Intro to Immunity Flashcards
Protection of one organism against another, elimination or control of the offending organism, and setting up conditions to prevent the offending organism from causing more problems
Immunity
Network of many different types of proteins, cells, tissues, and organs
Immune System
What are two major roles of the immune system?
Combating pathogens and combating cancer
Disease causing organisms such as bacteria, viruses, fungus, parasites, and prions
Pathogens
Aberrant, uncontrolled cell growth gene mutations
Cancer
Proteins that can specifically bind pathogens
-immune system can made a trillions
Detectors
The main question that the immune system must answer is, is this cell/tissue/protein
Self or not self
Uninfected, healthy, normal
Self
Viruses, bacteria, fungus, parasites, and cells that are infected by these pathogens and diseased cells (i.e. cancer)
Non-self
The destruction of healthy tissues, leading to nasty diseases
Autoimmunity
What is an example of autoimmunity?
Type 1 diabetes
Attack and kill insulin producing B cells resulting in type 1 diabetes
T cells
The term antigen is derived form which two words?
Antibody and generator
Most antigens are
Proteins or large polysaccharides
Often a component of invading microbes, such as the capsule, cell wall, flagella, toxin
Antigens
An antigen elicits an immune response it is often referred to as a
Immunogen
The reactive portion of the antigen that reacts chemically with an antibody to form the antigen-antibody complex or immune complex
Epitope
Not all antigens are derived from
Pathogens
Overexpressed, miss-expressed or mutated proteins can be antigens in
Cancer
Antigens found in autologous tumor Tumor cells can express altered versions of normal proteins due to
Genetic mutations
Bind to distinct antigen epitopes
Antibodies
The portion of the antibody that is different for every antibody
Variable regions
Antibodies are made up of
Heavy chains and light chains
Antigen binds to a region of the antibody formed from the association of the
Variable light (VL) chain and variable heavy (VH) chain
Antibodies are the secreted version of the
B cell antigen receptor (BCR)
Have an overall structure that is similar to the BCR
T cell antigen receptor (TCR)
The TCR is NOT secreted like an
Antibody
The antigen binding site is highly variable on a
TCR
There are trillions of different
TCRs
TCR and BCR genes are generated by
V to J somatic recombination
What are the two types of immunological tolerance?
Central tolerance and peripheral tolerance
Removal of self reactive clones
Central tolerance
Occurs in the thymus (T cells) and bone marrow (B cells)
Central Tolerance
Composed of ignorance, anergy, and suppression
Peripheral tolerance
Hide your self antigens
Ignorance
Shut down the self reactive clones
Anergy
Use other molecules, proteins or cells to keep the self reactive clones in check
Suppression
Effector T cells and antibodies persist for weeks after exposure to antigen. This is called
Protective immunity
The second exposure to the same antigen produces a
Much faster response
This faster second response is referred to as
Immunological memory
Part of the circulatory system, comprising a network of conduits called lymphatic vessels that carry a clear fluid called lymph
Lymphatic System
There are tissues and organs that are designed and located to convey antigens into contact with
Lymphocytes
Before returning to circulation, lymph is filtered by
Lymph nodes
What are the three types of cells that lymph contains?
T cells, B cells, and dendritic cells
Primary sites for immune system activation
Lymph nodes and spleen
Cells of the immune system develop from a common progenitor called the
Hematopoetic stem cell
B cells develop in the
Bone marrow
Develop in the thymus
T cells
Cell membrane molecules that are used to classify leukocytes into subsets
Cluster of Differentiation (CD)
Defined or classified by the reference monoclonal antibodies to which they bind
CD molecules
There are many clusters of differentiation; many cells express more than one
CD marker
A phenotypic characterization of a cell of hematopoietic origin may be made by examining the pattern of
CD markers
Following maturity, migrate to various lymphoid organs where they await contact with antigens
T lymphocytes (T Cells)
The basis for cell-mediated immunity q
T cells
Can kill infected cells or can help activate other cells (B cells and macrophages)
T cells
Antibody producing cells that respond to an antigen stimulation (humeral response)
B lymphocytes (B cells)
Can provide protective immunity for decades
Antibodies
Develop in bone marrow, but specific functions are often acquired later within tissues
Macrophages and dendritic cells
Have differing microscopic appearances but they are grouped together as the mononuclear phagocytic system
Macrophages and Dendritic cells
Macrophages and dendritic cells have a variety of functions including phagocytosis, secretion of cytokines, and
Antigen presentation
Cells must be “tagged” as infected to activate the
Adaptive immune system
This “tag” is a
MHC bound to fragments of antigen
MHC class I antigens are targeted to
CD8 T cells (Killer T cells)
MHC class II antigens are targeted to
CD4 T cells (Helper T cells)
Pathogen detector expressed by T cells
TCR
The most important Antigen Presenting Cells (APC) are
Dendritic Cells (DCs)
Can directly kill virus-infected cells or can help the immune defense capabilities of other cells
T cells
Loaded with peptides taken up by phagocytosis
MHC II
Loaded with peptides made inside the cell
MH I
Capable of destroying other cells, particularly viruses-infected cells and tumor cells
-do not express TCR or BCR
Natural Killer Cells
Natural Killer cells do not express
TCR or BCR
Natural killer cells an attack
Large parasites
Defend the body against antigens and pathogens in body fluids
B cells
B cells defend the body against antigens and pathogens in body fluids. This process is called
Humoral Immunity
Defend the body against abnormal cells and pathogens inside living cells
T cells
T cells defend the body against abnormal cells and pathogens inside living cells. This process is called
Cell-mediated Immunity
Function in nonspecific immunity such as that seen with bacteria entering a wound
Phagocytes
Have phagocytic receptors that bind microbes and their components
Macrophages
Bound material is then internalized in phagosomes and broken down into
Phagolysosomes
Will not activate the immune response. They must be mixed with adjuvants
“Clean” Pathogens
An agent that stimulates the immune system and, for example increases the response to a vaccine, but does not have a specific antigenic effect in of itself
Adjuvant
Components of the pathogens are recognized by
Pattern recognition receptors
Germline encoded receptors that bind pathogen specific antigens, such as LPS
Adjuvants
Activation via these receptors precedes activation of the
Adaptive immune response (T and B cells)
Required for innate defense against fungal infection in flies
Toll
Toll-like receptors (TLRs) recognize
Pathogens
How can we test blood to separate CD4, CD8, and other immune components
Fluorescence Activated Cell Sorting (FACS) i.e. flow cytometry
The basis for the smallpox vaccine is that smollpox viruses share some surface antigens with
Cowpox
Immunization with cowpox induces antibodies against
Cowpox surface antigens
Cowpox antibodies are then able to bind and neutralize
Smallpox virus
