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What is adaptive immunity?
-The body's abilitiy to recognize and defend itself against distince invaders and their products
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What are the five attributes of adaptive immunity?
- -Specificity
- -Inducibility
- -Colonality
- -Unresponsiveness to self (tolerance)
- -Memory
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What are the two types of adaptive immune response?
- -Humoral immue responses
- -Cell-mediated immune responses
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What are the two main types of lymphocytes in adaptive immunity?
- -B lympocytes (B cells)
- -T lymphocytes (t Cells)
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What is an overview of adpative immunity?
- There is a T Helper cell that will either
- 1. Tell B cells to release antibodies
- 2 Use cytokines to get T cytotoxic cells to work
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What is the lymph system?
- -Lymphatic vessels, cells, tissues, and organs that screen the tissues of the body for foreign antigens.
- -The flow of lymph, one-way system that conducts lymph from tissues and returns it to the circulatory system
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What is lymph?
- -Liquid with similar comnposition to blood plasma
- -Arises from fluid leaked from blood vessels into surrounding tissues
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What are the primary organs of the lymphatic system?
- -Red bone marrow
- -Thymus
- Where cells undergo maturation
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What are secondary lymph organs?
- -Where matured cells reside and function
- -Lymph nodes
- -Spleen
- -Tonsils
- -Mucosa-Associated lymphatic tissue (MALT)
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What are lymph nodes?
- -Small, bean- shaped structures in the body that are part of the lymph system.
- -Found singly or in groups, may be small or large.
- -Can be felt in neck, groin, and underarms
- -When a part of the body is infected, nearby lymph nodes can be swollen
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What are properites of antigens?
- -Molecules that the body recognizes as foreign and worthy of attack
- -Recognized by 3D regions called epitopes (8 amino acid long)
- -Include bacterial components, proteins of virus, fungi, and protozoa
- -Food and dust have antigenic particles
- -Antigens provoke a specific immune response
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What are Exogenous antigens?
- -Antigens that have entered the body from the outside, by inhalation, ingestion, or injection
- -These are broken up or presented to T cells
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What are endogenous antigens?
- -Antigens that have been generatedc within previously normal cells as a result of normal cell metabolism or because of viral or intracellular bacterial infection.
- -Virus has non cell antigen
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What is a autoantigen?
Usuallly a normal protein or complex of proteins
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What is a pluripotent stem cell?
-When cells of blood orginate from one common stem cell
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What are B cells?
- -Arise and mature in red bone marrow
- -Found in spleen, lymph nodes, and MALT
- -Small % circulate in blood
- -Major function is secretion of antibodies
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What is a BCR?
- -B-cell receptor, has specificity.
- -Each B cell generates a single BCR
- -Two variable regions of teh BCR form the antigen-binding sites
- -The entire repertoire of an individuals BCRs is capable of recognizing millions of different epitopes.
- -Grabs the antigen
- -Has a constant area and variable is where antigen is attached, and is attached to the cell
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What happens when a B cell gets stimulated?
-The antigen stimulates a B cell and it releases immunoglobulins.
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What is the shape of an antibody?
-Y shape, with a variable area for antigens to attach and then a costant middle.
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What are antibodies?
- -Specificity
- -Antibodes are immunoglobulins similar to BCRS
- -Secreted by activated B cells called plasma cells
- -Have identifcal antigen-binding sites and antigen specificty as the BCR does
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What is the function of an antibody?
- -Antigen-binding sites are complementary to epitopes (lock and key)
- 6 functions:
- 1. Activation of complement and inflammation
- 2. Neutralization
- 3. Opsonization- the sauce, better for PMN to get
- 4. Agglutination- clumping
- 5. Killing by oxidation
- 6. Antibody-dependent cellular cytotoxicity (ADCC) NK cells kill easier with coating
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How does a flu shot work?
By neutralization so it cant bind to cells
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What is important about the classes of antibodies?
- -threats confronting the immune system are variable
- -Class involved in immune response depends on the type of antigen, portal of entry, and antibody function needed.
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What are the five classes of antibodies?
-IgM, IgG, IgE, IgA, IgD
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What is IgM?
- First antibody produced
- Largest
- Pentameric (five)
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What is IgG
- -Most common and longest-lasting antibody
- -in serum
- -Can cross the placenta because its the smallest
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What is IgA?
- Associate with body secretions
- Dimeric
- Protective secretions
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What is IgE?
Involved in reponse to parasitic infections and allergies
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What is IgD?
-Exact function not known
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What is a T Cell?
- Produced in bone marrow, but matures in Thymus
- Only about 4/100 are mature
- -Circulate in the lymph and blood and migrate to lymph nodes, spleen, and peyer's patches
- -Antigen-binding sites are complementary to epitopes
- -Have T cell receptors (TCR) on their cytoplasmic membrane.
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What is a naive T cell?
-one that has not incountered any antigen
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What is a TCR?
- T cell receptor
- -Does not bind directly to the antigen
- -Specificity
- -Does not recognize epitopes directly
- Oly bind epitops associated with a MCH protein
- -Act against cells that harbor intracellular pathogens
- -Cannot get secreted
- -Shape is like two poles with variable then a constant regions, made of carbs, and a disulfide bond
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What is a APC?
Antigen presenting cell
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How does APC work?
The APc stimulates T cells to become helper cell, which stimulates B cells and uses cytokines to get help from T cytotoxic cell
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How do you type T lymphocytes?
- Based on surface glycoproteins and characteristic functions
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What are the three types of T lymphocytes?
- Cytotoxic, Helper, and regulatory
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What is a cytotoxic T cell?
- -Directly kills other cells (virally infected cells)
- -CD8+
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What is a helper T cell?
Helps regulate the activates of B cells and cytotoxic t cells
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What is a regulatory T cell?
Represses adaptive immune responses
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What is the clonal selection theory?
Induction of a certain antigen which causes proliferation and leads to effector memory
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What is the clonal deletion of auto-reactive B cells?
- -It is vital that immune response not be directed against autoantigen
- -Body elimiantes self-reactive lymphocytes
- -The immature B cells whose BCR bind too strongly to self antigens, will not mature
- -If B cells are found to be highly reactive to self they are idcued to undergo apoptosis
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What is the clonal deletion of auto-reactive T cells in thymus?
During maturation in the thymus, T cells that react to autoantigens are eliminated by being induced to undergo apoptosis
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What are cytokines?
- -Cells of immune system communicate by releasing soluble regulatory proteins that act on other cells
- -Secreted by various leukocytes
- -The complex web of signals among all the cells of teh immune system is called cytokine network
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What are interleukins (ILs)?
- Cytokine of the immune system
- -Signal among leukocytes
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What are Interferons (IFNs)?
- Cytokine of the immune system
- -Antiviral proteins that may act as cytokines
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What are growth factors?
- Cytokine of the immune system
- -Proteins that stimulate stem cells to divide
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What are Tumor necrosis factor (TNF)?
- Cytokine of the immune system
- -Secreted by macrophages and T cells to kill tumor cells and regulate immune responses and inflammation
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What are chemokines?
- Cytokine of the immune system
- Chemotactic cytokines that singal leukocytes to move
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Does each cell have a different receptor for different cytokines? and can it produce more than one type of cytokine?
Yes and yes
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What is the Major Histocompatibility complex?
- -MHC
- -Group of antigens 1st identified in graft patients
- -Important for determining compatiability of tissues for tissue grafting
- -Major histocompatibility antigens are glycoproteins found in the membranes of most cells of vertebrate animals
- -Hold and postion antigenic determinants for presentation to T cells
- Antigens bind in the groove of MHC molecules
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What is MHC Class 1?
- Present on the surface of all nucleated cells in the body
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What is MHC class II?
-Present on the surface of all professional antigen presenting cells aka macrophages
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What are examples of profesional antigen presenting cells?
-Dendritic cells, macrophages and B cells
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What are dendritic cells?
- -Antigen that enters the skin is loaded on dendritic cells, which migrate to draing lymph nodes. In the lymph nodes, naive T cells are activated by antien-loaded dendrici cells and start to proliferate and differentiate
- -These antigen-responisve cells acquire expression of specific adhesion molecules and chemokine receptors that enable them to migrate to the effector site.
- -On all CT graft, sees the antigen and presents to T cell
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What is antigen processing?
- -Antigens processed for MHC proteins to dispaly epitopes
- -Different processes for endogenous and exogenous antigens
- Endogenous- MHC I
- Exogenous- MHC II
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What is cell-mediated immune response?
- -Reespond to intracellular pathogens and abnormal body cells
- -Most common is intracellular pathogens are viruses
- -The response is also effective against cancer cells, intracellualr protozoa, and intracellular bacteria.
- -The cell is infected, expresses virus antigen, T cell comes and kills that cell
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What is the activation of T cell clones?
- -Cytotoxic T cells
- -Antigen presentation by APC MHC II
- -Helper T cell differentiation
- -Clonal expansion- IL-2R
- -Self-stimulation
- MHC I
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What is cytoxic lymphocytes serial killing?
-Kills virally infected cells. T cell recognizes by epitopes, after MHC I, then caues infected cell to apoptosis and macrophages clean up the mess
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What are memory t cells?
- -Some activated T cells become memory T cells
- -Persist for months or years in lympoid tissue
- -immediately functional upon subsequent contacts with epitope specific to its TCR
- -Ex. vaccinations
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What is a humoral immune response?
- -Against exogenous pathogens
- -Is activation of B cells which release Immunoglobulins
- -T dependent and T indenpendent of B cells
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What is T dependent activation of B cells/
- -B and T cells that have not yet recognized an antigen via their BCR/TCR are called naive lymphocyes
- -Most protein antigens that activate naive B cells are called T dependent antigens. The B must first interact with effector T4 lymphocytes before they have a response
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What happens after the T4 is presented to the B cell?
- -It relaese cytokines that actiate B cells to proliferate into antibody-secreting B cells and plasma cells
- -Some B cells differentiate into B memory cells for heightened 2nd response against antigen
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What are plasma cells?
- -Majority of cells produced during B cell proliferation
- -Only secrete antibody molecules complementary to the specific antigen
- -Short lived cells that die within a few days of activation-their antidies and progeny can persist
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What are memory B cells?
- - T depedent
- -Immunological memory
- -Produced by B cell proliferation but no not secrete antibodies
- -Have BCRS complementrary to teh antigenic determinatnt that triggered production
- -Long lived cells that persist in lymph tissue
- -Initiates antibody production if antigen is encountered again
- -Form at first exposure
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What is the binding of T-independent antigen by a B cell?
- -t independent antigens are antigens which can directly stimulate B cells to produce antibody without T cell hep in general.
- -Polysaccharides are T-independent antigens
- -These antigens are characterized by the same antigenic determinant repeated many times (has same epitope)
- -Faster response
- -This is lacking in children, so do not give them polysacchoride vaccine
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What is a primary response?
- IgM then after 5 days IgG goes up then back down after 15 days
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What is a secondary response?
-IgM and IgG both high on day 3, IgM goes downn day 6, but IgG stays high because of memory B cells
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What is acquired immunity?
-Specific immunity acquired during an individuals life
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What are two types of acquired immunity?
- -Naturally: response against antigens encountered in daily life
- -Artifically: response to antigens introduced via vaccine
- Can be active or passive (antibodies from antoehr indiviudal animal or human)
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