Lecture 18 and 19 Unit 3

Question 1

what are immune responses

Answer 1

altered cellular reactions following contact with a component of a specific foreign organism/product or antigen

Question 2

how is adaptive immunity distinguished from innate immunity

Answer 2

1. specificity for particular foreign molecules and tolerance for self proteins
2. memory of perviously encountered foreign antigens so that the second exposure prompts a more rapid and vigorous response

Question 3

what are the two types of adaptive immunity

Answer 3

1. cell-mediated immunity

2. antibody mediated immunity

Question 4

what does cell mediated immunity depend on

Answer 4

T cell receptors (TCRs) that are expressed on the surface of T cells

Question 5

what does cell mediated immunity do after recognizing foreign antigen presented by MHC I proteins?

Answer 5

defends the body against specific pathogens that live/exist inside of our cells by recognizing only foreign antigen presented by MHC I proteins

Question 6

what does cell mediated immunity do by not recognizing self-antigen presented by MHC I proteins?

Answer 6

is becomes tolerant of our own proteins

Question 7

what does antibody mediated immunity depend on

Answer 7

T cell receptors that are expressed on the surface of T cells in addition to other proteins used by B cells

Question 8

by recognizing foreign antigen that is processed then presented by MHC II proteins what does antibody mediated immunity do?

Answer 8

defends the body against specific pathogens that live/ exist outside of our cells

Question 9

by not recognizing self-antigen presented by MHC II proteins, what does antibody mediated immunity do?

Answer 9

become tolerant of our own proteins, nucleic acids, lipids, and polysaccharides

Question 10

what are the two properties of antigens

Answer 10

1. immunogenicity

2. reactivity

Question 11

what is immunogenicity

Answer 11

antigens stimulate proliferation of specific lymphocytes and antibodies

Question 12

what is reactivity

Answer 12

antigens react with activated lymphocytes and antibodies developed/released in response to them

Question 13

what do complete antigens exhibit

Answer 13

both properties and include foreign proteins, nucleic acids, some lipids, and large polysaccharides

Question 14

what are immune responses generated against

Answer 14

parts of antigens called epitopes

Question 15

after leaving the thymus what does tight binding mean?

Answer 15

recognition of a foreign antigen

Question 16

what are the 5 steps in which cell mediated immune response occurs

Answer 16

1. antigen presentation
2. antigen recognition
3. activation
4. proliferation and differentiation
5. action (destrcution of infected cell)

Question 17

what are the major roles in antigen presentation?

Answer 17

• to engulf antigens

- to present fragments of the antigen on their surface so that it will be recognized by T cells

Question 18

what are major Antigen presented Cells (APCs)?

Answer 18

dendritic cells, macrophages, and activated B cells

Question 19

what are the major initiators of adaptive immunity

Answer 19

dendritic cells

Question 20

what do dendritic cells do

Answer 20

migrate to lymph nodes and secondary lymphoid organs where they present antigens to T cells

Question 21

what are the major “parts” in antigen recognition

Answer 21

cluster designation markers (CD4 and CD8)

Question 22

what do helper T cells do in antigen recognition

Answer 22

express CD4 and they bind only to MHC II molecules

Question 23

What happens in activation

Answer 23

depending upon receptor type, costimulators can cause T cells to complete their activation or abort activation after binding to an antigen

Question 24

what happens to T cells without costimulation

Answer 24

• become tolerant to that antigen
• are unable to divide
• do not secrete cytokines

Question 25

what happens to T cells with costimulation

Answer 25

- enlarge proliferate and form clones | - differentiate and perform function according to their specific T cell class

Question 26

what do cytokines do in activation

Answer 26

costimulate T cells and T cell proliferation

Question 27

what is interleukin 1

Answer 27

a cytokine released by macrophages, and it costimulates helper T cells

Question 28

what does interleukin 1 do?

Answer 28

1. release interleukin 2 | 2. synthesize more IL 2 receptors

Question 29

what does IL 2 do?

Answer 29

- a key growth factor which sets up a positive feedback cycle that encourages activated T cells to divide - used to enhance the body defense against cancer

Question 30

what do perforin and lymphotoxin do?

Answer 30

cell toxins

Question 31

what do gamma interferons do

Answer 31

enhances the killing power of macrophages

Question 32

what do helper T cells do in proliferation and differentiation

Answer 32

regulatory cells that play a central role in the immune response

Question 33

what do T cells do after they recognize presented antigen and become activated?

Answer 33

- stimulate proliferation of other T cells )critical for cell and antibody mediated immunity - stimulate the B cell to proliferate and differentiate (critical for antibody mediated immunity)

Question 34

what would happen if there were no Helper T cells

Answer 34

there would be no adaptive immune response

Question 35

what is immunological memory

Answer 35

the increased number of helper T cells which express the unique TCR that can recognize the specific foreign antigen provides a defense against future infection

Question 36

what happens upon a second exposure to the same specific antigen

Answer 36

1. delay in recognition will be greatly reduced 2. the magnitude of the response ( number of effector cells) will be greatly increased * result is that the specific pathogen is defeated before any symptoms emerge and memory cells are generated

Question 37

what so cytotoxic T cells express and bind to?

Answer 37

express CD8 and bind to MHC I molecules

Question 38

what are the only cells that have the ability to directly attack and kill the other cells of our body

Answer 38

cytotoxic T cells

Question 39

what do cytotoxic T cells do

Answer 39

circulate throughout the body in search of body cells that display the antigen to which they have been sensitized (immune surveillance)

Question 40

what are the target of cytotoxic T cells?

Answer 40

- virus infected cells - cells with intracellular bacteria or parasites - cancer cells - foreign cells