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Adaptive Immunity: Lecture 3 (Clone Detection of B cells (occurs in bone…
Adaptive Immunity: Lecture 3
Skin grafting
type of surgery to transplant of skin and tissue
MHC describes protein production and genes
has an anti-binding groove
lies between 2 polypeptides to make it up
class 1
found on cytoplasmic membrane of all human cells except blood cells
regulate present antigens
class 2
made of macrophages, dendritic cells, b cells
dendritic are long thin cytoplasmic process called dendrites
phagosome cells are found under skin and mucus membrane and some extend between skin or through mucus membrane
they collect antigens and move to nodes to interact with cells
Professional APC
cytoplasmic membrane have thousands of MHC 2 molecules
bind may thousands different epitopes because not specific
some won't meaning it won't cause immune response
the molecules determine which epitopes might trigger a response
Antigen processing
2 different types
Endogenous process
epitopes of polypeptide move into the E.R. and bind in complement antigen-binding grooves
E.R membrane now loads and is packaged fro golgi body and vesicle
vesicle membrane fuses with cytoplasmic membrane
cell displays MHC 1 protein on cell surface
every nucleated cell makes class 1 and allows detection at cells antigen
Exogenous process
only dendritic cells process
lysosome in membrane fuses phagosome binding antigens
vesicle fuses with cytoplasmic membrane
leads to leave MHC 2 epitope complex on surface
empty MHC 2 molecules are not stable on surface and degrades as a result
T cells
act against intracellular pathogen and act against antigens
adult red bone marrow produces T cells
chemotactic molecules attract T cells from vessels to thymus where it adheres to adhesive chemicals and molecules signals
random choices and combine segments of DNA from TCR to create new gene combo specific to that cell code for a unique TCR
TCR
Each T cell has a TCR
binds to unique epitope
TCR complementary to every possible epitope in environment but will only encounter some
Lymphocytes
Cytotoxic T cells
distinguish by copy of TCR
directly kill infection cells with pathogen or abnormal cells
have CD8 glycoproteins
Helper T cells
identified by presence of CD4 glycoproteins found on cell cytoplasmic membrane
function to help regulate activity of B cells and cytotoxic T cells during response
provide necessary signals
Type 1
assist cytotoxic T cells and stimulate and regulate innate immunity
type 2
function with B cells
they both secrete cytokines to regulate entire system
Regulatory T cells
identified by presence of CD4 and CD20 proteins
secrete cytokines different from secreted by helper T cells
suppress immune response and promote tolerance of certain antigens
Clone Detection of B cells
occurs in bone marrow
prevents B cells from attacking autoantigens by destroying BCR's
Step 1. stem cells in RBM generate a host of B cells
Step 2. B cells random and have BCR with particular shape
Step 3. cells with BCR complementary to an autoantigen bind and stimulate cell death
Step 4. with non complementary BCr is released into blood
Cytokines
soluble proteins secreted by certain cells to act as messengers
the system cytokines have almost identical functions
network
complex web of signals among all types in system
interleukins
send signals among leukocytes
Inerferon's
stop spread of viral infections
functions as cytokines too
most important is gamma
Growth factors
stimulate leukocytes stem cells
ensure body is supplied with wbc's
body control immune response by limiting them
Tumor Necrosis Factor
secreted by macrophages and T cells
kills tumor cells
regulate response and inflammation
Chemokines
signal wbc to move toward them
call to site of inflammation or infection; called chemotaxis