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Inflammation is Non-specific response.
Local signs and symptoms include
Redness
Pain
Heat
Swelling
Possible loss of function
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Inflammation has three stages, what are they?
- Vasodilation and increased permeability
- Emigration of phagocytes from the blood into the interstitial space
- Tissue repair
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The redness and heat are due to the _______ blood flow. The swelling is because of the _______ vascular permeability. The cytokines and inflammatory chemicals, released as part of _______, target free nerve ending that result in the perception of _____.
increased; increased; inflammation; pain
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A substance that is recognized as foreign and reacts with product of immune system is an
antigen
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There are four main characteristics that determine the antigenicity of substance:
recognition as foreign, structural complexity, size organic in nature. Recognition as foreign is the most important of the three.
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If a molecule fits all of the criteria, except for size, it is referred to as a
hapten.
A hapten doesn't trigger an immune response, unless it binds to another molecule, now it is big enough
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If a pathogen is large enough, it may have multiple sites that can react with the immune system. These sites are called
antigenic determinants or epitopes
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The main players in adaptive immunity are the
lymphocytes
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Adaptive Immunity
T lymphocytes
- Produced in bone marrow, mature in thymus
- T-helper (CD4) sells
- T-cytotoxic (CD8) cells
- T-regulator cells
- Memory T-helper and T-cytotoxic cells
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Adaptive Immunity
B lymphocytes
- Produced and mature in the bone marrow
- Activated to become plasma cells
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Lymphocyte:
T-helper cells
What is their function?
The middle-man or main "helper" of the immune response. The T-helper cells will receive information from non-specific phagocytic cells and pass that information on to generate a specific response to a particular antigen. These are also called CD4 T-cells, due to the presence of the CD4 marker.
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Lymphocyte:
T-cytotoxic Cells
What is their function?
These T-cells destroy abnormal cells. Viral infected cells and cancerous cells are their main targets. These are also called CD8 T-cells
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Lymphocyte:
T-regulator cells
What is their function?
T-regulator cells keep the immune system from getting out of control. They decrease the reactivity of the other types of T-cells. This is essential for maintaining self-tolerance
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Lymphocyte:
Memory T-cytotoxic and Memory T-helper cells
What is their function?
Produced with an initial exposure to an antigen to provide memory of the event and a rapid-reponse if re-exposed to the antigen. Memory cells do not participate the first time around.
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What are the two types of adaptive immunity?
cell-mediated immunity
antibody-mediated immunity
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In cell mediated immunity, T-cytotoxic cells
are activated directly against abnormal cells, such as cancer cells or even tissue transplants.
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In antibody-mediated immunity, B-lymphocytes are
activated to become plasma cells, which produce and secrete specific antibodies
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Major histocompatibility complex (MHC) group of
genes that code for a group of trans-membrane proteins, also called human leukocyte antigens (HLA), on the surfaced of all nucleated cells
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MHC Molecules:
MHC class-I molecules
- Present on all body cells, except red blood cells
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MHC Molecules:
MHC class-II molecules
- Present on the surface of antigen-presenting cells (APC's)
- APC's have a primary responsibility to present antigen to other components of the immune system. (APC's are usually phagocytes, but B cells can be APC's)
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Cells that initially detect the antigen to present it to the rest of the immune system are called
antigen-presenting cells (APC)
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Antigen processing and presentation is required for
cell-mediated and antibody-mediated immunity
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APCs are commonly ________, but B cells can present _______.
phagocytes; antigen
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Antigen Presentation:
Once an antigen is processed, it is ready to meet the
middle-man, the T-helper cell.
- the T-helper cell, through a specific T-cell receptor will bind to the antigen fragment presented by the MHC-class molecule.
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Antigen Presentation:
Binding as well as cytokine stimulation results in the activation and proliferation of the
T-helper cell.
- Clonal selection- more T-helpers and T-memory cells
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An inactive T-helper, specific for the antigen, will bind with its T-cell receptor to the presented antigen on the APC. This will activated the T-cell. The activated T-cell will proliferate (increase its numbers) and differentiate (mature). This process is called
clonal selection
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T-Cytotoxic Activation:
Inactive T-cytotoxic cells bind to
abnormal cells presenting viral proteins or cancer proteins on MHC class-I molecule
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T-Cytotoxic Activation:
T-helper cells act as a
co-stimulator
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T-Cytotoxic Activation:
The T-cytotoxic cells will also undergo clonal selection
Increased T-cytotoxic cells and memory T-cytotoxic cells
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B-Cell Activation:
B-cells can be activated by direct recognition of antigen through B-cell
receptors and through T-helper cell activation.
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B-Cell Activation:
B-cells undergo clonal selection
- Activated to become plasma cells (Synthesis of antibodies)
- Produce B-memory cells
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Steps in Antigen Processing and Presentation:
Exogenous Antigens
- Ingestion of the antigen
- Digestion of the antigen into fragments
- Synthesis of MHC class-II molecules
- Vesicular packaging of class-II molecules
- Fusion of fragment and class-II vesicles
- Binding of fragments to class-II molecules
- Insertion of the antigen- MHC class-II complexes in the plasma membrane for recognition.
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Steps in Antigen Processing and Presentation:
Endogenous Antigens
- Digestion of the antigen into fragments
- Synthesis of MHC class-I molecules
- Binding of fragments to class-I molecules
- Vesicular packaging of class-I molecules
- Insertion of the antigen- MHC class-I complexes in the plasma membrane for recognition.
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