Ch17 Basic Principles of Adaptive Immunity and Immunization Flashcards
Adaptive Immunity (aquired)
immunity obtained in some matter other than heredity Can be naturally acquired or artificially acquired. Can also be active or passive
Naturally acquired adaptive immunity
immunity that is acquired after having a specific disease. Can also be acquired from antibodies transferred to fetus across the placenta or to an infant in colostrum and breast milk.
Artificially acquired adaptive immunity
immunity that is obtained by receiving an antigen by the injection of vaccine or immune serum that produces immunity
Active Immunity
created when the person’s own immune system activates t cells, or produces antibodies or other defenses against an infectious agent. Can be either naturally or artificially acquired
Naturally acquired active immunity
produced when a person is exposed to an infectious agent
Artificially acquired active immunity
produced when a person is exposed to a vaccine containing live, weakened, or dead organisms or their toxins.
Passive Immunity
created when ready made antibodies are introduced into the body. Passive because the hosts immune system does not make antibodies. Can be either naturally or artificially acquired
Naturally acquired passive immunity
produced when antibodies made by a mother’s immune system are transferred to her offspring
Artificially acquired passive immunity
produced when antibodies made by other hosts are introduced into a new host.
Antigen
a substance the body identifies as foreign and toward which it mounts an immune response
Epitope
also called antigenic determinants; areas on the molecule to which antibodies can bind
Hapten
a small molecule that can act as an antigen if it binds to a larger protein molecule. Also can act as eptiopes on the surfaces of proteins,
Humoral Immunity
carried out by antibodies circulating in the blood. When stimulated by an antigen, B lymphocytes initiate a process that leads to the release of antibodies.
Cell-mediated immunity
carried out by T cells. It occurs at the cellular level, especially in situations where antigens are embedded in cell membranes or are inside host cells and are thus inaccessible to antibodies.
Adaptive Immunity must be able to do the following
(1) recognize self vs non self
(2) specifically react to each antigen that it encounters
(3) have heterogeneity so that every antigen will cause a specific immune response to it
(4) Be able to remember that it has seen the antigen, so if one is exposed to the antigen a second time, the immune response will be faster than the first encounter with the antigen. The quantity of antibody produced during the secondary response will also be greater than during the primary response
Plasma Cells
possesses the specific monomer IgM antibody on its surface that can recognize and bind to antigens. This stimulates the B cell to produce antibodies. The type of b cell that secretes antibodies is known as a plasma cell
Immunoglobulins (Ig)
the basic units of antibodies. Y shaped protein molecules that are composed of four polypeptide chains, two identical light chains and two identical heavy chains. The chains possess constant regions and variable regions
Constant Region
determines the particular class that an immunoglobulin belongs to
Variable region
has a particular shape and charge that enables the molecule to bind a particular antigen
5 classes of antibodies
IgG, IgM, IgA, IgE, IgD
IgG
the antigen binding sights of IgG attach to antigens on microorganisms, and their tissue binding sights attach to receptors on phagocytic cells. Also activates the complement system. The only immunoglobulin that can cross the placenta from mother to fetus
IgA
Guards entrances to the body by binding antigens on microorganisms before they invade tissues. Also activates the complement system
IgM
the first antibody secreted into the blood during the early stages of a primary response. Also activates the complement system and is the first antibody formed in life.
IgE
Has a special affinity for receptors on the plasma membranes of basophils in the blood or mast cells in the tissue. Plays a damaging role in the development of allergies to such agents as drugs, pollens, and certain foods.
IgD
found mainly on B cell membranes and rarely secreted, function is unknown
Primary Humoral Response
Occurs when the antigen is first recognized by host B cells. After recognition, B cells divide to form plasma cells, which begin to synthesize antibodies. The first antibodies are IgM. Next, cytokines cause a switch in class and IgG is produced. Eventually production of the two antibodies wanes, and they become virtually undetectable. However, B cells that have proliferated and formed memory cells persist within the lymphoid tissue.
Secondary Humoral Response
Occurs when an antigen recognized by memory cells enters the blood. The presence of memory cells makes this response much faster than the first. IgM and IgG are produced in the same order. However, IgM is produced in smaller quantities over a shorter period and IgG is produced sooner and in much larger quantities.
T cell independent antigens.
antigens that bind to and activate B cells without the help of Helper T cells.
T cell dependent antigens
Antigens that must activate both a B cell and a Helper T so that they can make contact with eachother. Once the two make contact, the B cell activates the Helper T cell causing it to secrete lymphokines that further activate the B cell causing it to differentiate and proliferate.
Antibody Mechanisms to Destroy foreign agents
neutralization, opsonization, and cell lysis
Neutralization
inactivation of bacterial toxins through the formation of antigen-antibody complexes
Opsonization
found in last set of flash cards
Cell lysis
Antibodies bind to the microbe and break down its plasma membrane, causing it to lyse
Monoclonal antibodies
antibodies produced in the laboratory by a clone of cultured cells that make one specific antibody. One method involves myeloma cells (malignant immune system cells) that are mixed with sensitized lymphocytes. They then fuse together to make a hybridoma, which contains genetic info from both and produces large quantities of antibody.
Helper T Cells
stimulated when they are presented with an antigen (attatched to the MHC II protein) from a macrophage or B cell. Once stimulated, the helper T cells release chemical mediators, like interlukins and lymphokines, which can either help B cells or stimulate macrophages.
Cytotoxic T Cells
stimulated when the antigen is presented (attatched to MHC I protein) from a macrophage. This T cell can now kill infected cells directly by releasing perforins directly into the infected cells.
Natural Killer cells
NK cells do not need to be presented with the antigen from the macrophage to become activated but they also destroy cells by releasing perforins into them
Delayed Hypersensitivity T Cells
once sitmulated by antigen, release a number of lymphokines, which attract macrophages to get to the site of the infection as well as cause an increase in macrophage activity
Immune response to bacterial infection
(Bacterial): certain immune responses alter the invading organisms so that they can be phagocytized. Plasma cells also make specific antibodies that can interfere with a any of several steps in bacterial invasion. They can prevent bacterial attachment to cell surfaces, opsonize bacteria, and neutralize bacterial toxins or inactivate bacterial enzymes.
Immune response to viral infection
Interferons, secretory IgA, and some IgG anitbodies prevent or minimize entry of viruses. IgG and IgM act in the blood to neutralize viruses directly or to promote their destruction through complement. Cytotoxins and cellular immunity via TC cells and NK cells are especially important. Fever also plays a role.
