7.5 Immune

Question 1

What causes the immune response to fever? Function?

Answer 1

Pyrogens – secreted by macrophages
Cause hypothalamus to elevate the body’s set temperature (fever)
Moderate fever can be beneficial, as it causes:
The liver and spleen to sequester iron and zinc (needed by microorganisms to grow and divide)
Increase rate of chemical reactions which speeds up tissue repair

Question 2

How does early inflammation work?

Answer 2

Inflammatory Chemical Release
Vasodilation and Increased Vascular Permeability
Phagocyte Mobilization

Question 3

What are cytokines? What are associated with inflammation?

Answer 3

Immune signaller
Interleukins
Tumor necrosis factor

Question 4

What are acute phase proteins?

Answer 4

Inflammatory proteins released by the liver
C-reactive Protein: ** lab test for inflammation
fibrinogen ** causes increased red blood cell sedimentation – lab test for inflammation

Question 5

What is the difference between acute and chronic inflammation?

Answer 5

Acute Inflammation: rapid response to cell injury
removes agent of injury
enhances healing
terminates quickly
Chronic Inflammation: persistent inflammation
inhibits healing
continued cellular damage and/or organ dysfunction

Question 6

In general, what are the characteristics of the adaptive immune system?

Answer 6

antigen-specific - requires the production of specific lymphocytes and antibodies against a specific antigen
systemic - not restricted to the initial infection site
has memory -second encounter causes a more rapid and vigorous response

Question 7

What are B-cells? Which kind of immunity?

Answer 7

Born AND mature in the Bone Marrow
Housed in lymphoid tissues
Recognize free pathogens (bacteria, toxins, viruses)
Involved in Antibody-mediated Immunity

Question 8

What are T-cells? Which kind of immunity?

Answer 8

Born in Bone Marrow, mature in Thymus
Housed in lymphoid tissues
Recognize infected or cancerous body cells
Involved in Cell-Mediated Immunity
Involved in activating total, combined immune responses

Question 9

What is an antigen?

Answer 9

are any molecule or partial molecule that can trigger an immune response

Question 10

How do B/T-cells become immune competent?

Answer 10

To display receptor- have to become immunocompetent= display a unique receptor for a single pathogen
THEN, go to lymphoid tissue where may encounter antigen, only become mature/activated AFTER binding to antigen

Question 11

Where do lymphocytes originate and mature?

Answer 11

origin: bone marrow, hematopoietic stem cells
maturation: bone marrow (B-cells) or thymus (T-cells)

Question 12

Why do lymphocytes need to be able to ID “self”?

Answer 12

able to recognize “self” cells and be unresponsive to self-antigens
positive selection: maintain only cells that recognize “self” proteins - MHC
negative selection: remove cells that are reactive to “self” - self-antigen

Question 13

How do lymphocytes activate? What happens next?

Answer 13

activation: happens when they actually encounter their specific antigen in the body
proliferation & differentiation: once activated, they will increase in number and make other immune cells (ex: memory cells)

Question 14

How are B-cells activated?

Answer 14

Specific B-Cell with BCR recognizes specific pathogen and makes:
Plasma Cells: produce specific antibodies for that pathogen
2000 antibodies per second
Lifespan 5-7 days
Memory Cells: store memory of antigens to produce antibodies upon later infection, lay dormant until 2nd infection by same pathogen

Question 15

How do B-cells proliferate and differentiate?

Answer 15

Plasma Cells: produce specific antibodies for that pathogen
2000 antibodies per second
Lifespan 5-7 days
Memory Cells: store memory of antigens to produce antibodies upon later infection, lay dormant until 2nd infection by same pathogen

Question 16

What are the 5 types of antibodies?

Answer 16

IgM- B-Cell receptor
IgG- Most common, high after a second exposure
IgA- mostly in mucous membrane
IgE- parasitic/allergic; hypersensitivity
IgD- hypersensitivity

Question 17

How does an antibody-mediated response get rid of a pathogen?

Answer 17

Neutralization: combine with molecules, viruses to physically prevent them from interacting with cells
Agglutination: clump molecules, bacterial cells together, render non-functional
Precipitation: separate them from solution like a chemical precipitate
Tagging for destruction: mark free pathogens, attract other cells to destroy them

Question 18

What kind of cell makes antibodies?

Answer 18

Plasma cells

Question 19

What is the primary response in antibody-mediated response?

Answer 19

first exposure to an antigen is slow
several weeks before antibodies reach their peak concentration
In the meantime symptoms can get worse, even death depending on pathogen strength

Question 20

What is the secondary response in antibody-mediated response?

Answer 20

second or later exposures to antigen, memory cells can respond quickly, powerfully
within a few days
May not even have symptoms upon 2nd and later exposures

Question 21

What is the difference between active and passive immunity?

Answer 21

Active Immunity occurs when antibodies are made actively by memory cells, present as long as memory cells intact
natural- due to infection with pathogen
artificial – vaccines with attenuated pathogens
Passive Immunity occurs when antibodies are put into the body without memory cells, gone when supply is gone.
natural – breastmilk, IgA
artificial – serum injection

Question 22

How do T-cells recognize self vs other?

Answer 22

MHC proteins on cell surface signify “Self”

Antigens displayed via “Antigen Presenting Cells”

Question 23

What are the 3 types of T-cells?

Answer 23

Cytotoxic T-Cells (CD8)
Helper T-Cells (CD4)
Regulatory T-Cells (CD4-25)

Question 24

What is a dendritic cell? Significance?

Answer 24

Dendritic cells are specialized macrophages that engulf pathogens
Pathogen broken down into antigens in the lysosome, then an MHC II protein is used to display pathogen on cell surface
Dendritic Cell is now an Antigen Presenting Cell (APC)

Question 25

What are the 2 types of MHC proteins?

Answer 25

MHC-I shows the cell is self; can show that self is infected

MHC-II only on antigen presenting cell= pathogen found and identified

Question 26

How do cytotoxic T-cells work?

Answer 26

also called CD8 cells, recognize body cells infected by pathogens by binding to MHC I-self-antigen complexes
Cytotoxic T-cells will then destroy infected body cells by lysis, or granzymes that induce apoptosis

Question 27

What do helper T-cells do?

Answer 27

Look for MHC-II (antigen-presenting cell), then mount immune response, trigger immune system to react to the antigen, in general
** Work with surveillance cells to activate immune response

Question 28

What do regulatory T-cells do?

Answer 28

also known as CD4-25 inhibit innate and adaptive immune responses to keep the system in check

Question 29

What is a Type-1 immediate hypersensitivity?

Answer 29

IgE reaction, “allergy”, atopy, can be local or systemic response
CD4 cells respond to allergen presentation, mast cells release histamine, inflammatory mediators
ex: peanut allergy, animal dander allergy

Question 30

What is a type-II cytotoxic hypersensitivity?

Answer 30

antigens within cell membrane
triggers cell destruction, phagocytosis
ex: drug reaction, transfusion reaction

Question 31

What is a type III immune complex disorder?

Answer 31

antigen-Ig complex deposits in tissues – antigen may be unknown
organ, joint dysfunction
ex: systemic lupus erythematosus, rheumatoid arthritis

Question 32

What is a type IV delayed hypersensitivity?

Answer 32

delayed T-cell response to antigen

ex: poison ivy, transplant reactions