Imin Review Flashcards
thymocytes
immature T cells
- after hematopoiesis, thymocytes enter thymus = proliferation & development
DiGeorge’s syndrome
partial thymus or no development at all
T or F. A selection process eliminates non-reactive or self-reactive B cells just as T cells are eliminated in the thymus
T! This occurs in the bone marrow
describe the follicles of the lymph nodes
primary:
- clusters of resting B cells
- some dendritic cells
secondary:
- B cells responding to antigens seen by (pale) germinal centre; surrounded by resting B cells, Th cells, macrophages and dendritic cells
high endothelial cells in lymph nodes
cuboidal or columnar venules (HEVs)
allow activated T and B cells to enter lymph through surface receptors via diapedesis
this traps antigens from blood stream and facilitates immune response
spleen
the red pulp in the spleen
sinusoids rich in RBCs and macs
old RBCs and blood-borne pathogens removed by phagocytosis
white pulp in spleen
T, B cells, and macs made up of PALS (periarteriolar lymphoid sheath); T cells that surround arterioles
marginal zone of the spleen
interface between red pulp and white pulp rich in lymphocytes and macrophages
MALT
tonsils
crypts
Peyer’s patches
M cells
tonsils
lingual, platine, pharyngeal
trap microbes in nasopharynx
crypts
fenestrated epithelium to allow pathogens in oral cavity to contact lymphocytes and macrophages
Peyer’s Patches
located in submucosa of small intestine
contains primary and secondary follicles
specialized epithelial cells that transfer antign from lumen to T, B cells and macrophages beneath
M cells
BALT
bronchus-associated lymphoid tissue
- lymph aggregated adjacent to bronchi
these defensive barriers have low pH to suppress bacterial growth
stomach
sebum
urogenital tract
this is produced by virus-infected cells that induce antiviral state in neighbouring cells
interferon
the first responders
neutrophils
secretes TNF!
live only 1-4d
these cells are part of the innate and adaptive immune system
monocytes/macrophages (some tissue-specific = Kupffer, histiocytes, etc.)
- phagocytose, secrete TNF
- antigen presentation
phagocytic cells have receptors for the following:
- cytokines (INF-y)
- complement + components (C3a, C5a)
- formyl methionine (f-met) peptides produced by organisms, mannose, LPS
what happens when lysosomes fuse with phagosomes
phagolysosome = killing occurs
= pH decreases, lysozyme released, defensins (porin forming peptides)
reactive nitrate intermediates are toxic and include:
nitrogen dioxide
nitrous acid (HNO2) = longer lasting
NK Cells CD markers
CD16+ 56+
3-
mechanism of action of NK cells
direct killing of infected cells decreased or no MHC I
antibody-dependent cellular cytotoxicity (ADCC)
activates macrophages through INF-y
how can NK Cells directly kill? (2)
- perforin: helps target cell take up granzyme through pore formation in vesicle membrane
- granzyme B: activates caspase in target cell to induce apoptosis
programmed cell death in NK Cells
Fas Ligand n NK binds Fas receptor on target cell; apoptosis!
target recognition of NK cells
- activating receptors: CELLS WILL SHOW SIGNS OF STRESS
- inhibitory receptors: binds self MHC I = NK will leave it alone
how does ADCC occur?
NK cells have receptors for Fc portion of Abs; kill by antibody-dependent cell-mediated cytotoxicity
role of INF-y produced by NK cells
activate macrophages to enhance killing
also has anti-viral properties (decrease viral replication in cells)
what do macrophages release after engulfing microorganisms that signal to NK cells to release INF-y?
IL-12
define extravasation
chemokines: IL-8, C5a, C3a attract neuts to come to tissue
selctins
glycoproteins on leukocytes and endothelial cells that bind glycosylated proteins (MUCIN) on both leukocytes and endothelium
allows neuts to roll along endothelium
define integrins
proteins made up of a and B subunit that bind ICAMs
integrins change confirmation due to chemoattractants (______) to provide greater affinity to ICAMs on endothelial cells
IL-8, C3a, C5a
two types of inflammation
localized and systemic
what plays a part in systemic inflammation?
acute phase reactants
- CRP
- fibrinogen
- haptoglobin, etc
CTL markers
CD3+ CD8+
induction
naive CD8+ cells (in lymphoid tissues) recognize viral peptides in MHC I
T cell expansion & differentiation into effector cells occurs in lymphoid tissue
