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Immune System Basics. Immunity: The capacity to resist infectious pathogens. Pathogens: Disease-causing organisms Self vs. Non-self recognition Major Histocompatibility Complex (MHC 1) Antigen- a particle or piece of pathogen an immune system recognizes as foreign. MHC 1. Antigens. - PowerPoint PPT Presentation
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Immune System BasicsImmune System Basics Immunity: The capacity to resist
infectious pathogens. Pathogens: Disease-causing
organisms Self vs. Non-self recognition Major Histocompatibility
Complex (MHC 1) Antigen- a particle or piece of
pathogen an immune system recognizes as foreign.
Immunity: The capacity to resist infectious pathogens.
Pathogens: Disease-causing organisms
Self vs. Non-self recognition Major Histocompatibility
Complex (MHC 1) Antigen- a particle or piece of
pathogen an immune system recognizes as foreign.
MH
C
1
Antigens
1st Defense:Non-specific Immune System
1st Defense:Non-specific Immune System
Reacts immediately after infection- does not need to ID pathogen.1. Barrier Defenses: Skin and Mucous membranes2. Inflammatory Defenses:
Histamine is released at the sign of damage Blood vessels leak fluid and WBC’s
3. Cellular and Molecular Defenses:1. Macrophages: Use pocket transport (phagocytosis) to destroy foreign
particles.2. Natural Killer Cells (NK): Release hydrolytic enzymes onto target cells
to rupture/destroy them. 3. Interferon4. Complement
Reacts immediately after infection- does not need to ID pathogen.1. Barrier Defenses: Skin and Mucous membranes2. Inflammatory Defenses:
Histamine is released at the sign of damage Blood vessels leak fluid and WBC’s
3. Cellular and Molecular Defenses:1. Macrophages: Use pocket transport (phagocytosis) to destroy foreign
particles.2. Natural Killer Cells (NK): Release hydrolytic enzymes onto target cells
to rupture/destroy them. 3. Interferon4. Complement
QuickTime™ and a decompressor
are needed to see this picture.
Final Defense: Specific Immune System
Final Defense: Specific Immune System
Recognizes pathogens and develops a sustained immune response.
Comprised of two parts:1. Cell- Mediated Response2. Humoral ResponseWhite blood cells characters (lymphocytes):Macrophage
Helper T cells (Th)
Killer T cells (Tc)B cells
Recognizes pathogens and develops a sustained immune response.
Comprised of two parts:1. Cell- Mediated Response2. Humoral ResponseWhite blood cells characters (lymphocytes):Macrophage
Helper T cells (Th)
Killer T cells (Tc)B cells
Specific Immunity- The Battle Begins!
Specific Immunity- The Battle Begins!
Macrophages search body tissues for pathogens. Consume pathogens with phagocytosis, kill it with
lysosomes, and save the antigens. Antigens placed into MHC 2 receptors and
displayed on macrophage’s membrane. The macrophage is now considered an antigen-
presenting cell (APC). http://www.youtube.com/watch?v=eVLO6j6Ho64
Macrophages search body tissues for pathogens. Consume pathogens with phagocytosis, kill it with
lysosomes, and save the antigens. Antigens placed into MHC 2 receptors and
displayed on macrophage’s membrane. The macrophage is now considered an antigen-
presenting cell (APC). http://www.youtube.com/watch?v=eVLO6j6Ho64
QuickTime™ and a decompressor
are needed to see this picture.
Specific Immunity Cont.Specific Immunity Cont. Macrophage chemically signals Helper T to attach to it. Helper T attaches to the MHC 2 receptor (with foreign
antigen stuck in it) with its CD4 receptor. Helper T cells have incredible variety of receptors that act
like a “lock and key” in regards to the displayed antigen. If the Helper T’s “key” fits the displayed antigen’s “lock”,
the Helper T is activated. Activation results in Helper T releasing cytokines (ex.
Interleukin)- chemicals that cause lymphocytes to start mitosis.
Macrophage chemically signals Helper T to attach to it. Helper T attaches to the MHC 2 receptor (with foreign
antigen stuck in it) with its CD4 receptor. Helper T cells have incredible variety of receptors that act
like a “lock and key” in regards to the displayed antigen. If the Helper T’s “key” fits the displayed antigen’s “lock”,
the Helper T is activated. Activation results in Helper T releasing cytokines (ex.
Interleukin)- chemicals that cause lymphocytes to start mitosis.
Fig. 43-17
Antigen-presentingcell
Peptide antigen
Cell-mediatedimmunity (attack on
infected cells)
Class II MHC moleculeCD4
TCR (T cell receptor)
Helper T cell
Humoralimmunity
(secretion ofantibodies byplasma cells) Cytotoxic T cell
Cytokines
B cell
Bacterium
+
+ +
+
Cell-Mediated ResponseSeek and Destroy
Cell-Mediated ResponseSeek and Destroy
Body cells can be infected by viruses that will hide inside the cell.
As the virus reproduces inside cells, pieces of it fall off and are put into new MHC 1 receptors that the cell puts on its own membrane.
Killer T cells can bind to an infected cell’s MHC 1 receptors with their CD8 receptors.
If Killer T binds to MHC 1 receptors with antigen attached, it releases a chemical called perforin.
Perforin ruptures the infected cells membrane and exposes the virus to other immune cells. http://www.youtube.com/watch?v=1tBOmG0QMbA&feature=related
Body cells can be infected by viruses that will hide inside the cell.
As the virus reproduces inside cells, pieces of it fall off and are put into new MHC 1 receptors that the cell puts on its own membrane.
Killer T cells can bind to an infected cell’s MHC 1 receptors with their CD8 receptors.
If Killer T binds to MHC 1 receptors with antigen attached, it releases a chemical called perforin.
Perforin ruptures the infected cells membrane and exposes the virus to other immune cells. http://www.youtube.com/watch?v=1tBOmG0QMbA&feature=related
QuickTime™ and a decompressor
are needed to see this picture.
Fig. 43-11
Antigen
Top view: binding surfaceexposed to antigen receptors
Plasmamembrane ofinfected cell
AntigenClass I MHCmolecule
Fig. 43-18-3
Cytotoxic T cell
Perforin
Granzymes
TCRCD8
Class I MHCmolecule
Targetcell
Peptideantigen
Pore
Released cytotoxic T cell
Dying target cell
Fig. 43-12
Infected cell
Antigenfragment
Class I MHCmolecule
T cellreceptor
(a)
Antigenassociateswith MHCmolecule
T cellrecognizescombination
Cytotoxic T cell (b) Helper T cell
T cellreceptor
Class II MHCmolecule
Antigenfragment
Antigen-presentingcell
Microbe
1
11
2
22
Humoral SystemBring in the artillery!
Humoral SystemBring in the artillery!
B cells have receptors called antibodies (100,000/cell).
Different B cells have uniquely shaped antibodies that match specific antigens.
If a B cell’s antibody is able to bind with a specific antigen (lock and key effect), the B cell receives a message from Helper T’s to become activated.
Activated B cells divide into Plasma B and Memory B cells.
http://www.youtube.com/watch?v=iDYL4x1Q6uU&feature=related
B cells have receptors called antibodies (100,000/cell).
Different B cells have uniquely shaped antibodies that match specific antigens.
If a B cell’s antibody is able to bind with a specific antigen (lock and key effect), the B cell receives a message from Helper T’s to become activated.
Activated B cells divide into Plasma B and Memory B cells.
http://www.youtube.com/watch?v=iDYL4x1Q6uU&feature=related
QuickTime™ and a decompressor
are needed to see this picture.
Humoral System Cont.Humoral System Cont.
Plasma B cells produce and secrete 10,000 “keyed” antibodies per hour.
Due to their shape, each can bind to several antigens at once.
Antigen/Antibody binding has three effects. Neutralization Macrophage signaling Complement pore formation http://www.youtube.com/watch?v=lrYlZJiuf18&feature=fvw
Plasma B cells produce and secrete 10,000 “keyed” antibodies per hour.
Due to their shape, each can bind to several antigens at once.
Antigen/Antibody binding has three effects. Neutralization Macrophage signaling Complement pore formation http://www.youtube.com/watch?v=lrYlZJiuf18&feature=fvw
QuickTime™ and a decompressor
are needed to see this picture.
Fig. 43-21
Viral neutralization
Virus
Opsonization
Bacterium
Macrophage
Activation of complement system and pore formation
Complement proteins
Formation ofmembraneattack complex
Flow of waterand ions
Pore
Foreigncell
Memory B cellsMemory B cells
These cells do not actively produce antibodies Instead, they remain in the bloodstream and
maintain their cell life cycle independently from Th commands.
If the same pathogen/antigen complex presents itself in the future, these cells are already activated and ready to produce antibodies.
There are also Memory versions of Th and Tc cells that serve a similar function.
These cells do not actively produce antibodies Instead, they remain in the bloodstream and
maintain their cell life cycle independently from Th commands.
If the same pathogen/antigen complex presents itself in the future, these cells are already activated and ready to produce antibodies.
There are also Memory versions of Th and Tc cells that serve a similar function.