Sistem imun 5.

IMMUNE SYSTEMBy :

Cici Rizky Y 120210103016

Adha Qiftiyatul M 120210103020

Wulan Anggraeni 120210103048

Tesa Lusidyah 120210103052

What is the immune system?

The body’s defense against disease causing organisms, malfunctioning cells,

and foreign particles

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

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

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

Nonspecific response

Skin

Mucous membranes

Secretions

EXTERNAL INNATE IMMUNITY

- 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

- 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

- 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

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

ADAPTIVE IMMUNITY

- develops after exposure to agents such as microbes,

toxins, or other foreign substances

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)

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

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.

“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.

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.

B -Lymphocytes

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.

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.

B cells recognize

antigens,

Differentiate into plasma cells-produce more antibodies

Differentiate into memory cells-keep some for later

proliferate,

and produce specific antibodies.

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

Different Immunoglobulins

Type Number of

ag binding

sites

Site of action Functions

IgG 2 •Blood

•Tissue fluid

•CAN CROSS

PLACENTA

•Increase

macrophage activity

•Antitoxins

•Agglutination

IgM 10 •Blood

•Tissue fluid

Agglutination

IgA 2 or 4 •Secretions (saliva,

tears, small intestine,

vaginal, prostate,

nasal, breast milk)

•Stop bacteria

adhering to host

cells

•Prevents bacteria

forming colonies on

mucous membranes

IgE 2 Tissues •Activate mast cells

HISTAMINE

•Worm response

INTERACTION OF ANTIGENS - ANTIBODIES

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.

ANTIGEN

Antigen-

binding

sitesAntibody A

Antigen

Antibody BAntibody 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

Antibodies as Receptors

Antibodies can

attach to B cells,

and serve to

recognize foreign

antigens.

Antigens as Effectors

Free antibodies can

bind to antigens,

which “tags” the

antigen for the

immune system to

attack and destroy.

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

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

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

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

Depending on their source

Peptide antigens are handled by

different classes of MHC molecules

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

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

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

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 cellsClone 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

PRIMARY AND SECONDARY IMMUNE RESPONSE

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.

ALERGY AND ABNORMALITY OF

IMMUNE SYSTEM

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

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

Smallpox

Symptoms

Red spots containing transparent fluid all over body.

Spots fill with pus

Eyelids swell and become glued together

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

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.

THANK YOU FOR YOUR ATTENTION

WASSALAMUALAIKUM WR.WB