Immune Response Flashcards
weapon immune system
1-cells that kill or ingest infect cell
2-soluble protein can neutralize/immobilize/kill pathigens
immunity kinds
1- innate immunity
2- adaptive immunity
innate is
non-specifc
adaptive involve
T and B cells
hematopoiesis
all bllod cells have limited life spans and need to be regenrated
RBC
erythrocytes
WBC
Leukocytes
blood cell generation
1- bone marrow produce hematopoietic stem cell
2- differentiate into myeloid cell and lymphoid cell
3- myeloid differentiate into WBC and RBC
4- Lymphoid differentiate into B/T/NK cells
two circulatory system
1- cardiovascular
2-lymphatic
interstitial fluid
1- by positive arterial pressure of heart pumping resulting loss of fluid from circulatory to interstitial spaces
2- interstitial fluid is three times the blood
3- interstitial fluid returned to heart by lympathic circulatory system
Lymphatic system facilitate
immune sytem migration and antigen transport from periphery to lymph nodes
how cell of immune sytem get into lymphatic system?
through special endothelial cells in lymph nodes
monocytes
from bone marrow
circulate in blood stream for 8 hrs
migrate into tissues and differentiate to macrophages
Differentiation of monocytes to macrophage
1- 5/10x enlargement in isze
2- increased complexity
3- increased phagocytic ability
macrophages lifespan
2-4 months
macrophage have many
receptors on its cell surface that recognize pathogen ssurfaces
PAMPS bind to
pattern recognition
Pathogens then are —- activating —-
phagocytosed
macrophage
binding bacteria to macrophage will
1- bactery degradation
2- inflammatory cytokines
macrophages remain —- until activating
in resting state
cytokines
substances secreted by immune system that effect on other cells
chemokines
type of cytokine with chemotaxis induction
after phagocyte of bacteria by macropphage
it digest pathigen and spit out most of degraded materials instead of some pieces in binding pocket of MHC
pieces in MHC binding pocket
present antigens to other cells of immune system
neutrophils
mosy abundant granulocyte
Store and released by bon emarrow and circulate in blood for 7-10 days
neutrophils function
kill pathogens
Leukocytosis
increase in number of neutrophils indicate infection
neutrophil killing mechanism
extracellular
intracellular
eosinophils
very small amount in blood system
activation release free radical and toxic granules
free radicals can
kill microorganism and parasite
during allergic response can cause tissue damage
basophils
extremly low level in circulation
basophils upon activation
release histamine can cause allergic reaction
dendritic cells
name due to long membrane extension
under most surface epithelia in heart and kidney
only cell arise from myeloid and lymphoid both
dendritic cells
dendritic cell function
engulf pathigens
migrate via afferent lymphatic vessels to regional lymph nodes, loose phagocitosis ability but gain ability to present antigens to t cellls
important link betwwen innate and adaptive immune sysytem
denderitic cell release antigen in lymph nodes for t cells
B cell antigen
membrane bound antigen
after activation secrete
T cell antigen
doesnot recognize free antigen
only can bind to antigen that is bound to MHC molecule
antigen
molecular fragment that is recognized by an antibody an B cell receptor or bind to MHC molecule
Epitope
is bound by antibody and rise MHC binding peptide
immunogen
antigen capable of invoking immune response
All antigens are immunogen?
false
Hepten
antigen yes
immunogen no
lymphocytes
released from bone marrow
circulate beetween blood and lymph
either will encounter antigen and differentiate or doesn’t encounter and apoptosis
B cells when activated differntiate to
Plasma cells that produce antibodies
antigen will be presented on B cell surface in context on class II MHC molecule
Professional antigen presenting cells
1- dendritic cells
2- macrophages
3- B-lymphocytes
**in order to present antigen should phagocytose
neutrophils can —- but cannot —-
can phagocytose
cannt present antigens
T cells
CD8+
CD4+
Regulatory
CD8
kill infected cell with virus
CD4
regulate other wbc
activate macrophage/B cell/CD8
Regulatory T cell
suppress other lymphocytes activity
MHC kind
class I: always associate woith CD8 and on every nucleated cell
class II: always associate with CD4 and only on professional antigen presenting cells
NK cells
circulate in blood as large lymphocytes with distinct cytotoxic granules
non-specific granulelfo
first line of defence is
nk cells
cells will undergo apoptosis
primary lymphoid tissue
1- bone marrow
2- thymus
all cell coming from —- stem cell from bone marrow
hematopoietic
b cell mature in
bone marrow
t cell mature in
thymus
innate response is
rapid
fixed
limited number of specifities
constant
min to hrs
adaptive response is
slow
variable
high specifities
improve during response
days
duration of t cell and b cell antibodies can be (memory B/T cells)
life long
complement
part of innate system
small proteins circulate in inactive mode
ultimate goal of them is destroy pathigen
complement pathway
1- pathogen recruiting by C1/C2/C4
2- cleavage C3 to C3a and C3b
3- C3b bound to surface pathogen
4- C3a recruit more phagocytes
cleavage of C3 will result in
1- opsonization(c3b)
2- recruitment inflammatory cells (c3a,c5a)
3- perforation pathogen membrane
4- from membrane attack complex – cell lysis (c5-c9)
Opsonization
by coatin ga phatogen makin g it easier to phagocyte
Adaptive immune response
ultimate goal: elimination by phagocytes
Antibodies:
1- bind and neutralize bacterial toxin
2- opsonization
3-activate complement (igG/IgM)
antibodies are secreted by —- and are —-
b cell
specific
antibodies are specific?
they tend to be specific as they have high affinity for the same virus if seen
what differentiate in defferent b cells
hyper variable region (HV=CDR)
tip of antigen bindign sites
Will every AA in HV region associate with antigen
no
both light and heavy chain has HV region and by different combination of them, different antigen can bind
antigen binding site
3 light chain
3 heavy chain
multiple weak non-covalent interaction
6 CDR will make an stable interaction
five classes of antibody based on their heavy chain
IgG
IgD
IgE
IgM
iGa
mature b cells express
IgM and IgD receptors
it will differentiate in lymph nodes
B class switch will happen in
bone marrow
monoclonal antibody
5 epitotes all are the same specifity
polyclonal antibody
5 different monoclonal epitote
in response to a complex antigen ——– will produced
polyclonal antiserum
if b cell encounter antigen
initiallt secrete IgM
then in lymphoid centers by increasing affinity can produce memory/IgG/IgA/IgE
During B cell development
V (variable)
D (diversity)
J (joining)
cut and respliced by DNA recombination
DNA recombination of VDJ is
Somatic recombination
B cells will helped by T cells to become fully activated and undergo
1- somatic hypermutation
2- affinity maturation
affinity maturation
select for mutated B cell having highest affinity for antigen
orhanization and arrangement of light and heavy chains will take place in —-
bone marrow
in bone marrow b cells that are —— are eliminated
recognize by self antigen
IgM
first antibody on B cell surface
produced by primary antibody response
after IgM, other antibodies with —– will respond with —
higher affinity
higher concentration
secondary stimulus when seen
higher affinity antibody will work faster and sooner
postulates of clonal selection
1- single type of receptor has unique specifity
2- high affinity connection of foreign molecule and lymphocyte receptor leads to lymphocyte activation
3- identical specificity daughter cell with original cell
4- prevent auto-immunity
clonal selection
many lymphocytes
removal of self-reactive lymphocyte
foreign antigen bind with a mature lymphocyte
differentiation and clonal expansion of effector cells
T cells in entering the thymus does not express
CD4/CD8 specificity
mature in thymus
self-antigens are eliminated
t cell only activate when
Recognize antigen presented on surface of MHC protein
T cell recognition
1- the apoptosis recognized by T cells are buried inside
2- antigen must first broken down into peptide fragments
3- epitope binds to MHC protein
4- t cell bind complex of mhc and epitope
MHC class I recognized by
CD8+
MHC class II recognized by
CD4+
Dendritic cells presenting antigen are recognized by
both CD8 and CD4
MHC molecules
in HUman called HLA
3 HLA come from each parents (total 6)
every MHC molecule can bind
wide variety of peptide antigens
if T-cell cannot identify the antigen within MHC protein context,..
no response
naive B cells
B cell that have not seen B cell
naive b cell will transform to
plasma cells
high rate Ig secretion
in plasma cell
dendritic cell
take up bacteria at site of injury and move to lymph node and settle in T cell area
present antigen to T cell via binding with MHC
target cell can be
virus-infected cell
macrophage
B cell
CD8 will kill directly the
virus - infected cell
CD4 will
1- activate macrophage (cytokines)
2- Chnage B cell to plasma cell (release antibody)
B cell activation
1- surface Ig capture anto\igen
2- complex internalized
3- complex destroyed and T-cell epitope presented by MHC class II
4- CD4 will identify MHC-epitope complex
5- B cell dissociate to plasma cell and IgM (or class switch recombination-other Ig)
in TCR-MHC interaction
Both T-helper and B-cell are bound to epitope
what happen in dark zone
clonal expansion
somatic hypermutation
what happen in light zpone
improved affinity
TCL_MHC interaction
IgM and plasma cell
activation of CD8+
1- recognition of antigen (additional signalling happen)
2- proliferation: increase in number
3- differentiation: acquire special function
4- effector function: kill apoptosis
why only infected cell are eliminated
progammed efficiently to eliminate
NEcrosis
1-chromatin clumping swollen organelles
2-disintegration
3-release intracelellular content
4-inflammation
Apoptosis
1- Segregation of cytoplasm
2- Nuclear fragmentation
3- phagocytosis
