B Cells 7

Question 1

what is the difference btwn the primary and secondary response in terms of IgM?

Answer 1

MOST make IgM in primary response, SOME memory B cells make IgM

Question 2

what is the difference btwn the primary and secondary response in terms of somatic hypermutation?

Answer 2

in primary response, SOME B cells will go to germinal center to undergo somatic hypermutation

in secondary reponse, MOST memory B cells express IgG and undergo further somatic hypermutation

Question 3

repeated immunization leads to: (3)

Answer 3

1. increasing affinity of Abs via SHM and affinity maturation, will re-enter the germinal center each time
2. class-switching
3. higher levels of MHC II and B7

Question 4

what is the importance of memory B cells having higher levels of MHC II and B7 than naive B cells? (2)

Answer 4

1. helps memory B cells acquire and present Ag more efficiently to T_FH than naive B cells –> more efficient class-switching
2. increases Ab production

Question 5

where do memory B cells go?

Answer 5

they circulate in blood and end up in spleen and LN as they wait for the antigen

Question 6

what are the 2 types of memory T cells

Answer 6

1. T_CM cells –> central memory T cells
2. T_EM cells –> effector memory T cells

Question 7

where are T_CM cells located?

Answer 7

reside in/travel between secondary lymphoid tissue to find their match on APC

Question 8

what allows T_CM to be reactivated?

Answer 8

rapidly reactivated by second Ag exposure

Question 9

how do cytokines affect T_CM?

Answer 9

cytokines cause them to differentiate into diff subsets

Question 10

where are T_EM cells located?

Answer 10

travel to/between tertiary tissues in the periphery

Question 11

what is the general purpose of T_EM cells?

Answer 11

contribute better to first-line defenses

Question 12

what happens to memory T cells upon second Ag exposure?

Answer 12

shift right back into effector functions –> no need for strong co-stimulatory signals or cytokines

Question 13

how do we identify memory T cells?

Answer 13

not as easy to identify like B cells in blood, but can identify in vivo based on immune response

Question 14

what are the 3 characteristics of memory T cells?

Answer 14

1. long-lived
2. phenotypically unique
3. functionally different

Question 15

what does it mean for memory T cells to be phenotypically unique?

Answer 15

closer to effector T cells than naive T cells

Question 16

what does it mean for memory T cells to be functionally different?

Answer 16

less requirements for activation and express a unique set of receptors

still require contact with p:MHC but less sensitive to restimulation

Question 17

when do memory T cells become effector T cells?

Answer 17

upon reactivation

Question 18

how does the memory response vary for diff people?

Answer 18

may have diff individual responses but 2nd response is always larger

Question 19

what is passive immunity?

Answer 19

temporary adaptive immunity due to transfer of immune products (Ab - antiserum) from immune individual –> nonimmune individual

Question 20

what does the immune system do in passive immunity?

Answer 20

nothing

Question 21

what is active immunity?

Answer 21

adaptive immunity induced by natural exposure to pathogen or by vaccination

Question 22

what are 2 examples of passive immunity?

Answer 22

1. monoclonal therapy
2. breastmilk

Question 23

when is passive immunity good? 3 examples

Answer 23

provides a preformed antibody which is good when your immune system cannot defend itself:

1. immune deficiency
2. toxin or venom with immediate threat to life
3. exposure to pathogen that can cause death faster than an effective immune response can develop

Question 24

why is the protection from passive immunization temporary?

Answer 24

does not activate the host’s natural immune response

Question 25

what happens when Ab are passively transferred to a non-immunized animal?

Answer 25

PREVENTS activation of naive B cells –> no memory

Question 26

why do we not vaccinate newborns?

Answer 26

Ab they acquired from placenta and breastmilk will kill off the vaccine and don’t activate naive B cells –> then when they get infected, it will be like first response

Question 27

what is the original antigenic sin?

Answer 27

once we have an effected response, memory cells will be used instead of activating naive cells that target new, unique epitopes

i.e. immune system gets trapped and unable to cause potentially more effective responses

Question 28

what does active immunization induce?

Answer 28

immunity and memory

Question 29

what are the 2 ways active immunity can be achieved?

Answer 29

1. natural exposure
2. artificial (vaccine)

Question 30

what are vaccines?

Answer 30

use altered, non-dangerous form or component of infectious agent to induce specific immune response with memory

Question 31

what type of cells are induced by active immunization?

Answer 31

B cells and T cells

Question 32

what are adjuvants?

Answer 32

chemicals included in vaccines to ENHANCE the immune response

Question 33

what are 3 ways to enhance the immune response if the Ag is a weak stimulator?

Answer 33

1. promote inflammation to recruit more immune cells
2. slow down Ag release to promote longer interactions
3. adjuvants

Question 34

what are attenuated vaccines?

Answer 34

virus has multiple mutations that prevent it from causing a productive infection in IMMUNOCOMPETENT humans

have a built-in adjuvant –> PAMPs from virus trigger immune response

Question 35

what is herd immunity?

Answer 35

when majority of the population is immune to an infectious agent, the pathogen reservoir is reduced due to the low chance of a susceptible individual contacting an infected individual