Topic 21 - Immune System 2

Question 1

Learning Objectives

Answer 1

1. Define the different types of adaptive immunity
2. Describe the main cell types involves in mediating adaptive immune responses
3. Recognise that there must be a way for the powerful adaptive immune system to “tolerate self”
4. Identify the 2 types of immunological tolerance:
   - Central
   - Peripheral
5. Understand that a break down in immunological tolerance may lead to the developing of autoimmune disease
6. Recognise that human disease is a conspiracy between our genes and the environment in which we live
7. Link immunity to the cause and cure of some common human diseases
8. Discuss using examples that targeting the immune system is leading to breakthroughs in the fight against human disease including
9. Autoimmune diseases:
   - Organ specific or systemic
   - Cancer

Question 2

Dendritic cells

Answer 2

• Present antigens to lymphocytes
• Skin, gut and lungs (peripheral tissue)
• Use their dendrites to survey area and find danger
• Take up pathogens and break into antigens

Question 3

Adaptive immune system cells in splesecondary lymphoid organs

Answer 3

• Dendrite cells move from peripheral cells to secondary lymphoid organs, carrying antigens with them
• Dendritic cells then activate lymphocytes

Question 4

Adaptive immune system

Answer 4

Lymphocytes:
- Lymphocytes express receptors that specifically recognise a wider variety of antigens
- Requires expansion and differentiation od the innate immune system to eliminate microbes
- 2 Types of lymphocytes (B & T cells)

Question 5

Thymus

Answer 5

• Generative/ primary lymphoid organ
• Matures T-cells to make them target pathogens and not self

Question 6

Types of Adaptive Immunity

Answer 6

Hormonal Immunity:
- B-Cells secrete antibodies that eliminate extracellular microbes

Cell-mediated Immunity:
- T-Cells help phagocytes to destroy ingested microbes and kill infected cells

Question 7

Antibodies

Answer 7

• As part of hormonal immunity, antibodies are produced by B-cells.
• Antibodies are proteins

[heft]

Question 8

Antibody anatomy and function

Answer 8

Variable regions:
- Area binding to antigens using antigen-binding site
- Uses extention to help eliminate pathogens

Constant region:
- Determines the type of antibody

Question 9

Types of T-cells

Answer 9

Helper:
- Help B-cells produce antibodies
- Help macrophages and phagocytes digest microbes
- Some suppress and regulate immune response

Cytotoxic:
- Kill infected cells
- Detect and eliminate tumour cells

Question 10

Immunological tolerance

Answer 10

Central tolerance:
- Occurs in primary lymphoid organs

Peripheral tolerance:
- Mediated primarily by regulatory T-cells
- Occurs in peripheral tissues and secondary lymphoid organs

• A breakdown in immunological tolerance leads to autoimmune disease.

Question 11

Autoimmune disease

Answer 11

• Caused by genetic OR environmnental factors
• Many autoimmune diseases are linked to the genes responsible for T-cell activation and maintaining immunological response.

Question 12

Environmental factors of autoimmune disease

Answer 12

• often preceeded by an infection
• Other host and env. factors may contribute (local trauma leading to inflammation)

Question 13

Multiple sclerosis [heft]

Answer 13

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Question 14

Immune surveillance

Answer 14

• Immune system detecting and destroying tumout cells
• First recognised due to patients with tumours full of T and B cells

Question 15

New cancer therapies that target the immune system

Answer 15

Bone Marrow transplantation:
- Certain types of leukemia

Re-engeneered T-cells:
- Chimeric antigen receptor T-cells

Antibodies:
- Remove immunological brakes
- Apply immunological accelerator