Introduction to Immunology

Question 1

What is the need for an immune system? - -

Answer 1

Protection against infectious organisms - bacteria, viruses, fungi, protozoans, worms Protection against cancer

Question 2

Name the two major systems of immunity:

Answer 2

Innate Immunity Adaptive Immunity

Question 3

What is innate immunity? - Facts about innate immunity: - - - - What is it comprised of? - - -

Answer 3

'’A first line of defence’’ - Present at birth - Responds rapidly - Has no specificity - Has no memory Comprised of: - Barriers - Cells - Soluble factors

Question 4

Name the physical barriers of innate immunity - -

Answer 4

• Impermeable outer surface, e.g. skin, epithelial cell layer lining mucosal surfaces - Cilia in nasal passages and bronchi

Question 5

Explain how cilia work 1. 2.

Answer 5

1. Airborne bacteria are trapped on mucus secreting goblet cells 2. Cilia waft bacteria back towards mouth and nose

Question 6

Name the chemical barriers of innate immunity - - -

Answer 6

• Acidity in stomach - Alkaline secretions - Lysozyme in tears: enzyme which can attack cell walls

Question 7

What is the biological barrier of innate immunity?

Answer 7

Competition between commensal organisms with pathogenic micro-organisms that may try to invade

Question 8

Cells involved in innate immunity and their function: - - -

Answer 8

• Phagocytes: eat up foreign material - Natural Killer (NK) cells: kill tumour cells and virally infected cells - Eosinophils: attack and kill parasites

Question 9

Explain the action of phagocytes: - - - -

Answer 9

• Adhere to bacterium - Engulfs into membrane bound vesicle - Meets with lysozyme which empties its contents - Lysozyme will attack and breakdown bacterium

Question 10

Soluble factors of innate immune system: - - - -

Answer 10

• Lysozyme - Complement - Cytokines, particularly interferons - Acute phase proteins

Question 11

What is the key thing between different aspects of the innate immune system?

Answer 11

Cooperation between components of the innate immune system, they also cooperate with the adaptive immune system

Question 12

Adaptive immune system key features: - - - - - -

Answer 12

• Slow to start - Adaptive - Highly specific - Has memory (would eliminate micro-organism quickly second time round) - Recognition of self and non self - Has humoral and cellular components which cooperate together

Question 13

What does humoral immunity refer to? What are they?

Answer 13

Antibodies (immunoglobulins) are specific proteins produced against pathogens, produced by B lymphocytes

Question 14

What is cellular immunity?

Answer 14

Mediated by lymphocytes which recognise specific pathogenic structures called antigens

Question 15

Name the cells involved in cellular immunity: - -

Answer 15

• B lymphocytes - T lymphocytes

Question 16

What are the two principle types of T lymphocytes and their function?

Answer 16

• Helper T cells: help B cells produce antibodies - Cytotoxic cells: destroy own cells which have been infected by the virus

Question 17

Which response does this graph show?

How many days does it take for the antibody to respond?

What does this lead to?

Answer 17

• Primary (1⁰) Response
• There is more infectious agent being produced than antibodies
• It takes around 10 days to respond, which could lead to disease

Question 18

Draw the Secondary response graph:

Answer 18

Dark blue line = amount of infective agent

Light blue = antibody produced

Question 19

What is a vaccination thought to be?

Who were the pioneers?

Answer 19

The most successful application of immunological principles.

The pioneers in developing this were Edward Jenner and Louis Pasteur

Question 20

What are the two roles of the immune system?

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Answer 20

Recognition Function: identifies a substance or body (antigen) as foreign

Effector Function: removes foreign invader

Question 21

What is an antigen?

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What are antigenic determinants recognised by?

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Answer 21

• Any substance which elicits an immune response
• Portion recognised is called the epitope or antigenic determinant

Antiigenic determinants are recognised by:

• Antibodies (humoral)
• T cells (cellular)

but the two see different epitopes

Question 22

Types of Antigens

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What is the key point?

Answer 22

• Proteins
• Carbohydrates
• Nucleic acids
• Lipids
• Drugs e.g. penicillin
• Inorganic molecules of nickel

Key point is: Antigens are foreign (non-self)