L14 Adaptive Immunity

Question 1

Characteristics of adaptive immunity

Answer 1

Highly specific
Immunologic memory
Rapid response to second antigen exposure

Question 2

What are the types of active immunity and describe them

Answer 2

Natural:state of resistance following contact with foreign antigen (clinical or subclinical infection)
Artificial: through killed or attenuated organisms by vaccine

Question 3

What are the types of passive immunity and describe them

Answer 3

Natural: through placenta(igG)
Breastfeeding(igA)lasts 4-6 months
Artificial: administration of preformed abs (antitoxin when illness is attributable to exotoxins) eg botulism

Question 4

What are the cells involved in specific immune response and what do they do

Answer 4

Macrophages:phagocytic cells—-APC
T lymphocytes: intracellular microbes
B lymphocytes: humoral immunity

Question 5

What are the subsets of t cells and their function

Answer 5

CD4 effector cells: th1,th2,th17
Can become t reg cells if exposed to TGF-B (suppress t cell responses)
CD8 positive cells: effector cytotoxic t cells, kill infected host cells as virus infected or tumor cells by delivery of toxic granule content(perforin and granulysin)

Question 6

What do b cells carry on their surface and what is their function

Answer 6

IgM act as receptors for a specific antigen

Question 7

Immunity directed at extraceullar pathogens

Answer 7

Humoral immunity

Question 8

Immunity depending on intracellular pathogens

Answer 8

Cell mediated immunity

Question 9

Describe the process of antigen presentation

Answer 9

Proteins are internalized by apcs
Undergo partial proteolysis or denaturation
Peptide fragments become expressed on surface of APC as MHC complex
Recognized by specific t cell

Question 10

Examples of APC

Answer 10

Macrophages
Langergans cells of the skin
Dendritic cells
B lymphocytes

Question 11

What are the 3 signals needed for t cell activation

Answer 11

1-t cell receptor interacts with an MHC peptide complex on APC
2-co stimulation: b7 protein on APC binds with CD28 on t cell
3-cytokines delivered by APC

Question 12

Th-1 cells

Answer 12

Stimulated by intracellular pathogens

Secrete IL-2 and IFN-y

Question 13

What does IL-2 do and IFN-y

Answer 13

IL-2 acts on CD8 cells and enhances their proliferation and differentiation
IFN-y amplifies th-1 response and activates macrophages

Question 14

Th-2 cells

Answer 14

Activated in response to large extracellular pathogens
Produce IL4 ,5,13
Promotes humoral immunity+causes class switching

Question 15

Th17 cells

Answer 15

Against fungal infection

Question 16

Describe t cell dependent activation of b cells

Answer 16

B cells recognize their specific ag by surface membrane ig receptors
Act as APC and ingest large proteins and digest them—display MHC ll molecules for recognition by t helper cells
T helper cells secrete cytokines to activate b cells
Class switch after proliferation
Memory cells

Question 17

Describe t cell independent b cell activation

Answer 17

Polysaccharides,lipopolysaccharides and lipids= t cell independent antigens
Contain multiple identical epitopes that cross link ig receptors on b cell providing signals that stimulate b cell responses
Dominated by IgM production
Short lived plasma cells
No memory cells

Question 18

How are t cytotoxic cells activated

Answer 18

When they recognize their antigen on the surface of a target cell along with MHC class l mol
Also by effect of cytokines (IL2)
Kill viral infected and tumor cells

Question 19

What is the primary response

Answer 19

Ab produced after first encounter with pathogen
Serum conc rises for several weeks and then declines
First IgM then IgG and IgA
IgM declines before IgG

Question 20

What is the secondary response

Answer 20

More rapid
Generates higher levels than primary response
Due to presence of memory cells 
IgM is same
IgG is more and persists longer

Question 21

Describe the interaction between innate and adaptive immunity

Answer 21

▪️Phagocytic cells process and display antigens to facilitate stimulation of specific t lymphocytes
▪️Macrophages secrete cytokines that help trigger the initiation of specific immune responses
▪️t cells produce cytokines(IFN-y) which enhance microbicidal activities of phagocytes
▪️ab produced by plasma cells bind to pathogens and assist with phagocytosis and ab dependent cell mediated cytotoxicity