Download Immunology Immune Response

Figure 14.1
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
Immunology: the study of all features of the body’s second
and third lines of defense
Healthy functioning immune system is responsible for:
◦ Surveillance of the body
◦ Recognition of foreign material
◦ Destruction of entities deemed to be foreign
White blood cells must distinguish self from
nonself cells
Evaluates cells by examining markers on their
surfaces
Figure 14.4
White blood cells
◦ B lymphocytes
◦ T lymphocytes
Anything that is foreign to the
body (non self) and will elicit
an immune response.
ie. an infectious agent
A group of serum proteins
whose function is to attack
and inactivate non-self
entities.
Two types of Immune
Responses
Cell Mediated
Humoral
Figure 15.4
 The cells and cell
fragments in plasma are
called formed elements
 Three types of formed
elements
 Erythrocytes – carry
oxygen and carbon dioxide
in the blood
 Platelets – involved in
blood clotting
 Leukocytes – involved in
defending the body against
invaders
 Divided into
granulocytes and
agranulocytes
T lymphocytes
There are a variety of
different immune cells
whose functions are to
recognize, tag/label,
and inactivate non-self:
◦ T helper
◦ T cytolytic
◦ T suppressor
The most important
component of the immune
system is the T helper cells.
They wander around body as
sentinels, looking for things
that aren’t supposed to be
there.
When they find something
they alert the cytolytic cells to
destroy.

T lymphocytes (cell mediated)



T-helper (recognition)
T-cytolytic (inactivation)
T-supressor (regulation and
modification of cell mediated
immune response)
 Granulocytes
 Contain large granules that
stain different colors based
on the dye used
 Three types
 Basophils – stain blue
with the basic dye
methylene blue
 Eosinophils – stain
red/orange with the
acidic dye eosin
 Neutrophils – stain lilac
with a mixture of acidic
and basic dyes
 Granulocytes
 Neutrophils and
eosinophils can
phagocytize pathogens
 Neutrophils and
eosinophils are capable of
diapedesis
◦ Defensive blood cells:
leukocytes
 Lab analysis of leukocytes
 The differential white
blood cell count test can
signal signs of disease
 Increased eosinophils
can indicate allergies or
parasitic worm infection
 Bacterial diseases often
show increase in
leukocytes and in
neutrophils
 Viral infections show
increase in lymphocytes
◦ Can be divided into five
stages
 Chemotaxis
 Adherence
 Ingestion
 Killing
 Elimination
Killing by eosinophils
Mainly attack parasitic
helminths (worms) by
attaching to their surface
Secrete toxins that weaken
or kill the helminth
Eosinophilia, or elevated
eosinophil levels, is often
indicative of a helminth
infestation
◦ Killing by neutrophils
 Produce chemicals that kill
nearby invaders
 Generate extracellular
fibers called neutrophil
extracellular traps (NETs)
that bind to and kill
bacteria
[INSERT FIGURE: 15.7]
Complement
 Activation of complement
 Body’s own cells withstand
complement cascade
 Membrane-bound
proteins on many cells
bind with and break
down activated
complement proteins
[INSERT FIGURE: 15.11]
•
•
Set of genes that codes for
human cell receptors
Gives rise to a series of
glycoproteins (MHC molecules)
found on all cells except red
blood cells
– Class I genes- code for
markers that display unique
characteristics of self
Cytokines are critical to the
development and functioning of both
the innate and adaptive immune
response, although not limited to just
the immune system.
They are often secreted by immune
cells that have encountered a
pathogen, thereby activating and
recruiting further immune cells to
increase the system's response to the
pathogen.
Role of Beta lymphocytes
Formed in response to a
foreign entity in the
body.
Antibodies formed
against toxins, bacteria,
viruses, and fungi.
Beta lymphocytes
produce/secrete plasma cells
which make immunoglobulins
aka – antibodies
5 different classes of antibodies
◦ Ig μ – Mu
◦ Ig G - Gamma
◦ Ig E – Epsilon
◦ Ig A – Alpha
◦ Ig D – Delta
Structure is normally pentameric.
This is considered to be the largest of all the antibody molecules and accounts
for about 5-10% of the immunoglobulin pool. Located in the blood, lymph, and
on B cell surfaces, these are the first antibodies to be produced in the first few
days of a primary immune response to an infecting organism. IgM antibodies
are effective against microbes and agglutinating antigens. As a consequence of
its structure, IgM is also a good agglutinator (combiner) and can clump
microorganisms together for eventual elimination from the body.
Microbiology and Immunology Online.
http://pathmicro.med.sc.edu/mayer/IgStruct2000.htm (Accessed on July 22,
2007)
IgG (structure is monomeric)
IgG is the smallest and most predominant immunoglobulin of internal
components such as blood, cerebrospinal fluid, and peritoneal fluid.
IgG makes up 80% of the total immunoglobulins and is considered the
most versatile due to its capacity for carrying out the same functions
as other immunoglobulin molecules.
IgG is the only class of immunoglobulin that crosses the placenta
conferring the mother's immunity on the fetus.
Capable of diffusing into the interstitial fluid due to its very small
molecular weight, it enhances phagocytosis, neutralizes toxins and
viruses, and protects the fetus and newborn
IgA (structure can be mono- or dimeric)
IgA represents 10 to 15% of the total circulatory immunoglobulin pool.
IgA predominates in body secretions and is mainly concerned with
defending the exposed external surfaces of the body.
It is found in the secretions of saliva, tears, nasal fluids, colostrums
breast milk, sweat, genito-urinary and gastro-intestinal tracts,
secretions of the lungs, etc. IgA plays an important role in protection against
respiratory, urinary tract and bowel infections and it is probably also important
in preventing absorption of potential antigens in the food we eat.
Its significant presence in colostrum and breast milk indicates that it can be
transferred across the gut mucosa in the neonate and plays an important role in
protecting the neonate from infection.
IgD (structure is monomeric)
IgD is primarily a cell membrane immunoglobulin found on the
surface of B lymphocytes and accounts for less than 1% of the
total immunoglobulin pool.
While their serum function is not fully understood, they are
known to initiate immune response on the B-cell surface (is
expressed on B cells as an antigen receptor).
IgD antibodies are found in small amounts in the tissues that
line the belly or chest.
IgE (structure is monomeric)
Athough difficult to find (constituting about .002% of immunoglobulins), IgE antibodies are
of major importance as mediators of allergic reactions and are also generally responsible
for an individual's immunity to invading parasites.
IgE antibodies are found in the lungs, skin, and mucous membranes. They cause the body
to react against foreign substances such as pollen, fungus spores, and animal dander by
triggering the mast cells to release histamine along with a variety of other mediators that
result in allergic symptoms such as increased vascular permeability, skin rashes,
respiratory tract constriction (wheezing), and increased secretions from epithelium (watery
eyes, runny nose).
This may occur in allergic reactions to milk, some medicines, and some poisons. Thus,
IgE antibody levels are often high in people with allergies.
IgE also plays a role in parasitic helminth diseases. Since serum IgE levels rise in parasitic
diseases, measuring IgE levels is helpful in diagnosing parasitic infections.
Figure 15.15
Figure 15.13