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Immunology
• We have specific and a non-specific response sytems
• Non-Specific = barriers, like skin and mucus, HCl in the stomach, and phagocytosis.
• Specific = Immune system and antibodies
Phagocytosis – using Lytic Enzymes (hydrolysis)
Absorption
Role of Histamine
• Histamine is a hormone which is released at a damaged site
• Inflammation causes dilation of blood vessels
• More phagocytes are delivered to the damaged area.
The Specific Response
• Slower than the Non-Specific• Longer lasting• Responds to ANTIGENS
- Proteins/Glycoproteins (see cell membrane notes) on the cell surface membrane which trigger an immune response.
• Utilises white blood cells-LYMPHOCYTES (B and T Lymphocytes)
B Lymphocytes – from stem cells in bone marrow
T Lymphocytes
Made in the Thymus Gland.
Two types of Specific Immunity
• Cell-Mediated Response (uses T Lymphocytes)
• Humoral Response (uses B Lymphocytes)
Cell Mediated Response.
• This is a response that occurs when our cells have been infected – e.g. by a virus
• Infected cells (and macrophages) display the foreign antigens on their cell surface membrane
• One of our many T-helper cells will be complementary to these antigens
The T-helper cells stimulate the cloning of cytotoxic T cells
Complementary shapes Antigen of pathogen
Chemicals are released which cause MITOSIS of the correct cytotoxic T cells
Mitosis of T cells
Stimulated by the T-helper cells
Cloning of Killer T cells
How T cells protect us
• They kill infected cells by producing a protein which destroys the cell membrane
• They stimulate Phagocytes
• They stimulate B cells to divide
• They form T memory cells
Cell-Mediated Immunity
YouTube - Cell Mediated Immune Response
The Humoral Response
• This process involves B Lymphocytes and the production of antibodies
• It begins in the same way as the cell-mediated response.
Complementary shapes
Antigen of pathogen
Chemicals are released which cause MITOSIS of the correct cytotoxic T cells
AND B CELLS
B Cell cloning occurs by mitosis
B Cell
Antigen of pathogen
Cytokines released by T helper cells
This cell could be a B cell or a macrophage
B Cells
• Cloned B Cells can form PLASMA CELLS or MEMORY CELLS
• Plasma Cells – produce Antibodies
Antigen presenting by B cell or macrophage
Cloning/Mitosis
Complementary B cell
Produces antibodies
Complementary T-helper cells will release chemicals to stimulate mitosis
B Memory Cells• Stay in our tissues for many years.
• They carry out mitosis immediately upon contact with the complementary antigen
• A very quick, secondary response
• We do not become ill
• The same process with T memory cells
So, how do vaccines work?
Humoral Response
• YouTube - Antibody Mediated Immune Response
Summary of both types of Immunity
• YouTube - Review of Antibody and Cell-mediated Immunity
Antibodies
Definition of antibody
• An immunoglobulin protein that is produced by B plasma cells in response to non-self antigens.
The Antigen-Antibody Complex
• The antibodies attach to the antigen on the pathogen and destroy it.
MUST be a Complementary variable
region!
Funny animation link
• YouTube - Immune System Animation
Why do we get flu more than once?
• Antigenic Variability!
• Some antigens constantly change (mutation)
• Memory cells are no longer complementary
• The Primary Response is initiated instead of the secondary response.
Pathogens have many antigens
• So we produce many different types of antibody – POLYCLONAL antibodies
• Scientists can clone antibodies in the laboratory
• They can clone just one kind at a time
• These are MONOCLONAL antibodies
Monoclonal Antibodies
• These antibodies are complementary to a specific protein.
• Can be used to mark and identify proteins in blood or urine
• E.g. in Pregnancy tests, or drug tests in athletes
Uses in cancer treatment
• Cancer cells will present antigens on their surface membrane
• Specific monoclonal antibodies will attach to these cells and can activate a cytotoxic drug to kill the cell.
Uses in Transplant Surgery
• Transplanted organs often suffer rejection from the action of our T Cells
• Monoclonal antibodies can attach to and “knock out” these T Cells.
Other use
• The monoclonal antibody can be used to label and separate a chemical in a mixture.
• Read pages 110-111 and discuss the ethical issues associated with monoclonal antibodies, and how society uses scientific knowledge to inform decision-making.
Vaccines• You should now understand how
vaccines work.
But what makes a successful vaccine?
A Successful Vaccination Programme
• Must be economically viable to produce enough for a vulnerable population
• Have few side-effects
• Easy to store and transport
• Trained staff must be available
• It must be possible to carry out HERD IMMUNITY i.e. to immunise a total population
Evaluating vaccines
• They may not eliminate a disease because...
- Individuals may have a poor immune system
- Disease may spread BEFORE the vaccine has produced the required memory cells
- The pathogen could mutate
- There may be too many antigens on the pathogen (e.g. cold virus / HIV)
- People may object –e.g Religion, MMR
Cholera and TB Vaccine Evaluation• Cholera has high antigenic variability
• Populations are now more mobile so diseases spread much more easily
• HIV cases have risen so more people get TB
• Poverty and wars create overcrowded conditions so TB cases have risen
• More elderly people so more TB.
Now complete the Application questions!