactive
bacterial toxins
2. The lymphocytes create ‘clone cells’ which begin to
produce the
antibody, or T cell product.
3. Takes 5-10 days for maximum production (Rh factor- 2
months)
B. Secondary immune response. The next encounter is
swift. Can be
several minutes to 5 days to fight
invader
1. Each response will be stronger
2. An allergic reaction can occur id body ‘over-reacts’
 V. Immune system diseases
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A. Autoimmune diseases: flaws in MHC, lupus
(skin and internal organs get scarring), rheumatoid
arthritis, insulin dependent diabetes( self attacks
pancreas destroys cells). Graves (thyroid)
• 1. Lupus; body directs WBC towards own tissues.
Causes inflammation and injury
* Attacks: skin, kidneys, muscles, lungs, heart, blood
*Attacks women 8-10 times more then men
*Disease cycles, and varies in devastation
* Fever, rash, weight loss are initial symptoms
• *advanced lupus- causes skin pulling, tight, lesions,
destroys organs with scarring
• B. Allergy: an oversensitive immune system reacts
to an otherwise harmless substance (called
allergens).
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1. Specific antibody (E or IgE) made.
 2. This antibody causes excess histamine to
be released
 C. Anaphylactic shock: acute allergic
response.
 1.Histamine production is excessive.
 2. Blood vessels dilate so rapidly that blood
pressure drops.
 3. Can be fatal in 3-5 minutes. Three main
causes: peanuts,
shellfish, bee stings.
 D. Immunodeficiency: general inability to fight invaders
 1. SDID: rare genetic disorder, ‘bubble’ kids, live in space
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suits
are know treating with bone marrow transplants (immune
system cells are made in the marrow)
2. Lymph cancer- immune cells reproduce uncontrollably
Leukemia, and Hodgkin’s disease
3. HIV - AIDS- reduced Th cell count, suppresses both H
and T cells
*Don’t die of AID’s , but of a 20 infection
*HIV is provirus, attaches to CDH receptor complex to
enter cell
* USA: drugs/homosex. Africa: heterosex/
nursing/hygiene
 VI. Immune response depends on age,
health, particular antigen
 A. Age- immunity is enhanced by aging,
to a point
 1. Develop more b cell responses
• 2. Babies get through mother’s early milk (
colostrum), one of main benefits of nursing.
• * Babies treat foods as antigens . Must allow
immune system to develop before food is given
 * When first given food, introduce one food
every two weeks, allowing body to adjust
 B. Heredity-genes determine your ‘self’
markers
 VII. Current treatments are in the infancy stages
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A. Recombinant DNA technology- developing
appropriate antibodies
1. Being used for rheumatoid arthritis
• B. Organ transplant- necessary for other reasons,
but susceptible to rejection as the MHC is different
in every person, even twins
1. Treat with drugs
2. Using DNA technology to infuse ‘self’ into donated
tissue
C. Vaccines for retroviruses (AIDS) and certain cancers
D. Treatment with a man made ‘t-cell’ chemicalinterleukin-2
E. Cloned B cells (man made antibodies- monoclonal
antibodies)