Download The One and Only… The Famous… IMMUNE SYSTEM!!!!

The One and Only…
The Famous…
IMMUNE
SYSTEM!!!!
What is Immune
System and what
is the Purpose of
it?
• The immune system…
– is the major part of the body’s defenses.
– is a specific defense that responds to the
particular substances (cells, toxins, and
proteins), that are known to be foreign material
to the body, therefore making them unwanted.
– Is intended to recognize and remove unwanted
material.
The Immune
Response
• The unique antigens on the surface of an
individuals cells can distinguish “self” from
“non-self” (foreign substances) and can detect
and destroy the unknown material.
• The immune system…
– ignores the “self” cells which demonstrates
tolerance.
– can recognize an invader antigen as
foreign, develop a specific response to that
particular antigen, and then stores that
response in the memory cells for future
reference if incase the antigen returns.
– Is assisted by general defense mechanisms
(phagocytosis and the inflammatory
response) to destroy foreign material.
• By removing the foreign material, the
immune system plays a role in preparing
injured tissue for healing.
– When the membrane of a malignant neoplastic
cell is abnormal, the immune system might be
able to identify these cells as foreign and
remove them which leads to the prevention of
cancer.
– Unfortunately, not all cancer cells are defined
as foreign causing them not to be removed from
the system.
Components of the
Immune System
• It consists of lymphoid
structures, immune cells,
and tissues concerned with
immune cell development.
• The basic structures where
immune response can
function are the lymph
nodes, spleen, tonsils,
intestinal lymphoid tissue
and lymphatic circulation.
A
n
t
i
g
e
n
s
• also known as immunogens
• can either be foreign substances or human cell surface
antigens which are very unique.
• Complex proteins or polysaccharides, or even a
combination of them known as glycoproteins compose
most antigens.
• provoke the body's immune system to produce antibodies
that match the antigens to latch on and destroy them.
• Antibodies- specific protein produced in
humoral response to bind with antigen.
• Autoantibody- antibodies against self antigen
that attack own body's tissues.
• Lymphatic tissue- contains many leukocytes;
filters body fluids, removes foreign matter,
immune response.
• Bone marrow-source of stem cells, leukocytes.
• Thymus- site of maturation and proliferation
of T lymphocytes
• The antigens are present on an individual's cell membranes.
• They are coded by genes that are inherited from the parents
(called major histocompatibility complex-MHC).
– It is unlikey that two individuals would ever have
identical antigens because since theyre inherited from the
parents, they can make a large number of combination
groups of genes.
• MHC - activates and regulates immune response and
intercellular communications.
– These molecules detect changes in cell membranes
caused by viruses or cancer.
– Basically, If someone has a virus or something that is
changing the cell, the MHC recognizes it and alters the
immune system in response to the change.
• Human MHC
– also known as Human Leukocyte Antigen
– provide close match for tissue transplantation>immune
system activated by different MHC molecules>then it can
tolerate self antigens and its not foreign so they dont
attack.
Cells…
• Macrophages…
– large phagocytic cells that intercept and engulf
foreign material and then process and present the
antigens from the foreign material to the
lymphocytes thus initiating the immune response.
– developed from monocytes which are part of the
mononuclear phagocytic system, or
reticuloendothelia system.
– Secrete monokines and interleukins that play a
role in activation in additional lymphocytes and in
the inflammation response (secondary immune
response).
Lymphocytes…
• white blood cell
– primary cell in the immune response
– produced by the bone marrow
– known as immunocompetent cells when matured
(cells who have special functions in recognizing and
reacting with antigens)
• two kinds t-cells
– T-cells (cell-mediated immunity)
– B-cells (humoral immunity)
T-Cells
– arise from stem cells in the bone marrow (process
shown in chart)
• Cell-mediated immunity- t-cells with protein
receptors on cell surface recognize antigens on the
surface of target cells and directly destroy the
invading antigen – then they reproduce to create
an army to battle the invader (also activate other
lymphocytes both t and b), primarily affective
against virus-infected calls, fungal, and protozoal
infections, cancer cells, and foreign cells.
• CD8 (cytotoxic) positive t-killer cells – destroy target by
binding to antigen and releasing damaging enzymes
(destroy target and cause inflammatory response)
• CD4 (helper) positive t-cell – facilitates immune
response, regulate all the cells in the immune system (b
cells, t cells, macrophages, and natural killer [NK] cells,
by secreting messenger cytokines)
• Memory t-cells- remembers invader to activate response
again if returned
• B-cells – responsible for humoral immunity thorugh
production of antibodies or immunoglobins. Brought to
the spleen and lymphoid tissue once matured. Become
antibody producing plasma cells with help from t-cells
and after expose to antigens- act primarily against
bacteria and viruses that are outside body
• Natural killer – lymphocytes that destroy without prior
exposure and sensitization, tumor cells and cells infected
with viruses.
Antibodies/Immunoglobulins…
• An antibody is a protein complex used by the immune
system to identify and neutralize foreign objects like
bacteria and viruses.
• Each antibody recognizes a specific antigen unique to its
target.
• Antibodies are found in the general circulation, forming
the globulin portion of the plasma proteins, as well as in
lymphoid structures.
• Antibodies that recognize viruses can block directly by
their sheer size.
• The virus will be unable to dock to a cell and infect it,
hindered by the antibody.
• Antibodies that recognize bacteria mark them for ingestion
by macrophages.
• Together with the plasma component complement,
antibodies can kill bacteria directly.
• a system of proteins in the bloodstream
which works in an organized fashion to
defend against infecting pathogens.
• These proteins work with the
antibodies and phagocytes to rid the
body of infection.
• Complement activation also initiates an
inflammatory response.
• Complement – group of inactive proteins in the circulation that,
when activated, stimulate that release of other chemical mediators
(promote inflammation, chemotaxis , and phagocytosis).
• Histamine – released from mast calls and basophils, particulary in
allgeric reactions, cause vasodilatation.
• Kinins – cause vasodilatation, and pain.
• Leukotrienes – groups of lipids, derived from mast cells and
basophils, cause contraction of bronchiolar and inflammation.
• Prostaglandins – group of lipids; varied effects: inflammation,
vasodilatation, and pain.
• Cytokines (messengers) – stimulate activation and proliferation of b
and t cells, communication b/w cells – involved in fever and
leukocytosis.
• Tumor necrosis factor (TNF) active in inflammatory anf immune
response; stimulates fever, chemotaxis, mediator of tissue wasting,
stimulates t cells, mediator in septic shock (decreasing BP)
stimulates necrosis in some tumors.
• Chemotactic factors – attract phagocytes to area of inflammation.
Diagnostic Tests…
• Tests asses the levels and functional qualities
(qualitative and quantitative) of serum
immunoglobulins or the measure of specific
antibodies.
– Identification of the antibodies are required for
detecting Rh blood incompatibility or to screen for
HIV infection.
– Pregnant women are checked for levels of antibodies,
especially for German measles.
– During a hepatitis B infection, the levels of antigens
and antibodies change which helps monitor the course
of the infection.
Diagnostic Tests cont…
• The number and
characteristics of the
lymphocytes in the
circulation can also be
examined.
• Extensive HLA typing is
required to complete
tissue matching prior to
transplant procedures.
The Process
of
Acquiring
Immunity
Immune Response
1. Primary response- when 1st exposed to an antigen: during exposure
antigen is recognized and processed: development of antibodies or
sanitized T lymphocytes is initiated.
2. Secondary response- repeat exposure to the same antigen: memory
cells stimulate production of antibodies or T cells
•
As one ages the number of infections declines
•
When there are many strains of bacteria or virus causing a disease, an
individual never develops antibodies to all the organisms.
•
Influenza- have several antigenic forms: have strains that mutate or
change slightly over time: new vaccines each year.
Active Immunity- when a persons own
body develops antibodies or T cells. Takes
a few weeks but lasts for years.
Passive Immunity- Antibodies are
transferred from 1 person to another.
Effective immediately but only temporary
protection.
How is immunity acquired?
Memory
Natural
Active
Pathogens enter body and
causes illness; antibodies
form in host
Vaccine is injected into
Artificia
l Active person. No illness results but
Yes
Person has
chickenpox
once
Yes
Person has
measles vaccine
and gains
immunity
No
Placental passage
during pregnancy
or indigestion of
breast milk.
No
Gammaglobulin
if recent
exposure to
microbe
antibodies form
Natural
passive
Antibodies passed directly
from mother to child to
provide temporary
protection
Artificia Antibodies injected into a
l Passive person to provide temporary
protection to minimize
severity of infection
• Toxoid- an altered or weakened bacterial
toxin that acts as an antigen in a similar
manner
• Booster- an additional immunization given
perhaps 5 or 10 years after the initial
immunization that reminds the immune
system of the antigen and promotes a better
secondary response.
Questions
1. Differentiate between active and passive immunity?
2. Name 3 Chemical Mediators?
3. What is the immune response?
4. What is another name for antigens?
5. What are the four ways immunity is acquired?