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Adaptive Immune System – Cell Mediated Immunity - Coggle Diagram
Adaptive Immune System – Cell Mediated Immunity
2 types of adaptive immunity
Cell-mediated immunity (CMI) mediated by T cells via :
direct lysis
production of cytokine
Humoral-mediated immunity (HMI) mediated by
antibodies produced by B cells
antibodies bind with antigen
prevent infection
T-cell differentiation in thymus
T-cell precursors move from bone marrow to thymus in the
embryo in early life and develop in thymus
T-cells which are likely to attach the body itself are eliminated
in thymus – Central Tolerance
Mature T-cells are released into the blood
The thymus is large soon after birth but has greatly decreased
in size and function after puberty
Cells involved in adaptive immunity
B cells and T lymphocyte
B cells and T cells express
somatically generated antigen-specific receptor from the gene rearrangement process
T-cells develop in bone marrow and mature in thymus
They migrate to
peripheral lymphoid organs where they can be activated upon encounter
with foreign antigens
lymphocytes migrate to
secondary lymphoid organs
Mature naïve lymphocytes are continuously recirculating through these tissues,to which pathogen
antigens are carried
Naïve lymphocytes that do not
encounter with antigen leave through efferent lymphatic vessel
and return to blood
effector T cells
T helper (Th) cells (have CD4 marker)
Help B cells in making antibodies
(Th2)
Activate macrophages to kill
ingested organisms
Cytotoxic T lympohcytes (CTL) (have
CD8 marker
Directly kill infected cells (i.e virally
infected cells) or tumor cells
Antigen recognition by T cells
TCR does not recognize free antigens
TCR only recognize peptides from antigens which are processed by
APC and presented on MHC
ingredient
antigen
antigen processing for MHC class I
endogenous antigen
antigen processing for MHC class II
exogenous antigen
anitgen presenting cell (APC)
Professional APC are dendritic cells,
macrophages and B cells
Major histocompatibility complex (MHC)
MHC Class II
MHC Class I
mechanism of cell-mediated immunity
1st arm: attack on infected
cells (i.e CTL),activate infected
macrophages (ACP), activate
neutrophil response (increase
the barrier integrity, stimulate
isotope switching)
2nd arm: Stimulate
plasma cells and antibodies production
differentiation of naive T cell
Cytotoxic T cells (CTL)-MHC I
Most are CD8+
Kill host cells that are infected with viruses or bacteria
Die by apoptosis when stimulating antigen is gone
Recognize and kill cancer cells
Recognize and destroy transplanted tissues
helper T cells-MHC II
Most are CD4+
Recognize antigens on the surface of APCs
Once primed by APC antigen presentation, Th cells:
Stimulate proliferation of other T cells classes
Stimulate B cells to produce antibodies – Th2
Role of Th1 in clinical diseases
hypersensitivity
allergy (hypersensitivity)
Immune response to parasites i.e Helminth worm infection
Role of CD8 T cells in clinical diseases
kill tumor cell
kill virally infected cell
play crucial in graft rejection