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136 Cards in this Set
- Front
- Back
Specific Immunity: Aka?
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- Third line of defense and is acquired.
- Dual system of B and T lymphocytes |
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Antigen?
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Molecules that stimulate a response by T and B cells
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2 Characteristics of Specific immunity
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1. Specificity
2. Memory |
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Specific Immunity: SPECIFICITY?
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Antibodies produced, function only against the antigen that they were produced in response to.
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Specific immunity: MEMORY?
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Lymphocytes are programmed to "recall" their first encounter with an antigen and respond rapidly to subsequent encounters.
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Types of immunity
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Active immunity
Passive immunity Natural immunity Artificial immunity |
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Active immunity
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Results when a person is challenged with antigen that stimulates production of antibodies; creates memory, takes time, and is lasting.
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Passive immunity
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Preformed antibodies are donated to an individual; does not create memory, acts immediately, and is short term
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Natural immunity
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Acquired as part of normal life experiences
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Artificial immunity
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Acquired through a medical procedure such as a vaccine
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Natural active immunity vs.
Natural passive immunity |
N. Active immunity -- Acquired upon infection and recovery
N. passive immunity -- acquired by a child through placenta and breast milk |
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Artificial active immunity vs. Artificial passive immunity
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A. active immunity - acquired through inoculation with a selected Ag
A. passive immunity - administration of a preparation containing specific antibodies |
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Overview of the Specific Immune Responses (5 things)
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1. Development and differentiation of the immune system
2. Lymphocytes and antigens 3. The challenge of B and T lymphocytes by antigens 4. B lymphocytes and the production and activities of antibodies 5. T-lymphocyte responses |
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Development of Response System
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- Cell receptors or markers confer specificity and identity of a cell
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Major functions of receptors are?
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1. To perceive and attach to nonself or foreign molecules
2. To promote the recognition of self molecules 3. To receive and transmit chemical messages among other cells of the system 4. To aid in cell development |
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Major Histocompatibility Complex (MHC)
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- Receptors found on all cels except RBCs
- Aka human leukocyte antigen - Plays a role in recognition of self by the immune system and in rejection of foreign tissue |
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Functions of MHC
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- Genes for MHC clustered in a multigene complex:
1. Class 1 - markers that display unique characteristics of self molecules and regulation of immune reactions; required for T lymphocytes 2. Class 2 - regulatory receptors found on macrophages, dendritic cells, and B cells |
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Lymphocyte Receptors (3 things)
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- Lymphocyte's role in surveillance and recognition is a fcxn of their receptors
- B-cell receptors: bind free antigens - T-cell receptors: bind processed antigens together with the MHC molecules on the cells that present antigens to them |
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B-cell receptors do what?
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Bind free antigens
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T-cell receptors do what?
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Bind processed antigens together with the MHC molecules on the cells that present antigens to them
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In bone marrow: Lymphocytic stem cells differentiate into ?
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Either T or B cells
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B cells stay where?
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Bone marrow
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T cells migrate to the ???
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Thymus
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Both T and B cells migrate to where?
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Secondary lymphoid tissue
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Lymphocyte is specifity is ??
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Preprogrammed.
Existing in the genetic makeup before an antigen has ever entered the system |
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Each genetically different type of lymphocyte expresses a ?
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Single specificity
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First introduction of each type of antigen into the immune system selects a ......?....... Causing ???
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A genetically distinct lymphocyte.
... Causing it to expand into a clone of cells that can react to that antigen. |
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Special categories of Antigens (4)
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Alloantigens
Superantigens Allergen Autoantigens |
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An alloantigen ?
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Cell surface markers and molecules that occur in some members of the same species but not in others
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Superantigens?
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Potent T cell stimulators; provoke an overwhelming response
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Allergen?
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Antigen that evokes allergic reactions
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Autoantigens?
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Molecules on self tissues for which tolerance is inadequate
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Table 15.1: Properties of B cells
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Site of grwth -- Bone marrow
Antigen surface marker -- Ig Circ in blood -- Low numbers Receptors 4 antigen -- Ig Distrib in Lymphatic organs -- Cortex Require antigen with MHC -- Sometimes Product of antigenic stim -- Plasma cells and memory cells Fcxn: Antibodies, to INactivate, neutralize, target antigens |
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Table 15.1 -- Properties of T cells
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Site of grwth: Thymus
Antigen surface markers: T-cell receptor. Several CD molecules Circulation in Blood: High numbers Receptors for Antigen: T-cell receptr Distn in lymphatic organ: Paracortical sites (follicle interior) Require Antigen w/ MHC: YES Product of antigenic stim: Several types of sensitized T cells & mem cells Fcxns: Cells fxcn in regulating immune fcxns, killing "foreign" cells; hypersensitivity; synthesize cytokines |
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The basis for most immune responses is the encounter between ?
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Antigens and WBCs
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There are many different classes of T-cell receptors or markers called ?
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CD cluster (cluster of differentiation).
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All CD receptors are capable of recognizing antigen only when it is presented together with ??
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MHC molecules
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CD4 receptors are for?
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T helper cells
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CD8 receptors are for ?
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T cytotoxic cells
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T-cell dependent antigens must be processed by phagocytes called?
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APC
Antigen presenting cells |
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APCs do what? Then what happens to the Ag?
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APCs modify the antigen;
then the Ag is moved to the APC surface and bound to MHC receptor |
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Antigen presentation involves a direct collaboration among what?
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an APC and a T helper cell
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Interleukin-1 is secreted by what to activate what?
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Interleukin-1 is secreted by APC to activate T-helper cells
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Interleukin-2 is produced by what to activate what ?
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Interleukin-2 is produced by T-helper to activate B and other T cells.
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APCs secrete what to activate what?
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Interleukin-1 to activate T-helper cells
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T-helper cells secrete what to activate what?
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Interleukin-2 to activate B and other T cells
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B-cell activation and antibody production (2 things)
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1 - Once B cells process the Ag, interact with Th cells, and are stimulated by growth and differentiation factors, they enter the cell cycle in preparation for mitosis and clonal expansion
2 - Divisions give rise to plasma cells that secrete antibodies and memory cells that can react to the same antigen later. |
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Memory cells are ?
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- Cloned cells bearing specificity
- Persistent, long-term cells that can react with the same antigen on future exposures |
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Antibody structure and Functions
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1. Immunoglobulins
2. Large Y-shaped protein 3. Consist of 4 polypeptide chains 4. Contains 2 identical fragments (Fab) with ends that bind to specific antigen 5. Fe binds to various cells and molecules of the immune system |
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Antibody-Antigen Interactions: (Principle activity)
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Principle antibody activity - unite with the Ag, neutralize the Ag
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Antigen-Antibody interactions
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Opsonization
Agglutination Neutralization |
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Opsonization is ?
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Process of coating microorganisms or other particles with specific antibodies so they are more readily recognized by phagocytes
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Agglutination ?
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Ab aggregation; cross-linking cells or particles into large clumps
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Neutralization is ?
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Abs fill the surface receptors on a virus or the active site on a microbial enzyme to prevent it from attaching
- Antitoxins are a special type of Ab that neutralize bacterial exotoxins |
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What is the principle antibody activity?
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Unite with the Ag, neutralize the Ag
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Classes of Immunoglobulins (5)
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1. IgG
2. IgA 3. IgM 4. IgD 5. IgE |
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IgG
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Monomer, produced by plasma cells (primary response) and memory cells (secondary), most prevalent
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IgA
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- Monomer circulates in blood, dimer in mucous and serous secretions
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IgM
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- Five monomers, first class synthesized following Ag encounter
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IgD
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- Monomer, serves as a receptor for antigen on B cells
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IgE
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Involved in allergic responses and parasitic worm infections
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Which Ig is involved in allergic responses and parasitic worm infections?
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IgE
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Which Ig is produced by plasma cells (primary response) and memory cells and is most prevalent? (and serves in long-term immunity)
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IgG
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Which Ig is produced at first response to antigen and can serve as B-cell receptor?
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IgM
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Which Ig is a receptor on B cells ?
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IgD
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Antibodies: Responses?
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Primary response
Secondary response |
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Primary response
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After first exposure to an Ag immune system produces IgM and a gradual increase in Ab titer (concentration of antibodies) with the production of IgG
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Secondary response
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After second contact with the same Ag, immune system produces a more rapid, stronger response due to memory cells
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Early in the primary response, most of the antibodies are what type?
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IgM
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When the immune system is exposed again to the same immunogen within weeks, months, or even years, what happens in the secondary response?
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The rate of antibody synthesis, the peak titer, and the length of antibody persistence are greatly increased over the primary response.
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Which response to antigens is quick and potent strike against subsequent exposures to infectious agents?
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Secondary response
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B cell and antibodies
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- After B cells activation; Cells differentiate into memory and plasma cells; the plasma cells synthesize and release antibodies (IgM).
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T-Cells & Cell-Mediated Immunity
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- Cell-mediated immunity requires the direct involvement of T-lymphocytes
- T cells act directly against Ag and foreign cells when presented in association with an MHC carrier - T cells secrete cytokines that act on other cells - Sensitized T cells proliferate into long-lasting memory T cells |
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Difference between betwn B cell and T cell response?
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T cell response is cell-mediated immunities.
- Whole T cell acts directly in contact with the antigen. - Stimulate other T cells, B cells, and phagocytes. |
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Types of T cells
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- T helper cells
- Cytotoxic T cells - Natural killer cells |
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T helper cells
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- CD4 or Th
- Most prevalent type of T cell - regulate immune reaction to antigens, including other T and B cells - Involved in activating macrophages and increasing phagocytosis - Differentiate into T helper 1 cells or T helper 2 cells |
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Cytotoxic T cells (CD8 or Tc)
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Destroys foreign or abnormal cells by secreting performs that lyse cells
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Natural killer cells
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Lack specificity
Circulate through the spleen, blood, and lungs |
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T cells & Superantigens
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- Reaction has drastic consequences
- Superantigens are a form of a virulence factor - Provoke overwhelming immune responses by large numbers of T cells - Release of cytokines - Blood vessel damage - Toxic shock - Multiorgan damage |
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Passive immunization is a type of ??
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A type of immunotherapy.
A person is given antibodies. |
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Vaccination: Artificial active immunity?
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Deliberately exposing a person to material that is antigenic but not pathogenic
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What's the principle behind artificial active immunity?
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To stimulate a primary and secondary anamnestic response to prepare the immune system for future exposure to a virulent pathogen.
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Most vaccines are prepared from ...?
(4 things) |
1. Killed whole cells or inactivated viruses
2. Live, attenuated cells or viruses 3. Antigenic molecules derived from bacterial cells or viruses 4. Genetically engineered microbes or microbial agents |
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Table 15.3 Characteristic of Subsets of T cells -- T helper cell 1 (Th1)
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CD4 receptor
- Activates the cell-mediated immunity pathway, secretes tumor necrosis factor and interferon gamma, also responsible for delayed hypersensitivity (allergy occurring several hours or days after contact) |
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Table 15.3 Characteristic of Subsets of T cells -- T helper cell 2 (Th2)
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CD4 receptor.
Drives B-cell proliferation. Secretes IL-4, IL-5, IL-6, IL-10; Can dampen Th1 activity |
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Table 15.3 Characteristic of Subsets of T cells -- T cytotoxic (Tc)
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CD8 receptor.
- Destroys a target foreign cell by lysis; important in destruction of complex microbes, cancer cells, virus-infected cells; graft injection; requires MHC 1 for function. |
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Killed or Inactivate vaccines (2)
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- Cultivate the desired strain, treat it with formalin or some other agent that kills the agent but does not destroy its antigenicity
- Often require a larger dose and more boosters to be effective |
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Live Attenuated Cells or Viruses
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Process that substantially lessens or negates the virulence of viruses or bacteria -- eliminates virulence factors
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Live Attenuated cells or Viruses (Advantages)
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1. Organisms can multiply and produce infection (but not disease) like the natural organism
2. They confer long-lasting protection 3. Usually require fewer doses and boosters |
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Live Attenuated cells or Viruses (Disadvantages)
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Require special storage, can be transmitted to other people, can conceivably mutate back to virulent strain
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If the exact antigenic determinants that stimulate immunity are known, then.....?
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It is possible to produce a vaccine based on a selected component of a microorganism.
- Called Acellular or subcellular vaccines - For viruses: "subunit vaccines" - Antigen can be taken from cultures, produced by genetic engineering, or synthesized |
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Some antigenic molecule types?
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- Capsules = pneumococcus, meningococcus
- Surface protein = anthrax, hepatitis B - Exotoxins = diptheria, tetanus |
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Which of these characteristics is not a major factor in adaptive or acquired immunity? [specificity, chemotaxis, recognition, memory]
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Chemotaxis
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The primary B-cell receptor is ?
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IgD
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In humans, B cells mature in the _____, and T cells mature in the ____.
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Bone marrow, thymus
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Small, simple molecules are ____ antigens?
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Poor antigens
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Which type of cell actually secretes antibodies? [T cell, macrophage, plasma cell, monocyte]
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Plasma cell
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CD4 cells are ____ cells and CD8 are ___ cells.
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helper; Cytotoxic.
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T helper cells receive antigen from ___ and cytotoxic T cells receive antigen from ____.
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Class 2 MHC; Class 1 MHC
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The cross-linkage of antigens by antibodies is known as ???
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agglutination
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The greatest concentration of antibodies is found in the ____ fraction of the serum.
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Gamma globulin
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T ____ cells assist in the functions of certain B cells and other T cells.
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T helper
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Tc cells are important in controlling ???
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Virus infections
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Vaccination is synonymous with _____ immunity?
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Artificial active
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Which of the following can serve as antigen-presenting cells (APCs)?
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B cells, Macrophages, Dendritic cells
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Describe IgG.
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Monomer.
First antibody made during the 2ndary response. Crosses the placenta. Fixes complement. |
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Describe IgA.
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Found in mucous secretions.
A dimer. |
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Describe IgD.
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A monomer.
Primarily a surface receptor on B cells. |
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Describe IgE.
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A monomer.
Involved in allergic reactions. |
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Describe IgM.
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Has greatest number of Fabs (idk).
First antibody made during the primary purpose. Fixes complement. |
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A living microbe with reduced virulence that is used for vaccination ?
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Attenuated
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A vaccine that contains parts of viruses is called ??
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Subunit
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Widespread immunity that protects the population from the spread of disease is called ?
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Herd immunity
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DNA vaccines contain ____ DNA that stimulates cells to make ____ antigens.
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Microbial. Protein.
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What is the purpose of an adjuvant? (idk)
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To improve the contact between the antigen and lymphocytes.
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What cells work closely with macrophages to provide the elegance and complexity of immune function?
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Lymphocytes
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The four main functional types of T cells include all of but which of the following? [Helper cells, suppressor cells, Cytotoxic cells, Delayed hypersensitivity cells, Plasma cells]
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Plasma cells
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Which is not a function of cell surface receptors of macrophages and lymphocytes?
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Determine the intensity of response to an antigen
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Major histocompatibility complex antigens are found on all human cells with the exception of what type of cells?
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Red blood cells
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Of the MHC genes, which codes for receptors that recognize and react with foreign antigens?
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Class 2 MHC
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What class of MHC receptors is found on the surface of all nucleated cells?
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Class 1 MHC
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What leads to the extreme variations in the expression of specific receptors in lymphocytes?
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Clonal Selection
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What is the process by which lymphocyte clones that develop a specificity for self molecules are eliminated or deleted from the pool of genetic diversity?
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Immune Tolerance
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A lymphocyte recognizes and responds to what component of an antigen?
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Antigenic determinant
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What is an example of a poor immunogen?
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Glycogen
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What is the component found in the human body which can serve as a carrier molecule when bound by haptens?
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Serum proteins
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What is responsible for incompatibilities that can occur during blood transfusions?
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Alloantigens
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What are the first cells that recognize a processed and presented T-dependent antigen?
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T helper cells
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What is the function of interleukin-1 (IL-1)?
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It activates T helper cells that have recognized processed and presented antigen.
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Once a B cell has processed and presented an antigen, what event must occur before it becomes activated?
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The B cell must bind to an activated T helper cell that has receptors for the same antigen.
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In what type of reaction do antibodies fill surface receptors on a virus or the active site on a molecule to prevent it from functioning normally?
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Neutralization
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What is the most prevalent antibody circulating throughout the tissue fluids and blood?
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IgG
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What antibody is a significant component of the mucous and serous secretions of the salivary glands, intestine, nasal membrane, breast, lung, and genitourinary tract?
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Dimeric IgA
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What type of cell is fused with a myeloma cell when producing a hybridoma?
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Plasma cell
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What is the mode of action of T cytotoxic cells?
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They secrete perforins that create pores in the membrane of a target cell.
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What is an example of artificial passive immunity?
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A person who receives immune serum during treatment for hepatitis
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