Intro To The Immune System

Question 1

What is the most important physiological function of the immune system?

Answer 1

Prevent infections and eradicate established infections

Question 2

What antigens do B lymphocytes recognize and what are their effector functions? Are they adaptive or innate?

Answer 2

B lymphocytes: recognizes microbe

effector functions: 1) neutralize the microbe, 2) phagocytosis, and 3) complement activation, job is to make antibodies once activated

Adaptive

Question 3

What antigens do helper T lymphocytes recognize and what is their effector function? Are they adaptive or innate?

Answer 3

Helper t: recognizes microbial antigens presented by antigen-presenting cell

effector function: 1) activation of macrophages, 2) inflammation (cytokines), and 3) activation (proliferation and differentiation) of t and b lymphocytes, their job is to tell other cells what they should do and how they should do it

Adaptive

Question 4

What antigens do cytotoxic T lymphocytes (CTL) recognize and what is their effector function? Are they adaptive or innate?

Answer 4

CTLs recognize infected cells expressing microbial antigens

Effector function: kill the infected cell

Their job is to seek out infected cells and kill them, ALWAYS own cells, never microbe cells. Recognizes if there is something wrong with the cell and kills it

Adaptive

Question 5

What antigens do regulatory T lymphocytes recognize and what is their effector function? Are they adaptive or innate?

Answer 5

Don’t recognize antigens, their effector function is to suppress the immune system, job is to make sure IS doesn’t get out of hand, like the breaks on a car

Adaptive

Question 6

What antigens do Natural Killer cells recognize and what is their effector function? Adaptive or innate?

Answer 6

Innate cells so they don’t recognize antigens

Effector function: kill infected cells, they work with cytotoxic T lymphocytes, supplement CD8s

Question 7

What is the general purpose of the lymphoid system? What would happen if there were no lymph system?

Answer 7

Tissues and organs that bring B and T cells in contact with antigens, brings them to same place same time

If no lymph system, adaptive response wouldn’t work as well b/c things move too fast in circulatory system for them to come and stay in contact

Question 8

What does the lymph system include?

Answer 8

Lymphatic vessels
Primary (generative) lymphoid organs
Secondary (peripheral) lymphoid organs

Question 9

Explain the B and T cell maturation cycle.

Where do B cells mature? T cells?

Answer 9

B lymphocyte: common lymphoid precursor–> bone marrow–immature B lymphocytes–>blood/lymph– mature B lymphocytes–> circulate between blood, lymph, peripheral lymphoid organs (lymph nodes, spleen, mucosal and cutaneous lymphoid tissue)

T lymphocyte: common precursor–> thymus–(mature but naive)–> blood/lymph –(mature)–> circulate like B lymphocyte

B cell=bone marrow mature
T cell= starts in bone marrow as well, but matures in thymus

Question 10

What happens to most b and T cells?

Answer 10

Most never encounter their antigen or activate and they die, but we keep producing more and maintain the army

Question 11

Where are B cells found in lymph nodes?
What happens in the germinal center?
Where are T cells found?
Where does b and T cell communication take place?
What is in the medulla of the lymph node?
Where do lymphocytes enter the node?
How do antigens get in and out?

Answer 11

B cells are found in the follicles of the lymph node.
Germinal center: active B cell proliferation (surrounded by follicle)
T cells are found in the paracortex, which surrounds the follicles
B and T cell communication takes place in the interface between the paracortex and follicle
Macrophages are in the medulla (middle area)
They enter via the high endothelial venue.
Antigens get in and out via afferent and efferent vessels

Question 12

Where do blood infections go?

Where do tissue infections go?

Answer 12

Blood infection to spleen (spleen has no lymph drainage, it is just a blood filter)
Tissue infection to lymph node

Question 13

What happens in red pulp of spleen?
In white pulp?
What region is the B cell zone?
T cell zone?

Answer 13

Red pulp filters RBCs
White pulp deals with WBCs and is spotted with mini lymph nodes
B cell zone is the FOLLICLE
T cell zone is PALS (periarteriolar lymphoid sheath)

Question 14

Where is the greatest percent of immune tissue in the body? Where are these?

Answer 14

Mucosal-associated immune tissues (found under all mucosal tissue): digestive, respiratory, Spleen

Question 15

What are the three types of lymph tissue?

Answer 15

Spleen
Lymph node
Mucosal-associated

Question 16

Explain peyer’s patches and where b and T cells are found in them.

Answer 16

Peyer’s patches drain to mesenteric lymph node

They contain follicles (b cell zone) and T cell zone, and M cells

Question 17

What are M cells? (Pertaining to Mucosal-associated lymph). What do dendritic cells do in this part of the lymph system?

Answer 17

M cells are the gateway that allows things to pass through the mucosal epithelium layer and get into underlying tissue
Dendritic cells squirt through and grab onto things

Note: some nasty pathogens target m cells to gain access to the body

Question 18

Briefly explain the phases of immune response

Answer 18

1) 0 days: antigen recognition and innate response
2) 1 day: adaptive is activated and begins to build army (don’t see response till further along) naive T (via antigen presenting cell) and B cells (via microbe) are activated
3) 1-7: clonal expansion and differentiation (lymph nodes swell as army is built), by day 7 have effector cells army ready
4) 7-14: antigen elimination via humoral and cell-mediated immunity
5) 14+: contraction (homeostasis) where majority of t and B cells apoptose and memory (memory cells remain)
Remember: immunity does NOT go back to baseline b/c of memory immunity

At 7-10 start noticing response

Question 19

When would one notice serum sickness and why?

Answer 19

7-10 days after administration of antivenom because it is the adaptive response that reacts to the foreign antibodies

Question 20

Primary bs secondary immune response?

Answer 20

Primary: have no immunity, slower and weaker than secondary response, have memory cells after primary response

Secondary: faster and stronger than primary response because already have memory and adaptive response remembers what it has seen before, our antibodies get a little better each time we see the same antigens

Question 21

When everything works…? (4 things)

Answer 21

Protected against pathogens
Can fight off infection
Cancer cells are destroyed
Recognize and ignore harmless antigens (self and pollen or mutualistic organisms)

Question 22

What can happen when things go wrong?

Answer 22

Overly aggressive response
Chronic inflammation: lead to tissue and nerve damage

Responding when it shouldn't 
      Hypersensitivity
      Autoimmunity
      Transplant rejection
Not responding when it should 
      Immunodeficiency 
      Cancer

Question 23

What are hypersensitivity, autoimmunity, and transplant rejection?

Answer 23

Hypersensitivity: responding to harmless antigens (allergies)

Autoimmunity: responding to self antigens (usu genetic predisposition/environmental link)

Transplant rejection: not identical, treated as foreign