Lymphocyte Activation, Homing, and Trafficking Flashcards
what are the two classes of the major histocompatibility complex (MHC)?
MHC I and MHC II
how are antigens in tissue spaces presented to the Tc and Th cells?
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
how do T cells recognize the antigenic peptides presented by MHC molecules of dendritic cells?
the antigen receptors on T cells (TCRs)
what cells do MHC I molecules present antigens to?
Tc cells
what happens right after the antigen is recognized by the T cell?
activation and division (clonal expansion)
what does the dividing parent Tc or Th cell differentiate into?
effector Tc cells (cytotoxic T lymphocytes)
effector Th cells
long-lived memory Tc or Th cells
where can memory T cells generated in lymph nodes go? how long can they live?
anywhere except for mucosal associate lymphoid tissues
(secondary lymph organs okay, patrol organs and non-lymphoid tissues)
years
how do the cytotoxic T lymphocytes recognize the infected cells?
bind to the MHC I/antigenic peptide complex
infected cells express same antigenic peptide in conjunction with MHC I molecule
how do effector Th cells recognize the macrophages that have phagocytosed the microbe?
express same antigenic peptide in conjunction with MHC II molecule, which Th cells can recognize
what are follicular Th cells?
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
what happens to the effector Th and Tc cells after the antigen/pathogen is eliminated?
die by apoptosis
what is done with the small peptides of the antigen after it is endocytosed and processed by the B cells?
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
which professional antigen presenting cells are best at presenting antigens to naive T cells?
dendritic cells (efficient with naive and effector)
are macrophages and B cells more efficient at presenting antigens to naive T cells or effector T cells?
effector T cells
how does the effector follicular Th cell recognize the antigenic peptide presented to it by the MHC II molecules of the B cell?
TCRs
what does the B cell divide into with cytokine help from the T follicular cell?
plasma cells and long-lived memory B cells
where do memory B cells go after being generated in lymph nodes?
secondary lymphoid organs except mucosal associated lymphoid tissues
where do memory B cells go after being generated (what places specifically) and how long do they live in each place?
lymph nodes: a couple of weeks
spleen: couple of weeks to a few months
bone marrow: years (live and produce antibodies for)
how are antigens at mucosal surfaces transported to gut associated lymphoid tissues (GALT)?
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
do effector T and B lymphocytes generated in MALT get distributed to mucosal, non-mucosal sites, or both?
mucosal sites
what class of antibody do migrated plasma cells in mucosal sites mainly secrete?
IgA class of antibody
can plasma cells generated in MALT survive for a long time?
no, unlike those generated in spleen and lymph nodes
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
true
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
false
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
false: do not leave secondary lymph organs
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
true
if a response is generated in MALT, does it stay in MALT or go elsewhere?
elsewhere: goes to mucosal sites
do B cells present antigenic peptides efficiently to both naive and and effector T cells?
much better at effector T cells
can still present to both (like macrophages)
what lymphocytes live for years?
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)
what is transcytosis?
M cells taking up microbes/antigens, packaging them in vesicles to the basal membrane, where released into extracellular space
