Test #1-Immunology Flashcards
what is non-specific/innate immunity?
pre-existing defenses providing rapid, local response to an invador
what is specific/adaptive immunity?
response to a specific immune stimulus that involves cells of the immune system and frequently leads to a state of immune memory
Which immunity type is antigen-independent?
non-specific/innate
which immunity type is has an immediate maximal response?
non-specific/innate
which immunity is antigen-dependent?
specific/adaptive
which immunity has a lag time between exposure and maximal response?
specific/adaptive
which immunity results in immunologic memory?
specific/adaptive
What are the granulocytes?
neutrophils, basophils, eosinophils, monocytes (which give way to macrophages and dendritic cells)
natural killer cells are a part of which immune system?
innate immune system, as they do not need contact with antigen
How do natural killer cells work?
they are cytotoxic, they attack cells that have been infected by microbes but do not attack the microbes themselves
what are the primary functions of a macrophage?
phagocytosis and antigen presentation
T lymphocytes
differentiate in the thymus, are long lived, are many types: t helper cells which coordinate immune system, t cytotoxic cells which are responsible for destroying infected cells, and t regulatory cells which suppress immune response and modulate immune system function
B lymphocytes
differentiate in the fetal liver and switch to the bone marrow, differentiate into plasma cells which are responsible for antibody production, and memory b cells which are formed specific to antigens encountered during the primary immune response and are able to live for a long time to respond quicker upon second exposure to the same antigen
types of cytokines
lyphokines, interleukins, tumor necrosis factor, interferons, transforming growth factor
peripheral lymphoid organs
sites where lymphocytes are gathered to contact antigens
lymph nodes, spleen, appendix, tonsils, and adenoids
primary lymphoid organs
where hematopoietic stem cells that will become T and B cells mature
lymphatic vessels
flow within lymphoid system occurs via vessels that carry lymp which is collected from the fluid that bathes the body’s tissues
Thymus
responsible for immunogenesis in children, location of maturation of T lymphocytes produced in bone marrow, produces thymosin, thymus is not exposed to antigen
size and activity of thymus as we age
starts out big and gets bigger until puberty then gets smaller (biggest at puberty), but function is highest in childhood
What are the two types of CD4 T cells
TH-1 induce cell mediated immune response
TH-2 activate B cells to produce antibody
What are CD8 T cells?
cytotoxic cells, destroy virus infected cells and tumor cells, they find and destroy
characteristics of positively selected T cells
foreign antigen specific
not autoreactive
what happens to negatively selected T cells
apoptosis because they are not functional
what type of immunity and what is the function of the mucous membranes?
non-specific
the intestinal tract produces various enzymes and acid
the urine flushes microbes from urinary tract
cilia lining surfaces beat constantly upward to to propel microbes to throat to be swallowed
provides a mechanical barrier
What are the antimicrobial substances and their function of innate immunity?
sweat-creates dry salty surface of the skin
lysozyme-found in tears, saliva and mucous, degrades peptidoglycan
peroxidase-breaks down hydrogen peroxide
what is the function of toll-like receptors?
found on a variety of host cell types
recognize compounds unique the microbes, allows cells to send chemical messages called cytokines to other systems
what is the function of complements?
series of proteins always present in blood that act in conjunction with adaptive immune defenses, can become activated leading to a chain of events that results in microbe destruction
what are the two phagocytes?
macrophages: always present in tissue can be recruited to site of injury activated macrophages have greater killing power
neutrophils: more killing power than naive macrophages rapidly recruited to site of injury
what is the inflammation response generated by innate immunity?
injury/invasion:cells sense and communicate trauma via cytokines, complement proteins also assist in sensing invasion
dilation of blood vessels: dilation of vessels allows fluid and cells to exit bloodstream and enter area of damage
fever: possible outcome of inflammation, induced by cytokines and sometimes by bacterial endotoxin
How does the specificity of the adaptive immunity work?
recognition of foreign substances, a small molecule called a hapten can also act as an antigen but only when bound to a larger molecule
What is the humoral response of adaptive immunity?
eliminates antigens that are extracellular for example bacteria in the bloodstream
B cells produce this antibody
what is the cell-mediated response of adaptive immunity?
deals with antigens residing in within a host cell, for example a virus infected cell
T cells carry the burden for this job
what is the structure of antigens?
large carrier molecule with epitopes (antigenic determinatnts) projecting from surface
epitopes interact with antibody and T cells
What are the origins of antigens?
exogenous-those that have entered the body from the outside (inhalation, ingestion, injection)
endogenous-those that have been generated within the cell as a result of normal cell metabolism or because of viral or intracellular bacterial infection
superantigens
do not behave as normal antigens, rather than attaching to the MHC groove and triggering the normal immune response, superantigens attach onto the sides of the binding site
as a result T-cells go on an unregulated rampage uncontrollably releasing regulatory molecules such as interferons in toxic amounts
Structure of class I MHC and class II MHC
6 genes for MHC I
1 gene for MHCII called HLA-D
HLA genes found on chromosome 6
the gene products of HLA genes are membrane associated molecules generically referred to as MHC I and MHC II
Which cell does Class I MHC molecules present to?
cytotoxic T cells
Class I MHC
found on all nucleated cells, display ordinary surface proteins, also presents “abnormal” proteins on surface of virus infected cells or tumor cells for inspection by cytotoxic T cells, cytotoxic T cells will ignore normal “self” proteins but will destroy cells presenting “non-self” proteins
some viruses and tumors can block MHC I
How do Class II MHC present?
present antigens from outside cell
display “non-self” which will be recognized by helper T cells
MHC II proteins are found only on immune cells called antigen presenting cells
Which is a more powerful killer activated dendritic cells or activated macrophages?
activated macrophages-have more lysosomes and more digestive enzymes
Where are activated dendritic cells found?
in tissues which are in contact with the environment: skin, lining of nose, lungs, stomach, and intestines
Which cell do activated macrophages present to?
helper T cells
How do T cells become activated?
must encounter antigen presented on cell in antigen-MHC complex
must also be concurrently stimulated by other molecules
Functions of activated T cells:
proliferate, develop into different effector cells
bring antigens to naive T cells
release lymphokines which acts as messengers, they do not respond to specific antigen, instead lymphokines act to recruit other cell types particularly macrophages
What do TH1 cells do?
judge antigen presented macrophages, if it recognizes the antigen it responds by activating the macrophage
they orchestrate the cell mediated response by releasing lymphokines to stimulate proliferation of T cells, stimulate natural killer cells, and recruit macrophages
What to TH2 cells do?
judge antigen presented by B cells
activated B cell to produce antibody
stimulate proliferation of B cells
What do T regulatory cells do?
block induction and activity of T helper cells and B cells
How is type IV hypersensitivity mediated?
cellular immunity
What are lymphokines?
cytokines released by lymphocytes that act as chemical messengers and activate other cell types
Which cells mediate humoral immunity?
B lymphocytes
What are the characteristics of antibodies?
produced by plasma cells (from B cells)
they are found in blood serum
interaction with antigen causes b cells to differentiate into plasma and memory cells
What is an antitoxin?
an antibody with the ability to neutralize a specific toxin
What is an opsonin?
any molecule that acts as a binding enhancer for the process of phagocytosis, antibodies can be opsonins
What part of the antibody binds antigen?
Fab, fragment binding portion
What part determines antibody class?
Fc, crystalline fragment, the stick part
Where is the variable region found?
the Fab region
Where is the constant region found?
the entire Fc region as well as one domain of both heavy and light chains in the Fab region
Which is the most abundant Ig?
IgG, aka gamma globulin
Which Ig crosses the placental barrier to provide passive immunity to fetus also in colostrum and breastmilk?
IgG
Which is the largest Ig?
IgM
Which Ig is the first class to be produced in response to antigen?
IgM
Which Ig can a fetus produce after 3 mo?
IgM
Which Ig is the most efficient class at activating the complement cascade?
IgM
Which Ig is foun din body secretions?
IgA
Which Ig can cause anaphylactic shock?
IgE
Which complement cascade is caused by antibody IgG or IgM binding to antigen?
classical pathway
Which complement pathway does not require antibody/antigen binding?
alternative pathway
Which complement pathway binds o sugars on the microbial surface?
Mannan-Binding Lectin pathway
What are the three possible actions of complements?
- opsonization
- release various active substances including chemotaxis and promotion of inflammatory response (attraction of phagocytes)
- cell lysis
Which class are the first antibodies produced during adaptive immune response?
IgM and IgG
Do all antigens require presentation?
no, some antigens are T cell dependent
What does T cell dependent antigen mean?
do not require presentation rather B cells respond directly to antigen
Are there more T cell independent or T cell independent antigens?
T cell dependent, which do require presentation to helper T cells
How long does the adaptive immune system require to respond during a primary exposure?
1 week or more
During the secondary response which Ig class is higher and longer lasting?
IgG
What does active immunization refer to?
immunity produced by the body following exposure to antigen, naturally or via vaccines
Which type of vaccine is unable to replicate but retains the immunogenicity of infectious agent or toxin?
inactivated (killed) vaccine
Which type of vaccine is a weakened form of disease-causing microbe that is unable to cause disease?
live attenuated vaccine
which vaccine type is composed of key protein antigens or antigenic fragments?
subunit vaccines
What is an advantage of the inactivated vaccine?
can’t revert to dangerous form
What does passive immunization refer to?
immunity acquired by receiving antibodies produced by another animal
Which type of immune hypersensitivity is associated with anaphylaxis?
Type I-Immediate Hypersensitivity
Which immune hypersensitivity has antigen-antibody complexes lodging in the capillaries between the endothelial cells and the basement membrane?
type III-Immune complex reactions
Which immune hypersensitivity is cell-mediated with T cells?
Type IV-delayed hypersensitivity
