Adaptive Immunity Flashcards
What are some key differences between active and passive immunity? Please give examples.
Self created vs non self created
strength of immunity
Define an antigen.
Usually a foriegn substance that activates immune response. Usually made of proteins, and are parts of a virus, bacteria, or helminth.
Describe the process by which B-lymphocytes are activated if the antigen is T-independent.
B cell binds to t-independent at multiple spots and is activated directly and proliferates into mem B and plasma.
Define epitope and hapten.
hapten: a small antigen that must bind to a carrier molecule to bind to an antibody. Allergens.
epitope- antigenic determinant, portion of antigen that is binding to the antibody.
Which type of cytokine is a key co-stimulator of T cell activation?
interleukins
Describe the process that results in an antigen-presenting cell. Which cells can act as APC’s?
Cells are dendritic, macrophages, and activated B cells.
antibody titer
measurement of the amount of antibodies present after exposure to an antigen
Describe the 5 classes of antibodies (MADGE). For each describe its structure, function and relative percentage in the blood (most to least).
Most to least
IgG- crosses placenta, immune response
IgA- in secretions
IgM- first to be secreted by plasma cells
IgE- allergic response and attached to basophils
IgD- unknow use, possibly receptor
What does it mean for a B or T cell to immunocompetent? What do they acquire?
They have their unique receptors.
Distinguish between exogenous and endogenous antigen as well as autoantigens.
Exogenous-outside of host cell
Endogenous- inside host cell (virus)
autoantigen- not foreign normal self tags on cells.
How do activated cytotoxic T cells kill their targets?
perforin-granzyme cytotoxic pathway- perforins poke holes in cells and granzymes destroy them with enzymes
CD95 cytotoxic pathway- CD95 glycoprotein present on most cells and binds to CD95L receptor on Tc cells. Activates enzymes that cause cell death
helper T cells
Director of the immune response and stimulate cytotoxic t cells and b cells.
opsonization
coating a microbe with antibodies to enhance phagocytosis
neutralization
cages off antigen and prevents from damaging cells
memory T cells
clones of the original Th cell that remember an antigen and create a stronger and longer immune response the second time
How does the production of antibody in response to a secondary exposure to an antigen compare to the primary response?
Secondary response happens faster, with more antibodies, and lasts a longer time.
Describe how T cells achieve self-tolerance and where
Happens in thymus
Positive selection: cells that recognize MHC are kept
Negative selection: cells that do not recognize autoantigens are kept
How are T-dependent and T-independent antigens different? Which cells can be activated by T-independent antigens?
T-dependent antigens require a Th cell response to activate Tc and B cells.
T-independent antigens can activate B cells independently.
Which cells play a role in adaptive immunity?
B+T lymphocytes
Briefly describe the structures of the lymphatic system. Which structures are primary structures and which are secondary structures.
Primary: Red bone marrow and thymus
Secondary: lymph nodes, MALT, spleen
How is it that we develop a memory for an antigen? What cells and cell products provide this memory?
Memory T and B cells
Describe some characteristics of adaptive immunity.
specificity, clonality, self-tolerance, and memory
Distinguish between MHC-I and MHC-II.
MHC 1- on all nucleated cells
MHC 2- only on antigen-presenting cells
List and describe the four ways in which immunity is acquired.
artificially acquired active immunity- vaccine
artificially acquired passive immunity- immunotherapy
naturally acquired active immunity- got sick
naturally acquired passive immunity- mother-child
Distinguish between exogenous and endogenous antigen processing.
Exogenous- take in antigen from outside the cell and process. Cells phagocytize antigen, digest anitgen with lysosome, vesicles with MHC 2 merge with phagolysosome and epitopes bind to MHC 2 receptors, MHC 2 vesicle merges with cell membrane to present epitope.
Endogenous- processed antigen binds to MHC 1 receptor on endoplasmic reticulum. MHC-1 and epitope complex is packaged in golgi body before displaying on the plasma membrane.
cytotoxic T cells
directly kill infected or cancerous cells
Describe how B cells achieve self-tolerance (aka clonal deletion of B cells.)
B cells that bind with autoantigens are lysed.
antibody-dependent cellular cytotoxicity
Similar to opsonization, the coating of antibodies attracts NK cells that destroy the cell. Often happens on worms.
Describe the function of the major histocompatibility complex.
To present epitopes to B and T lymphocytes.
Describe the general structure of antibodies. What are antibodies made of?
Antibodies are made of proteins. Contain two heavy chains of amino acids and two light chains, jointed by disulfide bonds at the hinge.
Constant region- the same as all other antibodies in it’s class
Variable region- antigen-specific
suppressor T cells
a special type of Th or Tc cell, that has an inhibitory factor that turns off an immune response.
Distinguish between the roles that B and T cells play in the adaptive immune response.
T related to cell-mediated immunity
B related to humoral immunity
Give an overview of the humoral immune response.
antibody-mediated immunity
B cells differentiate into plasma cells and memory B cells
Plasma cells secrete antibodies
Describe the process by which B-lymphocytes are activated if the antigen is T-dependent.
Th cell is activated after receiving epitope from APC
Th cell changes to a Th2 through interleukin
B cells that have the appropriate MHC-II epitope complex will bind to Th2 cell.
Interleukin and binding activates B cell and causes proliferation
agglutination
clumping of cells to increase phagocytosis and prevent invaders from sticking to cells
Describe how cytotoxic T cells are activated. Which cells play a role in assisting with the activation?
Assisted by Th cell
APC presents processed antigen to on MHC1 and binds to Tc cell.
Th cell binds to MHC2 on APC and secretes interleukins which transforms it to Th1.
Th1 secretes interleukin which activate Tc cell.
Tc cells become self stimulatory and proliferate.
