Introduction to the Immune system pt II Flashcards
What parts of the innate immune system do we expect to be functioning within the first 6 hours of an infection?
phagocytes, complement, physical barriers
What parts of the innate immune system do we expect to be functioning within the first 12 hours of an infection?
phagocytes, complement, physical barriers, and NK cells
How long does it take for lymphocytes to undergo proliferation in response to an APC or a pathogen?
4 days
How long does it take for antibodies and effector cells to be produced by effector cells?
around 7 days
How long does an adaptive immune response take?
from days to weeks?
Humoral response is
extracellular and uses Abs
Cell mediate response is
intracellular and uses T cell-APC interactions
“generative lymphoid organs” include
thymus and bone marrow
“peripheral lymphoid organs” include
lymph nodes, spleen, mucosal/cutaneous lymphoid tissues
All B lymphocytes develop from ____ during ____ of the ____
precursors formed allthrough the life of the person
All T lymphocytes are generated in the ____ during the _____
thymus during the fetal stage
BCRs are what, and what do they recognize?
B cell receptors
they recognize carbohydrates, proteins, lipids, and nucleic acids
Plasma cells do what
effector cells of B cell lineage: produce antibodies
Abs are secreted where?
into circulation and in the mucosal tissue
what do Abs do?
neutralize and eliminate extracellular microbes and microbial toxins
name the “3 big” things about Abs
they neutralize, eliminate, immobilize pathogens
What do T cell’s recognize, and with what?
peptides in primary formation only
What are the two kinds of T cells and what are their traits?
Helper T cells (which express CD4)
What do helper T cells do?
they can activate macrophages, initiate inflammation, stimulate proliferation/differentiation of B/T lymphocytes
What do cytotoxic T cells do?
directly kill infected cells
How do T cells activate macs?
IFN-gamma
What are the “3” steps involved in antigen capture for an APC?
1) capture
2) processing
3) presenting Ags
Professional APCs include
MOs, dendritic cells, B cells
Non-professional APCs include
all nucleated cells in the body except the above listed
What do professional APCs activate?
both helper T cells and cytotoxic lymphocytes
what do non-professional APCs activate?
only cytotoxic lymphocytes
what happens to the non-professional APC after infection and interaction with a CTL?
they are directly destroyed
Blood born versus epithelial pathogens
epithelial pathogens are phagocytised in the epithelia, where they are then transported to a lymph node to display to a T cell
blood born pathogens are carried through the circulatory system to the spleen to be presented
the lymph node captures antigens from the
epithelium and connective tissues
the spleen captures antigens from the
blood
passage of an Ag in the lymph through/to the lymph node
APC cell (dendrites) carries Ag through lymph system through Afferent lymphatic vessels to the T cell zones, where they present to T cells
free-floating Ags are delivered to the B cell zones in the cortex
Two ways Ag can be delivered to the lymph node:
free floating and via dendrite
explain
APCs deliver Ag to T cells
free floating Ags delivered to B cells
PALs consist of what cells
BOTH the immediate T cells around the artery and the B cells a little further out
white pulp =
T cells surrounding artery and lymphoid follicles
MHC complexes: what are they
I and II
class I MHC is expressed by all nonprofessional APCs class II MHC is expressed by all professional APCs
who recognizes which mhc class?
Th cells express CD4; rec MHC II and MHC 1
CTLs express CD; rec MHC 1
which cells express MHC, BCRs, and TCRs?
MO and DCs express MHC class I and II
T cells express class I MHC but not class II or BCRs
B cells express both MHC I and II, BCR but no TCR
Granulocytes express Class I MHC
Erythrocytes do express anything
the TCR has two grooves: what for?
one is for the polymorphic region of the MHC molecule
one is for the residue of the peptide being presented
the MHC has one pocket, one structural peg, and an informal peg
the informal is the peptide being carried to the TCR
the formal is a polymorphic region that interacts with the TCR
there is a binding groove for the “anchoring” residue
peptides bind to MHC molecules how?
by anchor residues
Class I MHC Ag presentation pathway
what kinds of ags
to whom are they presented
NB!
who expresses them
Intracellular pathogen molecules
CTLs “only”
MHC I will never be “empty” of an Ag if expressed
all nucleated non-professional cells
Class II MHC Ag presentation pathway
only expressed by professional APCs
MOs, dendritic cells, B cells
microbial Ags are taken up by phagocytosis and endocytosis. who does what
macrophages phagocytize; B cells and dendritics take up via endocytosis
to whom are Ag-loaded MHC II cells taken?
Th
Phases of Adaptive Response (5)
1) Ag recognition –> Ag recognized
2) Lymphocyte activation –> clonal expansion AND differentiation into effector T lymphocytes/Plasma cells
3) Effector phase –> humoral/cell mediate response –> elimination of antigens
4) Decline (homeostasis) –> apoptosis
5) memory –> surviving cells
how does the immune response decline?
as Ag presence declines, apoptosis of effectors increases
