Immune System Part 2

Question 1

Specific (Adaptive) Immunity

Answer 1

Can recognize and remember specific pathogens

-Ability to mount stronger attacks each time the pathogen is encountered

Question 2

Antigens

Answer 2

Foreign molecules (proteins or polysaccharides) from pathogens

• Stimulate immune system directly or
• Processed and presented to immune system by APCs

Question 3

B Lymphocytes

Answer 3

Produce and release antibodies into plasma to act at a distance

• Mature in bone marrow
• Confer humoral immunity
• Antigen binding to a B cell receptor activates cloning

Question 4

T Lymphocytes

Answer 4

Antibodies remain bound to cell to destroy pathogens upon contact

• Mature in thymus
• Cell-mediated defense: bacteria, viruses, parasites, fungi, abnormal cells
• Activated by antigen bound to MHC molecule
• Can’t respond to antigen directly

Question 5

B Lymphocytes Memory Cells

Answer 5

Formed during primary immune response, needed for secondary immune response

• Long lived, inactive close
• Respond rapidly to subsequent attack

Question 6

B Lymphocytes Plasma Cells

Answer 6

Produce and release antibodies

• initial immune response lifespan is 3-4 days
• Following affinity maturation lifespan is years, cells continue to secrete high levels of antibodies

Question 7

CD4 Cells (T lymphocyte)

Answer 7

Activated by MHC class II

• Produce memory cells and helper cells
• Helper cells stimulate other immune cells (CD8, macrophages, B cells, nonspecific WBCs) by secreting cytokines

Question 8

CD8 Cells (T lymphocyte)

Answer 8

Activated by MHC class I

• Produce memory and cytotoxic cells
• Cytotoxic cells kill abnormal cells
• Perforin creates holes in target cells
• Granzymes signal apoptosis

Question 9

Suppressor (Regulatory) T cells

Answer 9

CD4+/CD25+/FoxP3+

• Inhibit excessive immune response
• Reduce inflammation

Question 10

Natural Killer T cells (NK-T cells)

Answer 10

Recognize glycolipid antigen presented by CD1d

-Can perform functions of either helper or cytotoxic t cells

Question 11

Positive Selection

Answer 11

Ensures immune response

• Cells that bind MHC/antigen complex w/ adequate affinity receive vital survival signal
• Cells w/ inadequate affinity die via apoptosis

Question 12

Negative Selection

Answer 12

Prevents autoimmune response

-Cells that interact strongly w/ self-antigen receive apoptosis signal

Question 13

Off Switch for T cells

Answer 13

After infection has been removed
-Producing and secreting FAS ligand, which binds back in an autocrine manner to the FAS receptor on T cells causing apoptosis

Question 14

Lymphokine

Answer 14

Cytokine specific for subsets of lymphocytes

Question 15

Interleukin 1 (IL-1)

Answer 15

Induces fever
Induce proliferation and activation of lymphocytes
Increase number of bone marrow cells
Cause degeneration of bone joints

Question 16

IL-2

Answer 16

Produced by helper T cells

-Activate cytotoxic T cells especially during microbial infection

Question 17

IL-4

Answer 17

Produced by helper T cells

• Activates B and T cell proliferation
• Differentiation of CD4 T cells into helper T cells (that can make more IL4)
• Induces B cell glass switching to IgE
• Up-regulates MHC class II production

Question 18

IL-5

Answer 18

Produced by helper T cells and mast cells

• Stimulate cell growth
• Increase immunoglobin secretion, key mediator in eosinophil activation, associated w/ allergic diseases

Question 19

IL-10

Answer 19

Produced by monocytes, lymphocytes, and mast cells

-Anti-inflammatory that counteracts inflammation in allergic reactions

Question 20

IL-12

Answer 20

Produced by dendritic cells, macrophages, and Blymphoblastoid cells in response to antigenic stimulation
-Involved in differentiation of naive T cells into helper T cells

Question 21

MHC Markers

Answer 21

Recognition of normal self tissues

• HLA
• Class 1 and Class 2

Question 22

Class I MCH

Answer 22

On almost every cell in body except RBCs

Activation of cytotoxic T cells

Question 23

Class II MCH

Answer 23

On B cells and APCs

• Presents antigens to lymphocytes
• Activation of Helper T cells

Question 24

Antibody structure

Answer 24

2 heavy chains joined with disulfide bond and 2 light chains
-variable region at top and constant region below it

Question 25

1. Fab fragment
2. Fab2 fragment
3. Fc fragment

Answer 25

1. variable region
2. every but lowest constant portion
3. constant portion of both chains

Question 26

IgM

Answer 26

1st antibody produced
-membrane bound 
-allow helper t recognition
-Primary antibody against A and B antigens on RBCs
-Large pentameter 
5-15%

Question 27

IgG

Answer 27

Target antigen tagged cell for destruction (“Goodbye cell”)
-Primarily in secondary immune response
-Equal in blood and tissue
-Can cross the placenta providing passive immunity
80%

Question 28

IgA

Answer 28

In external secretions
-prevents pathogen entry across mucus membranes
10-15%

Question 29

IgE

Answer 29

Allergic response

<1%

Question 30

IgD

Answer 30

Signals B cell activation

<1%

Question 31

Antibody Generation (VDJ)

Answer 31

VDJ recombination of variable region

• Segment of of DNA b/w D and J region gets removed and deleted
• Segment of DNA b/w V and DJ gets removed and deleted

Question 32

Somatic Hypermutation (SHM)

Answer 32

• Antibody generation
• Programmed process of mutation in variable regions
• C becomes U
• Mutations repaired by DNA mismatch repair enzymes
• Error prone DNA polymerase fill gap and create mutations

Question 33

Antibody Generation (Class Switching)

Answer 33

• Happens in constant region
• Allows dif daughter cells from same B cell produce antibodies of dif isotypes or subtypes
• Requires genetic recombo event