Immune System II Flashcards
_____ are immunocompetent (mature) lymphocytes created during an infection. They
remain alive long after the infection, allowing the body to “remember” the antigen and
react quickly if it returns.
Memory cells
Memory cells express _____ that was expressed by the parent lymphocyte.
the same antigen receptor
For the body to mount a specific defense against a newly encountered invader takes
_____ . (There may be only a single lymphocyte in the body that happens to
bind to it!)
days or weeks
The response to a newly encountered invader is called the _____.
primary immune response
Re-exposure, even years later, to an antigen that has been responded to before results in
a specific defense that takes _____ to mount. This is due to the presence of _____.
(There are thus many lymphocytes in the body that are able to bind to the antigen.)
only hours; memory cells
The response to an invader that has been attacked in the past is called the _____.
secondary immune response
Once a lymphocyte is capable of binding to a specific antigen, it is said to be _____ or
_____.
mature; immunocompetent
Immunocompetent lymphocytes have a set of _____ on their surface which can bind to a
specific antigen.
receptors
The antigen binding receptors of lymphocytes are produced by the _____ that produce
them, so that the number that can be made by a single person is very large.
shuffling of portions of the
genes
. Immature lymphocytes are formed from hematopoietic stem cells in the _____.
bone marrow
Each immature lymphocyte displays _____, but most such cells are unwanted.
a single antigen-binding
receptor
Lymphocytes whose antigen receptors do NOT react with ‘self’ cells are said to be _____,
but many immature lymphocytes do not meet this standard.
tolerant
Most B-cells whose receptors bind to “self” proteins are destroyed in _____.
the bone marrow
In the thymic cortex, immature T-cells that _____ are allowed to survive until the next
stage: those that can’t, die. (+ binding = live) This is called _____ selection.
recognize “self” MHC proteins;
positive
In the thymic medulla, immature T-cells whose antigenic receptor binds to _____ are killed
(- binding = live). This is called _____ selection.
“self” proteins displayed by the
MHC; negative
The acquired immune response can be divided into two branches: the _____ response
recognizes antigens or pathogens that are not associated with any “self” cells.
humoral
The acquired immune response can be divided into two branches: the _____ response
recognizes antigens that are associated with “self” cells (such as virally infected cells, or
antigen presenting cells).
cell-mediated
Humoral immunity is mediated by _____ produced by plasma cells present in the body’s
“humors” or fluids.
antibodies
B-cells recognize antigens that are _____: that is, that are not displayed as part of a MHC
free in the body
The first response in the humoral branch of the immune response is _____.
the binding of a B-cell to an
antigen
When a B-cell encounters an antigen and has been activated, it proliferates into two types
of cells: _____ and _____.
plasma cells; memory cells
Plasma cells produce antibodies that can bind to _____.
the same antigen that was
recognized by the parent B cell
Antibodies are produced by _____ in the lymph.
plasma cells
Antibodies are _____, each of which can bind to _____ identical antigens.
proteins; two or more
Most antibodies are essentially Y-shaped: the stem of the Y is _____ and the branches of
the Y are _____ and are called the _____.
constant; variable; variable
region
It is the differences in the _____ that enables different antibodies to bind to different
antigens.
variable region
\_\_\_\_\_ refers to the fact that antibodies “get in the way,” so to speak, interfering with the function of the proteins or cells to which they bind.
Neutralization
_____ refers to the fact that, since each antibody can bind to two antigen molecules, they
can cause the antigen (or cells which display it) to clump. This makes them vulnerable to
_____.
Agglutination; the non-specific
immune system
Elements of the non-specific immune system, including macrophages and complement
proteins, recognize antibodies in the body which _____. This results in the destruction of
the antigen.
have bound to an antigen
Although Y shaped, compared to fibrous proteins, antibodies are round or globe shaped.
Thus, antibodies are called the _____.
immunoglobulins (Ig)
Antibodies are divided into five classes based on their structure: _____, _____, _____,
_____ and _____.
IgA; IgD; IgE; IgG; IgM
Most _____ is found as a dimer (two stuck together) in body secretions, and helps to
_____.
IgA; prevent pathogens from
attaching to the body’s surface
_____ serves as an antigen receptor for B-cells: it is physically attached to their surface.
IgD
_____ is found in barrier regions, bound to mast cells and basophils: antigen binding
causes the cells to _____.
IgE; release histamine and
other inflammatory chemicals
Most antibodies are _____. When bound to an antigen, these are recognized by other
components of the immune system, which then _____.
IgG; destroy the object to which
it is bound
The monomer form of _____, like IgD, serves as an antigen receptor for B-cells.
IgM
As a pentamer (five units bound together), _____ is the first antibody released by new
plasma cells and so can serve as a marker for an active infection.
IgM
Like IgG, when bound to an antigen, the pentameric form of _____ is recognized by other
components of the immune system which destroy the object to which it is bound.
IgM
_____ is mediated by T lymphocytes which respond only to living cells which display both
_____ and _____.
Cell mediated immunity; foreign
antigens; “self” (MHC) proteins
When T-cells bind to a non-self cell and are activated, they proliferate, leading to the
production of _____, _____, _____ and _____ T cells.
killer; helper; suppressor;
memor
Killer T-cells are also called _____ cells or _____ cells.
cytotoxic T; CD8
Killer T-cells recognize MHCI proteins mixed with antigens, and respond by _____.
producing toxins which cause
the infected cells to die
Helper T-cells are also called _____ cells, because of the major receptor they express on
their surface.
CD4
The function of helper T-cells is to stimulate B-cells to _____, and to stimulate both B-cells
and T-cells to _____. (That is, they produce co-stimulators.)
produce antibodies; divide
. Without _____ there can be no adaptive immune response.
helper T-cells
An interleukin is a type of cytokine which is released by \_\_\_\_\_ and allows communication between leukocytes (inter-leukocyte communication). Interleukin is a co-stimulator and activates \_\_\_\_\_.
helper T-cells and APCs;
antigen-bound lymphocytes
_____ are needed at the end of an infection to shut down the immune response.
Suppressor T-cells
_____ are the most similar to the parent T-cell: they remain in circulation long after the
infection is over, ready to recognize the pathogen if it returns.
Memory T-cells
One way that we medically supplement the immune response is to directly kill the
pathogen (if it is bacterial or eukaryotic) by the use of _____.
antibiotics
One way that we medically supplement the immune response is to inject _____ that are
_____ the pathogen, so that the body will recognize it in the future. (This is called
vaccination.)
harmless antigens; derived in
some way from
One way that we medically supplement the immune response is to directly transfer
antibodies from one individual to another: this confers _____.
passive immunity
The immunity created by our own immune system is called _____.
active immunity
Newborn infants have passive immunity to many pathogens due to _____.
transfer of maternal antibodies
through the placenta
Transplant success depends on the similarity of the tissues because cytotoxic T-cells, NK
cells, and antibodies work to _____.
destroy non-self tissues
Autografts are tissue grafts transplanted from _____.
one body site to another in the
same person
Allografts are grafts transplanted from _____. Currently, to be successful, the immune
system must be suppressed.
individuals that are not
genetically identical but belong
to the same species
Xenografts are grafts _____. Currently, to be successful, the immune system must be
suppressed.
taken from another animal
species
_____ are any congenital or acquired conditions that cause immune cells, phagocytes, or
complement to behave abnormally.
Immunodeficiencies
Severe combined immunodeficiency (SCID) is a congenital condition that produces a
deficit of _____.
lymphocytes
Acquired immune deficiency syndrome (AIDS) cripples the immune system by interfering
with _____.
helper T-cells
_____ occur when the immune system loses its ability to differentiate between self and
non-self. As a result, the body _____.
Autoimmune diseases; attacks
its own cells
Hypersensitivities, or allergies, are the result of the immune system causing tissue
damage as it attacks _____.
a harmless substance
