Immunology

Question 1

Types of Immunity

Answer 1

Innate / Non-specific
- Born with it
- First line of defense
- Physical barriers, NK cells, inflammation

Adaptive / Specific:
- Develops after birth during exposure to antigens
- Four main properties:
Specificity, Versatility, Memory and Tolerance
- Cytotoxic T + B cells and Antibodies

Question 2

Non-Specific Types of Defense (7)

Answer 2

1) Physical Barrier
2) Phagocytes: Engulf pathogens and cell debris
3) Immune surveillance:
Destruction of abnormal cells by NK cells
4) Interferons:
Chemical messengers that coordinate defenses against viral infections
5) Complement:
Circulating proteins that assist antibodies in destroying pathogens
6) Inflammation:
Localized, tissue level response that prevents the spread of injury or infection.
7) Fever:
Elevation of body temp. that accelerates defenses and tissue metabolism

Question 3

What is the difference between cell mediated and antibody mediated immunity?

Answer 3

Cell mediated immunity destroys cells via cytokines and lysis.

Antibody mediated immunity destroys pathogens by producing specific antibodies against antigens.

Question 4

Helper T cells: How do they help?

Answer 4

Release cytokines to stimulate the effects of specific and non-specific defenses. These cytokines will activate other cells in both the specific and non specific category.

Question 5

What are APC’s and what do they do?

Answer 5

Antigen Presenting Cells display antigens on their surface without being infected.
- Have Class II proteins
- Activate Helper T cells
- Macrophages in CT
- Microglia in CNS

Question 6

What are Class I + II MHC’s?

Answer 6

Major Histo-compatibility Complex
Class I:
- Cells displays infected antigen and results in cells destruction
- Only on nucleated cells
- Communicates with CD8 T cells

Class II:
- On specialized cells
- Communicates with CD4 T cells
- Results in stimulated immune response against specific antigen.

Question 7

CD4 v CD8 cells

Answer 7

CD4 cells:
- Class II MHC
- Helper functions

CD8 cells
- Class I MHC
- Cytotoxic functions

Question 8

What are the most effective ways to fight a bacterial infection?

Answer 8

• Phagocytosis
• Antigen presentation
• Activation of cytotoxic and T and B cells
• Antibody production
• Destruction of bacteria via lysis or phagocytosis

Question 9

What are the most effective ways to viral infection?

Answer 9

• Cells get infected
• Interferons are released - improving resistance
• Antigen presentation
• Activation of T cells, B cells and NK cells
• More antibodies are produced
• Destruction of viruses or prevention of virus cell entry

Question 10

Immunity: First and Second exposures

Answer 10

First exposure to a specific antigen = primary response.
This response time is slower as cells need to be activated

Second (and subsequent) exposure to the same antigen = Very rapid response because of lg numbers of memory B cells. This is considered immunity.

Question 11

Forms of Adaptive Immunity (4)

Answer 11

1) Non-specific Immunity

2) Specific Immunity

2a) Active Immunity:

I) Naturally Acquired (Getting sick)

II) Artificially Acquired (Vaccination)

2b) Passive Immunity:

III ) Naturally Acquired (Antibodies transferred during child birth)

IV) Artificially Acquired (Assistance from outside sources)

Question 12

Natural defenses against cancers

Answer 12

Cancer cells are mutated “self” cells but despite this, the body is usually able to recognize and destroy them via interferons, macrophages, NK cells and cytotoxic cells

Question 13

Immunity v Autoimmunity

Answer 13

Immune response are essential to fighting infections, but an overactive immune response could lead to autoimmunity which could include:
- unnecessary inflammation
- Attacking “self” cells