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50 Cards in this Set
- Front
- Back
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When is adaptive immunity acquired?
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only after an immunizing event (infection, vaccine)
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How B and T lymphocytes play a role in this?
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B and T lymphocytes undergo a process that prepares them for reacting only to one specific antigen/immunogen
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What are antigens or immunogens?
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molecules that stimulate a response by B and T cells
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What are foreign molecules?
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they are microbe products, molecules or cancer cells, transplanted tissue; protein or polysaccharide molecules on or inside cells and viruses
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What is an epitope?
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a portion of an antigenic molecule that the B/T cells bind/ respond to
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What are haptens?
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molecules too small to elicit an immune response on its own
Ex: drugs and metals |
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What are the principle stages of immunologic development and interaction?
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lymphocyte development and differentiation
presentation of antigens challenge of B and T cells by antigens T-lymphocyte response: cell-mediated immunity B-lymphocyte response: production and activities of antibodies |
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What is the overview of the stages of lymphocyte development and function?
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I. development of B and T lymphocyte specificity and migration to lymphoid organs. II. antigen processing by dendritic cell and presentation to lymphocytes; assistance to B cells by T cells. III. lymphocyte activation, clonal expansion and formation of memory B and T cells. IV. end result of lymphocyte activation. Left hand side: antibody release; right hand side: cell mediated immunity.
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What are cell surface markers?
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all cells have a variety of different markers on their surfaces for detection, recognition (helps T cells know foreign vs. self), cell communication
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What is the class I of the Human Major histocompatibility (MHC) complex
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class I MHC molecule is found on all nucleated human cells
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What is the class II of the Human Major histocompatibility (MHC) complex?
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class II MHC is found on macrophages, dendritic cells and B cells (class I is also here of course)
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What happens when B and T cells are challenged by an antigen?
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they both proliferate and differentiate
-clones are made --some are memory cells (do nothing now) --some are effector cells (actually do the work of the immune response) |
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What are the three functional types of T cells?
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helper T cells, regulatory T cells, cytotoxic cells
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What are helper T cells?
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activate macrophages, assist B-cell processes, and help activate cytotoxic T cells
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What are regulatory T cells?
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control the T-cell response
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What are cytotoxic T cells?
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lead to the destruction of infected host cells or "foreign cell"
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How do B cells respond to antigen?
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when activated, B cells divide and give rise to plasma cells and memory cells
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What do plasma cells release?
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antibodies
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What is the site of maturation for B cells?
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bone marrow
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What is the site of maturation for T cells?
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thymus
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What do B and T cells need to be to work?
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immunocompetent (mature); they do not bind to self antigens; they can recognize MHC classes
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What is the B and T cell receptor role?
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the role is to accept or grasp one specific antigen
-b cells have receptors that bind antigens -t cells have receptors that bind processed antigens |
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What is the origin of immunologic diversity generated by?
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diversity is generated by rearrangement of gene segments that code for antigen receptors on T and B cells
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What is the mechanism behind antibody variability?
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gene encoding variable regions (top part of protein-bottom part is constant (Y))--different RNA transcripts from same gene--different amino acid sequences in finished protein
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How are antigens presented?
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In most immune reactions, the antigen must be further acted upon and formally presented to lymphocytes by antigen presenting cells (APCs)
Ex: B cells, macrophages, dendritic cells (all presenting antigens in MHC II |
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How is an antigen presented to T cells?
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1. MHCII antigen on the APC binds to T cell receptor
2. Coreceptor on Tcell hooks to MHCII receptor, then activates T helper cells, secretes IL-1, T helper cell produced IL2; this then helps activate Bcells 3. antigen present cells (APCs) engulf a microbe and degrade it into pieces; antigens are then presented to a T helper cell which is specific for the antigen being presented |
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What is a clone?
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each genetically unique line of lymphocytes arising from extensive recombinations of surface proteins
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What is immune tolerance?
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any lymphocytes that develop a specificity for self molecules and could be harmful are eliminated from the pool of cells
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How is clonal selection and expansion of B and T cells done?
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-the specificity for a single antigen molecule is programmed into the lymphocyte and is set for the life of the given cell
-when any antigen enters the immune surveillance system, it encounters specific lymphocytes ready to recognize it - stimulates mitotic divisions and expands into a larger division on lymphocytes all bearing the same specificity |
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What are T helper cells (Th)?
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they regulate immune reactions to antigens
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What to Th secrete?
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they secrete interleukins to stimulate T cells (cytotoxic) and B cells
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What are Th cells also involved in?
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also involved in activating macrophages
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What are cytotoxic T cells (Tc)?
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cells that kill other cells
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What are virally infected cells?
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they recognize virus peptides displayed on the cell surface (in MHC I)
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What are cancer cells?
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Tc constantly survey the tissues and immediately attack any abnormal cells they encounter
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What are cells from other animals and humans used for?
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-the most important factor in graft rejection : T cells attack foreign tissues that have been implanted into a recipient's body
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What are the steps of T cell activation?
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PG 360
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What are the steps of B cell activation?
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PG 362
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What does the working model of antibody structure look like?
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Y
top part of Y has antigen binding sites in the bottom part of Y it has two disulfide bonds bottom part of stem of Y has binding sites for cells |
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What is lgG?
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80% Abs (antigen binding sites) in blood protect against bacteria, viruses; enhance phagocytosis; neutralize toxins; trigger complement; can cross placenta
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What is the summary of antibody functions?
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PG 363
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What is immunological memory?
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1000s of memory cells exist after initial encounter with an antigen
next time antigen appears it can proliferate and differentiate within hours, faster and more intense -primary response: rise in IgM then IgG -secondary response: Abs made faster PG 365 |
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What are the two branches of humoral immunity?
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active immunity and passive immunity
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What are the two branches of active immunity?
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naturally acquired: infection-contact with pathogen
artificially acquired: vaccine- dead or attenuated (weakened) pathogens |
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What are the two branches of passive immunity?
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naturally acquired: antibodies pass from mother to fetus via placenta or to infant in milk
artificially acquired: injection of immune serum (gamma globulin) |
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What is an artificial active immunity?
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vaccines
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What are the basic principals behind vaccination?
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stimulate a primary response and a memory response
-if the pathogen enters the body, the response will be immediate, powerful and sustained |
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What are the principal of vaccine preparation?
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-whole cell or virus vaccines: live, attenuated cells or viruses; killed cells or inactivated viruses
-antigenic molecules: derived from bacterial cells or viruses (subunits) |
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Development of new vaccines
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vaccines for HIV/AIDS malaria, worm infections have not been found
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How are new vaccines prepared?
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1. DNA that codes for protein antigen is extracted from pathogen genome
2. genomic DNA is inserted into plasmid vector and prepared as vaccine 3. DNA vaccine is injected into subject 4. cells of subject accept plasmid; DNA is transcribed and translated into various proteins 5. Foreign protein of pathogen is inserted into cell membrane where a response will be stimulated |
