8 2 bio265 microbiology and immunology_2 instructor dr di bonaventura
Sistem imun 5.
1. IMMUNE SYSTEMBy :
Cici Rizky Y 120210103016
Adha Qiftiyatul M 120210103020
Wulan Anggraeni 120210103048
Tesa Lusidyah 120210103052
2. What is the immune system?
The body’s defense against disease causing organisms, malfunctioning cells,
and foreign particles
3. IMMUNE SYSTEM
Adaptive Immune System
(Specific respon)
Innate Immune system
(Non specific respon)
Disorders and
disease
External
Defense
Internal
Defense
-Skin
-Mucous
membranes
-secretorions
-Phagocytic cells
-Antimicrobial
subtance
-Inflammatory
response
-Natural killer cells
Limfosit T Limfosit B
4. Immune System : 2 branches
1. The Innate Immune system =
- is present before any exposure to pathogens and is effective
from the time of birth
2. The Adaptive Immune System =
- develops after exposure to agents such as microbes, toxins, or
other foreign substances
5. INNATE IMMUNITY
Innate immunity is present before any exposure to
pathogens and is effective from the time of birth
It involves nonspecific responses to pathogens
Innate immunity consists of external barriers plus internal
cellular and chemical defenses
7. - Phagocytic cells
There are different types of
phagocytic cells:
- Neutrophils engulf and destroy
microbes
- Macrophages are part of the
lymphatic system and are found
throughout the body
- Eosinophils discharge
destructive enzymes
- Dendritic cells stimulate
development of acquired
immunity
Pseudopodia
surround
microbes.
1
Microbes
are engulfed
into cell.
2
Vacuole
containing
microbes
forms.
3
Vacuole
and lysosome
fuse.
4
Toxic
compounds
and lysosomal
enzymes
destroy microbes.
5
Microbial
debris is
released by
exocytosis.
6
Microbes
MACROPHAGE
Vacuole Lysosome
containing
enzymes
INTERNAL INNATE IMMUNITY
8. - Antimicrobial substance
Peptides and proteins function in innate defense by
attacking microbes directly or impeding their
reproduction
Interferon proteins provide innate defense against viruses
and help activate macrophages
About 30 proteins make up the complement system,
which causes lysis of invading cells and helps trigger
inflammation
INTERNAL INNATE IMMUNITY
9. - Inflammatory response
• Inflammation can be either local or systemic (throughout the body)
• Fever is a systemic inflammatory response triggered by pyrogens released by
macrophages, and toxins from pathogens
• Septic shock is a life-threatening condition caused by an overwhelming inflammatory
response
INTERNAL INNATE IMMUNITY
10. Natural killer cells
All cells in the body (except red blood cells) have a class 1
MHC protein on their surface.
Cancerous or infected cells no longer express this protein;
natural killer (NK) cells attack these damaged cells
INTERNAL INNATE IMMUNITY
12. T-Lymphocytes
Mature T-cells have T cell receptors which have a very similar structure to
antibodies and are specific to 1 antigen.
They are activated when the receptor comes into contact with the Ag with
another host cell (e.g. on a macrophage membrane or an invaded body
cell)
13. T-Lymphocytes
After activation the cell divides to form:
T-helper cells – secrete CYTOKINES
help B cells divide
stimulate macrophages
Cytotoxic T cells (killer T cells)
Kill body cells displaying antigen
Memory T cells
remain in body
14.
15. Helper T cells
Helper T-cells have receptors for recognizing antigens.
If they are presented with an antigen, they release
cytokines to stimulate B-cell division.
The helper T-cell is the key cell to signal an immune
response. If helper T-cells are disabled, as they are in
people with AIDS, the immune system will not respond.
16. “Killer” T cells
While B-cells divide and differentiate, so do T-cells.
Some T-cells become cytotoxic, or “killer” T-cells. These T-
cells seek out and destroy any antigens in the system, and
destroy microbes “tagged” by antibodies.
Some cytotoxic T-cells can recognize and destroy cancer cells.
17. B cells
B-cells in general produce antibodies. Those with antibodies that
bind with the invader’s antigen are stimulated to reproduce rapidly.
B-cells differentiate into either plasma cells or memory B-cells.
Plasma cells rapidly produce antibodies. Memory cells retain the
“memory” of the invader and remain ready to divide rapidly if an
invasion occurs again.
19. B -Lymphocytes
Some activated B cells PLASMA CELLS these produce lots of antibodies, <
1000/sec
The antibodies travel to the blood, lymph, lining of gut and lungs.
The number of plasma cells goes down after a few weeks
Antibodies stay in the blood longer but eventually their numbers go down too.
20. B -Lymphocytes
Some activated B cells MEMORY CELLS.
Memory cells divide rapidly as soon as the antigen is reintroduced.
There are many more memory cells than there were clone cells.
When the pathogen/infection infects again it is destroyed before any
symptoms show.
21. B cells recognize
antigens,
Differentiate into plasma cells-
produce more antibodies
Differentiate into memory cells-
keep some for later
proliferate,
and produce
specific
antibodies.
22. Antibodies
Also known as immunoglobulins
Globular glycoproteins
The heavy and light chains are polypeptides
The chains are held together by disulphide bridges
Each ab has 2 identical ag binding sites – variable regions.
The order of amino acids in the variable region determines
the shape of the binding site
26. ANTIGEN
a substance or molecule that is recognized by the
immune system. The molecule can be from
foreign material such as bacteria or viruses.
Anything that can trigger this immune response is
called an antigen. An antigen can be a microbe
such as a virus, or even a part of a microbe.
Tissues or cells from another person (except an
identical twin) also carry nonself markers and act
as antigens.
28. Antigen-
binding
sitesAntibody A
Antigen
Antibody B
Antibody C
Epitopes
(antigenic
determinants)
An antigen is any foreign molecule
That is specifically recognized by lymphocytes
and elicits a response from them
A lymphocyte actually recognizes and binds
To just a small, accessible portion of the antigen
called an epitope
Picture Source : campbell
An antibody is a
substance formed
immunity in human
blood in response to
antigenic stimulus and
will react specifically
with antigen
29. Antibodies as Receptors
Antibodies can
attach to B cells,
and serve to
recognize foreign
antigens.
30. Antigens as Effectors
Free antibodies can
bind to antigens,
which “tags” the
antigen for the
immune system to
attack and destroy.
31. Antigen Recognition by Lymphocytes
The vertebrate body is populated by two main types of lymphocytes
B lymphocytes (B cells) and T lymphocytes (T cells)
Which circulate through the blood
The plasma membranes of both B cells
and T cells
Have about 100,000 antigen receptor that all recognize the same epitope
32. Antigen-
Binding site
b chain
Disulfide bridge
a chain
T cell
A T cell receptor consists of one
a chain and one b chain linked by
a disulfide bridge.
(b)
Variable
regions
Constant
regions
Transmembrane
region
Plasma
membrane
Cytoplasm of T cell
T Cell Receptors for Antigens and the Role of the MHC
Each T cell receptor
Consists of two different polypeptide chains
Figure 43.8b
V V
C C
Picture Source : campbell
33. T cells bind to small fragments of antigens
That are bound to normal cell-surface proteins called
MHC molecules
MHC molecules
Are encoded by a family of genes called the major
histocompatibility complex
34. Infected cells produce MHC molecules
Which bind to antigen fragments and then are
transported to the cell surface in a process called
antigen presentation
A nearby T cell
Can then detect the antigen fragment displayed on the
cell’s surface
35. Depending on their source
Peptide antigens are handled by
different classes of MHC molecules
36. Figure 43.9a
Infected cell
Antigen
fragment
Class I MHC
molecule
T cell
receptor
(a) Cytotoxic T cell
A fragment of
foreign protein
(antigen) inside the
cell associates with
an MHC molecule
and is transported
to the cell surface.
1
The combination of
MHC molecule and
antigen is recognized
by a T cell, alerting it
to the infection.
2
1
2
Class I MHC molecules, found on almost all
nucleated cells of the body
Display peptide antigens to cytotoxic T cells
Picture Source : campbell
37. Class II MHC molecules, located mainly on dendritic cells, macrophages, and
B cells
Display antigens to helper T cells
1
2
Figure 43.9b
Microbe Antigen-
presenting
cell
Antigen
fragment
Class II MHC
molecule
T cell
receptor
Helper T cell
A fragment of
foreign protein
(antigen) inside the
cell associates with
an MHC molecule
and is transported
to the cell surface.
1
The combination of
MHC molecule and
antigen is recognized
by a T cell, alerting it
to the infection.
2
(b)
Picture Source : campbell
38. Clonal Selection of Lymphocytes
In a primary immune response
Binding of antigen to a mature lymphocyte induces the
lymphocyte’s proliferation and differentiation, a
process called clonal selection
39. Clonal selection of B cells
Generates a clone of short-lived activated effector
cells and a clone of long-lived memory cells
Figure 43.12
Antigen molecules
Antigen
receptor
B cells that
differ in
antigen
specificity
Antibody
molecules
Clone of memory cells
Clone of plasma cells
Antigen molecules
bind to the antigen
receptors of only one
of the three B cells
shown.
The selected B cell
proliferates, forming
a clone of identical
cells bearing
receptors for the
selecting antigen.
Some proliferating
cells develop into
short-lived plasma
cells that secrete
antibodies specific
for the antigen.
Some proliferating cells
develop into long-lived
memory cells that can
respond rapidly upon
subsequent exposure
to the same antigen.
Picture Source : campbell
42. Primary Immune
Response
>> In the event the primary
response stimulation, cells
divide and hold precursor
differentiation into antibody-
forming cells that produce IgM
and IgG. During the process of
memory cells are formed,
which are still limited.
Secondary Immune
Response
>> In the event secondary response,
the cells sensitive to the antigen that
number is growing rapidly increased
antibody synthesis, is faster, more
durable, and more effective than the
previous response. That is because
the immune system has been more
ready to antigens as memory cells
prepared against antigens. These
memory cells that will eventually lead
to immunological memory.
45. Allergies
When the immune system responds to harmless substances
Allergens – antigenic substances which do no real harm
Allergens include house dust, animal skin, pollen, house dust mite and its faeces
46.
47. Allergies
Histamine causes blood vessels to widen and become leaky.
Fluid and white blood cells leave capillaries.
The area of leakage becomes hot, red and inflamed
48.
49. Smallpox
Symptoms
Red spots containing transparent fluid all over body.
Spots fill with pus
Eyelids swell and become glued together
50. Measles
Caused by an airborne virus
9th leading cause of death worldwide
Causes rash and fever
Can have fatal complications
Passive immunity from mothers in infants under 8 months
Now quite a rare disease in developed countries due to vaccination
51. Measles
Transmitted easily in overcrowded, insanitary conditions
Mainly affects malnourished infants with vitamin A deficiencies
Responsible for many cases of childhood blindness and can cause severe brain damage
Herd immunity of 93-95% needed to prevent transmission within a population.
