(7-18) Adaptive Immunity -ii-

Question 1

What is adaptive immunity?

Answer 1

Each time the body is exposed to foreign material, the immune system learns to recognize and later remembers the most effective response for invaders.

Question 2

What are the 2 basic strategies utilized in adaptive immunity?

Answer 2

1. Humoral Immunity
   ~ B-cells & antibodies
2. Cellular immunity
   ~ T-cells

Question 3

Is Antigen binding to B-cell surface antibody enough to cause clonal expansion?

Answer 3

No, it requires a second signal from a helper T cell (TH).

Question 4

Describe the 5-step “double check” system that ensures an antibody response is truly warranted.

Answer 4

1. Antigen binds the B-cell surface Antibody
2. Antigen is internalized into the B-cell, degraded, and “presented” on the surface of the B-cell.
3. The Ab is presented in the groove of an MHC Class II molecule to T-Cell Receptor (TCR) on TH cell.
4. If TH cell does not recognize the presented peptide (i.e., it’s “non-self”), cytokine signal is sent that activates B-cell.
5. Clonal expansion occurs

Question 5

What are T-Independent Antigens?

Answer 5

Antigens that cause clonal expansion of B-cells without TH-cells.

Question 6

Polysaccharides and lipopolysaccharides (LPS from Gram-negative bacteria) that have multiple repeating units, such as the capsule of Streptococcus pneumoniae, are what type of antigens?

Answer 6

T-Independent Antigens

Question 7

How do TH-Cells Help macrophages? List 5 steps.

Answer 7

1. Macrophage phagocytoses invading microbe
2. Microbe is degraded by lysosyme
3. Degraded microbe parts are presented in MHC II on cell surface
4. TH cell TCR does not recognize the presented peptide (“non-self”)
5. Cytokine signal activates macrophage

Question 8

Why are macrophages activated?

Answer 8

Activated macrophages are bigger and better at killing.

Question 9

Which 3 types of cells phagocytose microbes and and present them to T cells?

Answer 9

1. B-cells
2. Neutrophils
3. Dendritic cells

Question 10

What are the 2 T-Lymphocyte Populations?

Answer 10

1. Helper T cells (TH)

2. Cytotoxic T cells (TC)

Question 11

What 3 tasks/ attributes are affiliated with Cytotoxic T cells (TC)?

Answer 11

1. Proliferate and differentiate to destroy infected or cancerous cells
2. Have a CD8 marker
3. Recognize MHC I

Question 12

What 5 tasks/ attributes are affiliated with Helper T cells (TH)?

Answer 12

1. Activates B cells and macrophages
2. Stimulates other T cells
3. Orchestrates immune response
4. Its T-Cell Receptor (TCR) recognizes antigen display by MHC II
5. Has CD4 marker on cell surface

Question 13

What do MHC class II bind?

Answer 13

MHC class II bind exogenous antigen (peptide)

Question 14

How are exogenous antigens (peptides) defined?

Answer 14

Antigens that were extracellular before the macrophage phagocytosed them, or before the B-cell internalized them.

Question 15

Where is MHC class II found, and which T-lymphocyte is it associated with?

Answer 15

1. MHC class II is found on B-cells and phagocytic cells.

2. It is associated with TH.

Question 16

Where is MHC class I found, and which T-lymphocyte is it associated with?

Answer 16

1. MHC class I is found on all cells.

2. It is associated with TC.

Question 17

How do TC-Cells Destroy Cells?

Answer 17

If MHC I displays non-self peptide, TC sends a signal that destroys the cell.

Question 18

Under which 2 conditions does a TC cell destroy a cell?

Answer 18

1. cell is infected with virus/ intracellular microbe
2. If a cell has a “new” protein
   ~ ex. mutation that is causing cancer

Question 19

When will a TC cell not kill a cell?

Answer 19

If a cell displays self peptide on MHC I, a TC cell will ignore it