Terms in this set (25)
targets specific antigens
immune system differentiates b/w self and nonself cell using the MHC
depends on body's ability to recognize specific antigens one at a time
required innate immunity
adaptive immunity, develops only in vertebrates, following exposure to agents such as microbes, toxins, or other foreign substances
involves both a humoral immune response and a cell-mediated immune response to a specific antigen in the body.
MHS major histocombatibility complex
distinguishes between self cells (healthy and non healthy)
Tissues are immunogically "typed" before an organ transplant to make sure that the donor and recipient match as closely as possible in their MHC
cell mediated response
infections that have made way into cells
controlled by T cells
Cell-mediated immune response involves activation of T cells, production of cytotoxic T cells and helper T cells, and the release of interleukins
¤ Interleukins initiate positive feedback that results in the production of more interleukins and lymphocytes
Helper T cells are part of this
Cell-mediated immunity differs from humoral immunity in that respond differently to invaders
CYTOTOXIC T CELLS
BOTH: HELPER T CELLS, CYTOKINES, MEMORY CELLS, ANTIGEN-PRESENTING CELLS
for infections in blood/lymph
controlled by B cells
Humoral immune response involves activation B cells, production of plasma and memory cells, and the stimulation of further B cell production by helper T cells
Antibodies are part of the "humoral" immune responses. Circulating antibodies encounter microorganisms in body fluids and complex with them to "mark" them for further counterattack.
ANTIBODIES, PLASMA CELLS, B CELLS
BOTH: HELPER T CELLS, CYTOKINES, MEMORY CELLS, ANTIGEN-PRESENTING CELLS
T cells & B cells - made in bone marrow, T cells mature in thymus
Natural killer cells - not phagocytic
recognize and respond to antigens, foreign molecules
Lymphocytes that mature in the thymus above the heart are called T cells, and those that mature in bone marrow are called B cells
is a foreign molecule that evokes a specific response by a lymphocyte
Antigen receptors embedded in their plasma membranes enable specific B cells and T cells to recognize and bind to a specific antigen or antigen fragment. After encountering an antigen or antigen fragment it recognizes, the lymphocyte becomes activated, triggering a response called clonal selection (sometimes called clonal expansion). Clonal selection produces effector cells and memory cells of the activated lymphocyte.
antibodies bind to antigens
attract macrophages to eat bacterium
complement proteins drill hole in bacterial membrane - explodes cell by letting water rush in
contains a lot of antibodies on the surface
when it finds a matching antigen it splits to daughter cells and clones itself
body assumes there are many viruses so it prepares to destroy virus (takes one week)
plasma cells released into the body to find antigens, specific antibodies then circulate
plasma membranes contain special antigen receptors that act like antibodies
¤ Antibodies are Y-shaped proteins unique to particular antigens
¤ They inactivate antigens by binding to them
¤ Antibodies are sometimes called immunoglobulins (Ig)
When B cells encounter antigens that bind to their antibodies, they produce two types of daughter B cells
¤ Plasma cells release their specific antibodies, which then circulate in the body
¤ Memory cells do not release their antibodies, instead circulate in the body to respond quickly to a subsequent invasion by the same antigen
Clonal selection is the division of B cells that have been stimulated by binding to an antigen, which results in the production of cloned plasma/memory cells.
dont release antibodies instead of circulation to respond to an invasion
ex. chicken pox, vaccines
do not release their antibodies, instead circulate in the body to respond quickly to a subsequent invasion by the same antigen
is responsible for the rapidity of the secondary immune response
aid in infections in cells
recognizes antigens and use MHC to do that
starts to divide once they recognize antigen
use perforin to drill in cell membrane and lysis
T cells' plasma membranes have antigen receptors for molecules displayed by nonself cells; nonself is determined by...
¤ Absence of known MCH
¤ Additional markers present
on infected self cells
¤ Cancer or transplanted cells displaying aberrant markers
When T cells encounter nonself cells, they produce two types of daughter cells
¤ Cytotoxic/killer T cells cause nonself cells to lyse
¤ Helper T cells stimulate the production of B cells and cytotoxic T cells
helper T cells
stimulate B cell production that mask an antigen and more cytotoxic T cells
interact with the antigen-class II MHC complex presented by macrophages.
Specific helper T cells recognize specific antigen-class II MHC complexes. The result of this is an activated helper T cell that stimulates both humoral and cell-mediated immune responses.
T cell receptor, recognizes antigen
recognized the MHC
signaling molecule between leukocytes
rips off antigens for innate immunity for info for acquired immunity - use this to launch cells for innate
cytotoxic T cells
CD8 recognizes MHC
attack body cells that have been infected
Nonspecific defense includes natural killer cells that destroy virus-infected body cells, and abnormal cells that could form tumors. Cytotoxic (killer) T lymphocytes kill cancer cells and cells infected by viruses or other intracellular pathogens.
The role of cytotoxic T cells is the secretion of perforin, which plays a role in the cell mediated immune response.
A cytotoxic T cell is activated through interaction with antigen-presenting cells and signals from helper T cells. Once a cytotoxic T cell has been activated, it can recognize an infected cell presenting a specific antigen fragment on its surface. The T cell receptor (TCR) recognizes the class I MHC-antigen fragment complex, and the CD8 protein on the cytotoxic T cell binds to the MHC molecule.
To kill the infected cell, the cytotoxic T cell secretes perforin and granzymes. Perforin perforates the cell by forming pores, allowing granzymes to enter the cell and break down proteins. This leads to apoptosis, or programmed cell death. Once a cytotoxic T cell has induced apoptosis in a cell, it moves on to attack other infected cells or cancer cells.
ready made antibodies
natural when antibodies pass body not exposed in any way ex. mother to fetus
acquired because your cells generate antibodies
phagocytic leukocyte that can engulf a foreign bacterium
B cells that have been stimulated by interleukin-2 develop into plasma cells
produce and secrete antibodies
Extracellular pathogens such as viruses and bacteria in body fluids are attacked by antibodies from plasma cells
Plasma cells are the effector cells of the humoral response; they secrete antibodies that neutralize or tag the foreign pathogen for destruction
A primary reason for needing a new vaccine for influenza each year is that mutation in the influenza virus is frequent
The virus that causes one year's flu outbreak has a high rate of mutation, resulting in antigenic variation that the immune system cannot recognize.
When a B cell encounters an antigen it recognizes via its antigen receptors, it internalizes part of that antigen and presents a fragment of the antigen with a class II MHC molecule. An activated helper T cell (activated after an encounter with an antigen-presenting cell) can then recognize this class II MHC-antigen fragment complex on the surface of the B cell and bind to it. This interaction, along with cytokines the helper T cell releases, activates the B cell. The B cell then proliferates and differentiates into plasma cells and memory cells. Plasma cells secrete antibodies that neutralize the pathogen or mark it for destruction. Memory B cells aid in the secondary immune response, should the body encounter the same pathogen again.
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