Lymphocyte Activation, Homing, and Trafficking

Question 1

what are the two classes of the major histocompatibility complex (MHC)?

Answer 1

MHC I and MHC II

Question 2

how are antigens in tissue spaces presented to the Tc and Th cells?

Answer 2

engulfed by dendritic cells and brought to the draining lymph nodes
small peptides from the antigens are loaded onto MHC I and MHC II molecules of the dendritic cells to be presented

Question 3

how do T cells recognize the antigenic peptides presented by MHC molecules of dendritic cells?

Answer 3

the antigen receptors on T cells (TCRs)

Question 4

what cells do MHC I molecules present antigens to?

Answer 4

Tc cells

Question 5

what happens right after the antigen is recognized by the T cell?

Answer 5

activation and division (clonal expansion)

Question 6

what does the dividing parent Tc or Th cell differentiate into?

Answer 6

effector Tc cells (cytotoxic T lymphocytes)
effector Th cells
long-lived memory Tc or Th cells

Question 7

where can memory T cells generated in lymph nodes go? how long can they live?

Answer 7

anywhere except for mucosal associate lymphoid tissues
(secondary lymph organs okay, patrol organs and non-lymphoid tissues)
years

Question 8

how do the cytotoxic T lymphocytes recognize the infected cells?

Answer 8

bind to the MHC I/antigenic peptide complex
infected cells express same antigenic peptide in conjunction with MHC I molecule

Question 9

how do effector Th cells recognize the macrophages that have phagocytosed the microbe?

Answer 9

express same antigenic peptide in conjunction with MHC II molecule, which Th cells can recognize

Question 10

what are follicular Th cells?

Answer 10

effector Th cells that move to lymphoid follicles to help B cells: release cytokines to help B cells with proliferation, differentiation, class switching, antibody affinity maturation, and memory B cells formation

Question 11

what happens to the effector Th and Tc cells after the antigen/pathogen is eliminated?

Answer 11

die by apoptosis

Question 12

what is done with the small peptides of the antigen after it is endocytosed and processed by the B cells?

Answer 12

they are loaded onto the class II major histocompatibility complex (MHC II) and trafficked to the cell surface to be presented to the peptide-specific Th cell

Question 13

which professional antigen presenting cells are best at presenting antigens to naive T cells?

Answer 13

dendritic cells (efficient with naive and effector)

Question 14

are macrophages and B cells more efficient at presenting antigens to naive T cells or effector T cells?

Answer 14

effector T cells

Question 15

how does the effector follicular Th cell recognize the antigenic peptide presented to it by the MHC II molecules of the B cell?

Answer 15

TCRs

Question 16

what does the B cell divide into with cytokine help from the T follicular cell?

Answer 16

plasma cells and long-lived memory B cells

Question 17

where do memory B cells go after being generated in lymph nodes?

Answer 17

secondary lymphoid organs except mucosal associated lymphoid tissues

Question 18

where do memory B cells go after being generated (what places specifically) and how long do they live in each place?

Answer 18

lymph nodes: a couple of weeks
spleen: couple of weeks to a few months
bone marrow: years (live and produce antibodies for)

Question 19

how are antigens at mucosal surfaces transported to gut associated lymphoid tissues (GALT)?

Answer 19

M (microfold) cells in follicle associated epithelium (FAE) via transcytosis (engulf but do not kill, then transport out)
dendritic cells take up antigen and present to T cells
B cells also pick up and present to follicular Th cells

Question 20

do effector T and B lymphocytes generated in MALT get distributed to mucosal, non-mucosal sites, or both?

Answer 20

mucosal sites

Question 21

what class of antibody do migrated plasma cells in mucosal sites mainly secrete?

Answer 21

IgA class of antibody

Question 22

can plasma cells generated in MALT survive for a long time?

Answer 22

no, unlike those generated in spleen and lymph nodes

Question 23

true/false: s. aureus-specific Th cell response develops in the draining lymph nodes, and the effector Th cells migrate to the inflamed skill where they produce cytokines, which help macrophages with killing of the pathogen

Answer 23

true

Question 24

true/false: s. aureus-specific Th cell response develops in the draining lymph nodes, ad the memory Th cells can migrate to the inflamed skin and to other non-mucosal organs, such as the non-inflamed liver

Answer 24

false

Question 25

true/false: s. aureus-specific B cell response develops in the draining lymph nodes, and some of the specific plasma cells migrate to the inflamed skin where they produce antibodies, which contribute to eliminating the pathogen by the phagocytes

Answer 25

false: do not leave secondary lymph organs

Question 26

true/false: s. aureus-specific B cell response develops in the draining lymph nodes. some of the specific plasma cells migrate to the spleen where they produce antibodies. the antibodies via blood enter the skin and contribute to eliminating the pathogen by the phagocytes

Answer 26

true

Question 27

if a response is generated in MALT, does it stay in MALT or go elsewhere?

Answer 27

elsewhere: goes to mucosal sites

Question 28

do B cells present antigenic peptides efficiently to both naive and and effector T cells?

Answer 28

much better at effector T cells
can still present to both (like macrophages)

Question 29

what lymphocytes live for years?

Answer 29

memory T cells (not effector Th or Tc cells)
plasma cells in bone marrow (those in spleen and lymph nodes do not live long)
memory B cells generated in MALT (can survive anywhere in body) (not plasma cells)

Question 30

what is transcytosis?

Answer 30

M cells taking up microbes/antigens, packaging them in vesicles to the basal membrane, where released into extracellular space