Topic 11.1 – Defense Infectious Against Disease Higher Level Ms. S. Scott Human Health and Physiology J205.

Topic 11.1 – Defense Infectious Against Disease

Higher Level

Ms. S. ScottHuman Health and Physiology

J205

11.1

Assessment Statements11.1.1  Describe the process of blood clotting11.1.2  Outline the principle of challenge and response, clonal selection and memory cells as the basis of immunity11.1.3  Define active and passive immunity11.1.4  Explain antibody production11.1.5  Describe the production of monoclonal antibodies and their use in diagnosis and treatment11.1.6  Explain the principle of vaccination11.1.7  Discuss the benefits and dangers of vaccination

Clotting is triggered very rapidly following tissue injury and limit spread of invading pathogens into the blood stream.

11.1.1

The body has an internal mechanism to slow bleeding and begin healing.Bleeding stops because blood has the ability to form a clot.    . Blood clotting is made possible by plasma proteins and platelets.

11.1.1

Overall Reaction of Blood Clotting

Activator

Clotting Factors

Fibrin + RBC = Clot

11.1.1

When we cut ourselves, we cut small blood vessels.

When this happens, our body forms a clot.

A clot stops us from losing blood and from a foreign pathogen from entering into our body.

Process 1: Blood Clotting

11.1.1

A wound triggers a cascade of events by which a blood clot is formed.

First platelets collect at the site of the wound.

Platelets are small disc shaped cell fragments

Platelets do not contain a nucleus

Process 1: Blood Clotting

11.1.1

Process 2: Blood Clotting

Platelets build up at wound and seal off small breaks in blood vessels

11.1.1

Process 3: Blood Clotting

11.1.1

Process 4: Blood Clotting

Fibrin proteins form a mesh of fibres which traps red blood cells. These dry and become a scab which closes the wound.

11.1.1

Fibrin + RBC = Clot

11.1.2

Challenge and ResponseWhen the body is challenged by a foreign pathogen it will respond with both a non-specific and specific immune reaction

11.1.2

Lymphocytes Recognize Self

• Cells are identified by specific molecules lodged in the outer surface of the cell (plasma) membrane.

• These molecules are called glycoproteins ( a molecule that contains a carbohydrate and a protein)

11.1.2

Clonal SelectionThe majority of B cell clones will differentiate into antibody-producing plasma cells, a minority will become memory B cells (BM cells)

Each B lymphocyte has a specific antibody on its surface that is capable of recognizing a specific antigen

11.1.2

Polyclonal Selection

11.1.2

Infection and Immune Response

11.1.3

Types of Immunity

Passive immunity is due to the acquisition of antibodies from the mother via the placenta and milk. Also antibodies can be received by injections.

11.1.3

Types of Immunity

Active immunity is due to the production of antibodies by the organism, after the body’s defense have been exposed to antigens.

11.1.3

Types of Immunity

• Active Immunity – -- develops when a person is exposed to microorganisms or foreign substances and the person’s immune system responds.

• Passive Immunity –

- is acquired when antibodies are transferred from one person to another. - The recipients do not make the antibodies themselves

11.1.3

Types of Immunity

11.1.3

Types of Immunity Definitions of Immunity

Active Production of antibodies by organism itself after the body defense mechanism have been stimulated by an antigen

Passive Acquisition of antibodies from another organism in which active immunity has been stimulated

Artificial The antibodies are produced elsewhere and injected

Natural Your body produces its own antibodies

Review Active & Passive Immunity

• Is this active or passive immunity?– Antigen enters body….the body produces

antibodies to neutralize antigen.– NATURALLY ACQUIRED --- ACTIVE IMMUNITY

Review Active & Passive Immunity

• Is this active or passive immunity?– Antibodies passes from mother to fetus during

pregnancy – NATURALLY ACQUIRED --- PASSIVE IMMUNITY

Review Active & Passive Immunity

• Is this active or passive immunity?– Weakened or dead fragments of a microbe are

injected into the body….the body produces antibodies to neutralize microbe

– Artificially ACQUIRED --- Active IMMUNITY

Review Active & Passive Immunity

• Is this active or passive immunity?– Antibodies in a serum (i.e. antivenom used to

treat snake bites) are introduced to the body……– Artificially ACQUIRED --- PASSIVE IMMUNITY

11.1.4

Antibody Production: The Primary Response Step 1: Antigen Presentation

Macrophages take in antigen by endocytosis

Antigen

Macrophage

The macrophage processes the antigen and attaches it to a membrane protein called a MHC protein

The MHC protein is moved to the cell surface membrane by exocytosis so that the antigen is displayed on its surface.

MHC protein

11.1.4

Antibody Production: The Primary Response Step 2: Activation of Helper T-cell

Helper T-cells have receptors on their cell surface membranes which can bind to antigens presented by macrophages.

receptor

Helper T-cellHelper T-cell binds to macrophage presenting the

antigen

Macrophage sends a signal to activate the helper T-cell

11.1.4

Antibody Production: The Primary Response

B-cells have antibodies in their cell surface membranes

Inactive B-cell

Antibody

Antigens bind to the antibodies in the surface membranes of B-cells

Antigen

Step 3: Activation of B-lymphocytes

11.1.4

Antibody Production: The Primary Response An activated helper T-cell with

receptors for the same antigen binds to the B-cell

SIGNAL

The helper T-cell sends a signal to the B-cell, activating the B-cell.

11.1.4

Antibody Production: The Primary Response

The activated B-cell starts to divide by mitosis to form a clone of plasma cells.

Plasma cells are activated B-cells with a very extensive network of rough endoplasmic reticulum.

Plasma cells synthesis large amounts of antibody, which they excrete by exocytosis.

11.1.4

Antibody Production: Summary

B-cell ActivateHelper T-cell

Activate

Clone

MemoryCell Plasma Cell

Antibodies

Antibody Production: Summary

Macrophage

AntigenAntigen

11.1.5

Monoclonal Antibody Production• Antibody produced by a single

clone (type) of B lymphocytes• It consists of a population of

identical antibody molecules.

A monoclonal antibody has many uses in medicine because:They are stable moleculesThey can be used over a long period of time

11.1.5

Monoclonal Antibody Production

1. Antigens that correspond to desired antibody are injected into an animal (usually a mouse)

2. B-cells are produce by the above animal and the antibodies produced by B-cells are removed.

They are made from genetic engineering using mouse cells.

11.1.5

Monoclonal Antibody Production3. Tumour cells are obtained. These cells

grow and divide endlessy.4. B-Cells from above animals are fused with

tumour cells, producing a cell called a hybridoma.

5. These hybridoma divide endlessly and produce a lot of the desire antibodies.

6. The hybridoma cells are culture & the antibodies they produce are purified and extracted

11.1.5

Monoclonal Antibody Production

11.1.5

11.1.5

Determine/ diagnose pregnancy– Pregnant women

produce a urine with high concentration of human chorionic gonadotrophin (HCG)

– Monoclonial antibodies that bond with HCG have been engineered to also carry color granules.

– Thus a change in color in a pregnancy test confirms pregnancy.

Uses of Monoclonal Antibodies

11.1.5

Treatment of Disease– Cancer cells carry

specific tumour-associated antigens (TAA) on the cell (plasma) membrane

– Monoclonial antibodies to TAA have been produced….

– These antibodies as carry drugs to kill the cancer cell

Uses of Monoclonal Antibodies

11.1.6

Principles of Vaccination

A weakened pathogen is injected into the body to generate an immune response and produce memory B cells.Vaccines don’t prevent infections, but on subsequent exposure to the pathogen the secondary immune response is faster.

11.1.6

Vaccination and the Immune System

A .

C .

B .

D .

L ev e l o fan tib o d y

L ev e l o fan tib o d y

L ev e l o fan tib o d y

L ev e l o fan tib o d y

V I

V I

V I

V I

Tim e

T im e

T im e

T im e

V = Vacc in a tio n I = In fec tio n

V= Vaccination I=Infection • Sometimes two or more vaccinations are needed to stimulate the production of enough antibodies to fight off a disease.

11.1.6

Vaccination and the Immune System

A .

C .

B .

D .

L ev e l o fan tib o d y

L ev e l o fan tib o d y

L ev e l o fan tib o d y

L ev e l o fan tib o d y

V I

V I

V I

V I

Tim e

T im e

T im e

T im e

V = Vacc in a tio n I = In fec tio n

V= Vaccination I=Infection • The first vaccination causes little antibody production and the production of some memory cells.

11.1.6

Vaccination and the Immune System

A .

C .

B .

D .

L ev e l o fan tib o d y

L ev e l o fan tib o d y

L ev e l o fan tib o d y

L ev e l o fan tib o d y

V I

V I

V I

V I

Tim e

T im e

T im e

T im e

V = Vacc in a tio n I = In fec tio n

V= Vaccination I=Infection • The second vaccination, called a booster shot causes a response from the memory cells & therefore a faster & greater production of antibodies.

11.1.7

Benefits and Dangers of VaccinationBenefits Dangers

Elimination of disease Neurotoxic side effects due to mercury-based preservatives

Decreased spread of epidemics Overload of immune system

Cost-effective preventative medicine Anecdotal evidence of autism associated with MMR

Decrease in symptoms associated with disease

Allergic reactions and autoimmune responses