Lecture 12- 3rd line

Question 1

What cells are involved in the third line of defense (immune system)?

• What are they classified as?

Answer 1

Lymphocytes:

1. B-cells
2. T-cells

Question 2

What are the two benefits of the third line of defense?

Answer 2

1. Cause specific response for specific antigen
2. provides immunological memory for subsequent infections

Question 3

What are the 2 branches of adaptive immunity?

• What do they do/what cells are involved?

Answer 3

1) Humoral immunity

• Antibodies in body fluid and B-cells.
• Tags antigens for destruction

2) Cellular immunity

• T-cells attack infected cells
• causes lysis/helps antibody response

Question 4

Where are T-cells and B-cells matured for self-tolerance?

Answer 4

1. T-cells tested in thymus to see if they recognize MHC proteins
2. B-cells tested in bone marrow to see if they make antibodies to self-antigens

Question 5

What happens if lymphocytes don’t recognize self antigens?

Answer 5

Go to lymphoid tissue and undergo apoptosis (cell death)

Question 6

What is the part of an antigen that antibodies recognize and bind to?

Answer 6

Epitope

Question 7

What are these terms:

• How strong a reaction an antigen causes?
• When immune cells respond to something that isn’t a threat

Answer 7

• Immunogenicity
• Allergies

Question 8

When immune cells respond to own cells:

Answer 8

Autoimmunity

Question 9

What types of cells are antigen presenting cells?

Answer 9

1. Dendritic cells (innate)
2. Macrophages (innate)
3. B-cells (adaptive)

Question 10

How does antigen presentation work?

Answer 10

1. APC encounters microbe ingest microbe
2. APC goes to lymphoid organs
3. APC puts antigen parts on outside MHC 2
4. Presents antigens to T-cells

Question 11

How are T-cells and B-cells so specific?

Answer 11

Both cell receptos only recognize certain epitope

Question 12

What are the two types of T-cells?

• What do they do?

Answer 12

1. Cytotoxic T-cells
   
   1. Directly destroy infected/cancerous cells
2. Helper T-cells
   
   1. Secrete cytokines and stimulate other immune cells

Question 13

Why are cytotoxic t-cells able to identify infected cells?

Answer 13

Have CD8 protein attached

Question 14

How do Helper T-cells identify antigens?

Answer 14

Have CD4 proteins

Question 15

How does HIV effect T-cells?

Answer 15

Eliminate helper T-cells

• Can’t coordinate attacks

Question 16

Once helper T-cells are activated, what do they differentiate into?

• What do these subtypes do?

Answer 16

1. TH1
   
   1. ​destroy pathogens inside host cell
2. TH2
   
   1. Stimulate B-cells to make antibodies
3. Treg
   
   1. Helps response taper off

Question 17

What are the 4 stages of T-cell cellular response?

Answer 17

1. Antigen presentation
2. T-cell activation
3. T-cell proliferation/differentiation
4. Antigen eliminated and memory

Question 18

What molecules do cells contain for antigen presentation?

• What types of cells are they found on?

Answer 18

1. MHC 1
   * ​all cells
2. MHC 2
   * Antigen presenting cells

Question 19

Cells that present antigens with MHC 1 are typically:

What type of cells do they present antigens to:

Answer 19

Infected by the pathogen

• Presents antigen to cytotoxic T-cell

Question 20

How do MHC 1 cells present pathogens (steps)?

Answer 20

1. Cell breaks up pathogen in proteasome
2. Antigen sent to endoplasmic reticulum
3. MHC 1 protein binds antigen and move to cell surface

Question 21

Cells that present antigen by MHC 2 typically:

• What cells do they present them to?

Answer 21

Ingests pathogen

• Present to Helper T-cells

Question 22

MHC 2 cells present the pathogen in this way (steps of process):

Answer 22

1. Phagocytose cell
2. Pathogen encased in vesicle and bind with lysosome
3. Pathogen broken into antigens
4. MHC 2 binds antigen and go to cell surface