Over view of the immune system Flashcards
immunity
derived from the latin word immunis, which referred to the exemption from various civic duties and legal prosecutions granted to roman senators during their terms in office.
all multicellular organisms have developed various mechanisms for defending themselves against ________ collectively, they constitute the immune system.
foreign invaders
invertebrates have what type of immunity?
innate immunity
Vertebrates have what type of immunity?
innate and adaptive immunity
what are other names for innate immunity?
natural
native
nonspecific
characteristic’s of innate immunity
present in all individuals or animals at all times no memory (does not improve on repeated exposure) does not discriminate between pathogens first and second lines of host defense
other names for adaptive immunity
acquired
specific
characteristics of adaptive immunity
mediated by T and B lymphocytes
highly specific for a particular pathogen
takes several days for it to become fully functional
improves with successive encounter with the same pathogen
third line host defense
immunologic memory
improves with successive encounter with the same pathogen
T or F: acquired immunity does not opperae independently of innate immunity.
T
it supplements and augments the nonspecific defense mechanism, producing a more effective total response
the first line of defense
intact skin
mucous membranes and their secretions
normal flora
second line of defense
neutrophils, macrophages
phagocytosis
inflammation and fever
antimicrobial substances
components of innate immunity
age skin oral cavity Respiratory tract eyes genitourinary tract normal flora iron binding proteins oxygen tension complement interferons temperature inflamation
Age
very young and very old are more susceptible to infection b/c immune response is suboptimal
poor nutrition do to not being able to smell or taste any more can lead to vitamin deficiencies
protein, vitamins, and b complexes are need for a healthy immune response
skin
mechanical barrier
epithelial produce ____ that have a natural antibiotic function (defensins)
peptides
in humans the epidermis is completely renewed every
and this is know as what
15-30 days
epithelial turnover
sebum
produced by sebaceous glands
protective film over surface o skin
contains lactic acid and fatty acids that inhibit growth of microorganisms
pH3-5
perspiration
flushes microorganisms from the surface of the skin
sweat contains lysozyme
oral cavity
saliva washes microorganisms from teeth and gums
contains antibacterial agents; lysozymes
gastrointestinal tract
low pH of the stomach
normal flora
peristaltic movement- vomiting diarrhea
proteolytic enzymes, bile acids, and pancreatic secretions
respiratory tract
mucocilliary escalator
coughing and sneezing (speeds up the escalator)
alveolar macrophages
eyes
flushing action of tears (contain lysozyme)
genitourinary tract
urine. flushing action of urine; acidity of urine (contains lysozyme)
vaginal lactic acid
normal flora
microorganisms ( mostly bacteria, fungi, protozoa) that colonize a host with out causing disease
some may cause disease under certain circumstances
contribute to host defense by preventing potential pathogens from colonizing the host
competition for attachment sites and nutrients
produce substances harmful to pathogens; bacteriocins
E. coli in the LI produce colicins that inhibit thegrowth
of Salmonella spp and Shigella spp.
altering conditions that affect the survival of pathogens;
pH and O2 availability
lactobacillus acidophilus in the vagina alters is pH
to prevent over population by Candida albicans
bacteriocins
antimicrobial peptides produced by bacteria that kill or inhibit other bacteria
competitive exclusion
proposition that states that 2 species competing for the same resources cannot coexist if other ecological factors are constant
iron binding proteins
proteins that sequester iron thereby reducing iron available to a pathogen, eg, transferrin, lactofeerin, and haptoglobin
iron plays a critical roll in bacterial respiration as a component of the ________ and _____________ involved in electro transport
cytochromes and iron-sulfide proteins
siderophores
iron- chelating compounds produced by various pathogenic bacteria that facilitate the uptake of iron by the bacterial cell
oxygen tension
inhibits the growth of obligate anaerobic bacteria, especially in the lungs
complement
plasma and cell surface proteins associated with lysis of gram negative bacteria, chemotaxis of phagocytes, and opsonization
opsonization
the coating of an antigen or particle that facilitates its uptake into a phagocytic cell
interferons
low molecular weight glycoproteins produced by certain cells in response to viral infections
IFNs have ______ and _____ activity
antiviral and immune regulatory
temperature
body temperature inhibits replication of some pathogens
fever enhances phagocytosis
antibody production and T cell proliferation are more efficient at higher body temps than at normal levels
fever can be induced by
bacterial endotoxin (lipopolysaccharides) interleukin-1
inflamation
begins following sublethal injury to tissue and ends with complete healing
cause may be microbiological, physical, or chemical
results in the brining of blood components and cells of the immune system to the site of tissue damage
components of specific immunity
antibody-mediated( humoral) immunity
cell- mediated immunity
antibody- mediated (humoral) immunity
antibodies are made by the interaction between a Blymphocyte and an antigen
they are soluble proteins
once made have the ability to combine with the antigen that stimulated its production
antibodies are found in
plasma
lymph
tissue fluids
antibodies are effective in eliminating
extracellular antigens and bacterial toxins
cell mediated immunity
antigen specific T cells play the main role
Macrophages and natural killer cells, and nonspecific cells
CMI responses are most important against _____ ______, in ____ ____, and in ____ _____ _____.
intracellular parasites
allograft rejection
delayed hypersensitivity reactions
adaptive immune response is divided into 3 phases:
- recognition of antigen by antigen specific lymphocytes
- activation of lymphocytes
- effector phase which results in destruction of the antigen
activation of lymphocytes results in
clonal expansion
Clonal expansion
the proliferation of antigen-specific T and B lymphocytes in response to antigenic stimulation and precedes their differentiation into effector cells and memory cells.
cellular elements of blood, including the white blood cells of the immune system, platelets and RBC are derived from the same progenitor cells, which are
hematopoietic stem cells in the bone marrow
what are the two main lines of differentiation of pluripotent stem cells
myeloid lineage
lymphoid lineage
myeloid lineage
produces monocytes, neutrophils, basophils, eosinophils and other cells
lymphoid lineage
produces lymphocytes
plasma proteins
a mixture of a number of proteins of different structural and functional properties
what are the major plasma protein
albumin, fibrinogen and globulin
all of fibrinogen and albumin and 50-80% of globulins are produced where
liver
the remaining globulin proteins( gamma)are produced where
lymphoid organs and tissues
globulins
responsible for bodys innate and adaptive immune response against invading pathogens
Globulins are comprised of
complement proteins and antibodies
Host immune responses can result in the following:
autoimmunity
immunodeficiency
hypersensitivity
transplantation
autoimmunity
the response is directed against self- antigens
immunodeficiency
ineffective immune response
hypersensativity
overactive immune response resulting in allergies
transplantation reaction
rejection of allograft
cluster of differentiation( CD) molecules
are cell surface molecules expressed on a variety of cell types in the immune system
how are CD molecules identified
monocolonal antibody
they may be used as markers to differentiate different cell populations such as CD4+T cell( T helper cell) or CD8+ T cell( cytolytic T lymphocyte
antigen
any substance that can induce humoral and/or cell-mediated immune responses when introduced into an individual or animal
characteristics of antigens
must be able to react with specific receptors on B and T cells and with bodies produced against it
microbial antigen
bacteria fungi viruses protozoa helminth parasites
non microbial antigens
foreign proteins
food antigens
plant antigens
cell surface proteins
the degree of antigenicity of a molecule is influenced by several factors. they include:
foreignness chemical complexity molecular size stability degradability genetic make up of the host method of administration
foreignness
self vs. nonself
the macromolecule must come from a foreign cource
the more foreign the antigen the more vigorous the immune response
autologous antigens
antigens found within the same individual
syngeneic (isogeneic) antigens
antigens found in genetically identical individuals, eg, identical twins or inbred strains of mice
allogeneic antigens
antigens found in genetically dissimilar members of the same species, eg, blood- group antigens
xenogeneic antigens
antigens found in different species
chemical complexity
the more complex a molecule the more varied the epitope composition, hence the more likely different immune responses will be induced
epitope
antigenic determinant
proteins
most complex organic compounds
most antigenic
18 or more amino acids
the diversit imparts epitopes of differing specificities to the protein
polsaccharides
simple ones are weak antigens b/c they do not possess sufficient chemical complexity
rapidly degraded before the immune system has had time to respond to them
more complex polysaccharides
antigenic, eg, capsular polysaccharides and lipopolysaccharides
T or F:
antigenicity of poly saccharides is enhanced if they are coupled to proteins as glycoproteins.
true
lipids
weak antigens
due to their structural simplicity and rapid metabolism
immune response may be enhanced when they are conjugated to proteins (lipoproteins) or polysaccharides ( glycolipids)
molecular size
most potent antigens are proteins with high molecular weights above 100,000
in general, molecules with molecular weight ___ 10,000 are ___ antigenic, and very ____ ones, eg, amino acids are ________
below
weakly
small
non- antigenic
the ___ and ___ _____ _____ increases proportionately with the size of the protein
number
variety of epitopes
carbohydrate antigens
the number of epitopes increases with size but the diversity usually does not
stability
lymphocyte antigen receptors recognize an antigen by its shape. thus highly flexible molecules that have no fixed shape are poor antigens
degradability
T cells respond only to processed antigens
T or F:
antigen-presenting cells must firstdegrade the antigen before they can express antigenic peptides noncovalently bound to MHC on their cell surface.
T
Macromolecules that cannot be ___ and ___ with MHC molecules are ____ antigens
degraded
presented
poor
genetic make up of the Host
the genetic constitution of the host determines whether a given molecule will stimulate an immune response
* different strains of the same species of an animal may respond differently to the same antigen
method of administration
dosage
low doses
of an antigen may not stimulate an immune response either b/c
the amount given fails to activate enough lymphocytes or
renders the lymphocytes unresponsivness
very high doses
may lead to immune paralysis
route
of antigen administration determines which organs and cell populations will initiate the immune response
antigen presentations subqu
usually elicits the strongest response
the antigen is taken up by Langerhans cells in the skin, carried to
local lymph nodes, where they are processed and presented to
Tcells
epitopes
are the sites on or within the antigen that stimulate the immune response and against which that response is directed
epitopes determine
the specificity of the antigen molecule
internal epitopes
only expressed after the antigen has been partially degraded in vivo by antigen -presenting cells
polyvalent
many epitopes of different specificities
multivalent
many epitopes of the same specificity
accessibility of the epitopes
since hydrolytic products of the antigen generated by antigen
presenting cells contain various epitopes, immune responses are
generated against both
internal and surface epitopes
however only those epitopes on the ____ of the ____ ____ are able to bind to their antibodies.
outside
parent molecule
another name for cross- reactivity is
heterophile antigens
T or F:
some times an antibody produced to one antigen can cross- react with an unrelated antigen
T
Cross- reactivity is possible because
the two unrelated antigens share one or more identical or very similar epitopes. in the case of similar epitopes the affinity of the antibody for the cross reacting epitope is usually less than that for the original epitope
cross reactivity provides the basis for:
auto immune diseases ( molecular mimicry) heterologous vaccines (measles vaccine protects against canine distemper) false positive diagnosis
B cell receptor
cell surface receptor of B cells that recognizes a specific antigens
B cell receptors consist of
membrane immunolobulin molecule in association with the single transduction molecules Ig alpha and IG beta
T cell receptorts
cell surface receptor of T cells that binds to antigenic peptide presented in association with major histocompatibility complex molecule
T cell receptors consists of
alpha and beta protein chains that associate with the single transduction molecules CD3 plus zeta
major histocompatability complex (MHC)
are proteins encoded by MHC gene
classified as classI classII and classIII MHC molecules
class I and class II are cell surface molecules thet present antigenic peptides to T cellsHaptens
nonatigenic molecule , usually of low molecular weight
by itself can not induce an immune response, but can react with the products of that response
haptens include
antibodies
analgesics
poison ivy
to induce an immune response a hapten must always be coupled to a
carrier substance, preferably protein antigen!
hapten acts as a new pitope of the carrier protein and an immune response is generated to both the hapten and native epitopes of the protein
carrier proteins include
serum albumin, globulins, and synthetic polpeptides
T or F:
antibody specific for a given hapten can recognize and bind the hapten whether the hapten is free or bound to a carrier substance
T
Significance of Haptens
Karl landsteiner is credited with most of the work with haptens. his findings illustrate the diversity of the immune response and specificity of antigen - antibody and antigen -T cell reactions, ie, paul elrichs lock and key method
autocoupling haptens
have the ability to form spontaneous covalent bonds with self proteins to create neoatigens in vivo
its responses can have serious consequences in the body
poison ivy
the resin of posion ivy binds to any protein it comes incontact
with, including skin proteins. the modified skin proteins are
regarded as foreign and attacked by lymphocytes and an
allergic contact dermatitis results
