chapter 13 (module 4) Flashcards
the adaptive immunity is the product of a dual system, the
T and B lymphocytes
the ability of the body to react with countless foreign substances
immunocompetence
molecules that can be seen and identified by the immune system
antigens
Antigens may or may not provoke an immune response after being sensed by the immune system, if they do provoke a response they can be called ________.
immunogens
these molecules are usually protein or polysaccharide molecules on or inside all cells or viruses
antigens
the precise molecular group of an antigen that defines its specificity and triggers the immune response
-> primary signal that a molecule is foreign
epitope
adaptive immunity
specificity***
response is focused on a single specific antigen
adaptive immunity
diversity
there is always at least one cell that can react against any antigem
adaptive immunity
inductibility
only turned on when triggered
adaptive immunity
tolerance
does not react with self antigens
adaptive immunity
clonality
generates millions of cells with same specificity
adaptive immunity
memory***
rapid mobilization of lymphocytes preprogrammed to recall their first engagement with the antigen
the elegance and complexity of immune function are largely due to _______ working closely with ________
lymphocytes and phagocytes
adaptive immune response
stage one: lymphocyte development and clonal deletion
- arise from the same stem cell type but diverge into T (thymus) and B cells (specialized bone marrow sites)
- T and B cells constantly migrate in and out of lymphoid organs
adaptive immunity
stage two: entrance and presentation of antigens and clonal selection
- foreign cells enters tissues
- tissue macros ingest it and may induce inflamm response
- tissue dendritic cells ingest the antigen and migrate it to the nearest lymphoid organ (often the lymph nodes)
- the lymphoid organs process the antigen and present it to T and B lymphocytes
- B cells may need help from Helper T cells to initiate response
role of markers
each have a distinct and significant role in detection, recognition, and cell communication
-serve to activate different components of immunity
a set of genes in mammals that produces molecules on surfaces of cells that differentiate among different individuals in the species
major histocompatibility complex (MHC)
this genes complex gives rise to a series of glycoproteins found on all cells except RBCs
also called the human leukocyte antigen (HLA)
MHC genes
major histocompatibility complex
three classes of MHC genes
- Class I genes code for markers that appear on all nucleated cells
- Class II MHC genes code for immune regulatory markers (found on macrophages, dendritic cells, and B cells, T cells)
- Class II MHC genes encode proteins involved with the complement system, among others.
CD molecules
cluster of differentiation, naming scheme for many of the cell surface molecules (well over 400 have been names)
lymphocyte markers
frequently called receptors because it emphasizes there major role in accepting or grasping antigens in some form
-B cells have receptors that bind antigens and T cells have receptors that bind antigens that have been processed and complexed with MHC molecules on their presenting cell surface
adaptive immunity
stage three: challenging B and T cells with antigens
- when challenged by an antigen B and T cells proliferate and differentiate
- the multiplication of a particular lymphocyte creates a clone, or group of genetically identical cells, some of which are memory cells that will ensure future reactiveness against that antigen
adaptive immunity
stage 3a: How T cells respond to antigen
-T cell types and responses are extremely varied
- when activated by an antigen, a T cell gives rise to a variety of different cells with different roles:
1. Helper T cells that activate macrophages, assist B cells, and help activate cytotoxic T cells
2. Regulatory T cells that control T-cell response by secreting anti-inflammatory cytokines or preventing proliferation
3. Cytotoxic T cells that lead to the destruction of infected host cells and other foreign cells
*T cells do not produce antibodies
adaptive immunity
Stage 3b: How B Cells Respond to Antigen: Release of Antibodies
when a B cell is activated or sensitized by an antigen, it DIVIDES, giving rise to plasma cells, each with the same reactive profile
- plasma cells release antibodies into the tissue and blood
- when these antibodies attach to the antigen for which they are specific, the antigen is marked for destruction or neutralization
13.2
Stage I: The development of Lymphocyte Diversity
t cells reach maturity in the thymus, and also the ___________
GI tract
In addition to the antigen-specific T cell receptor, all mature T lymphocytes express coreceptors called ___, which surround the T-cell receptor and assist in binding.
CD3
T cells express CD3, ___, or a ___ coreceptor.
CD4, CD8
___ is an accessory receptor protein mostly found on T Helper cells that helps the T cell receptor bind to MHC class II molecules
CD4
___ is mostly found on cytotoxic T cells, and it helps bind MHC class II molecules
CD8
Contrasting Properties of B and T Cells
Site of Maturation:
T- thymus
B- bone marrow
Specific Surface Markers:
T-T-cell receptor, several CD molecule
B- immunoglobulin
Circulation in Blood
T- high numbers
B- low numbers
Receptors for Antigens
T- T-cell receptor
B- B cell receptor (immunoglobulins)
Distribution in Lymphatic Organs
T- paracortical sites (interior to the follicles)
B- cortex (in follicles)
Require Antigen Presented with MHC
T- Yes
B- No
Product of Antigen Stimulation
T- several types of activated T cells and memory cells
B- plasma cells with memory cells
General Functions
T- cells activated to help other immune cells, suppress/kill abnormal cells, mediate hypersensitivity, synthesize cytokines
B- production of antibodies to inactivate, neutralize, target antigens
DiGeorge Syndrome
thymus deficiency
Severe Combined Immunodeficiency Syndromes (SCID)
group of genetic disorders resulting from defective hematopoietic precursor cells, causing a deficiency of both B and T lymphocytes
Cancer (thymomas and thymic lymphomas)
tumors that originate from thymic epithelial cells (thymomas)
tumors originating from thymocytes (thymic lymphomas)
primary tumors affecting the thymus
B cells develop in the bone marrow, and as a result of gene __________ and __________, hundreds of millions of distinct B cells develop
modification and selection
it is estimated that each human produces antibodies with ___ trillion different specificities.
10
large glycoprotein molecules that serve as the antigen receptors of B cells, and when secreted, as antibodies
-> the specific B-Cell receptor
immunoglobulins
specific regions at the ends of the antibody “Y” molecule that recognize specific antigens; highly variable in shape so they can fit a wide variety of antigens
antigen binding site
variable (V) region
the antigen-binding fragment of an immunoglobulin molecule, consisting of a combination of heavy and light chains whose molecular conformation is specific for the antigen
what process is responsible for the increase in numbers of lymphocytes?
clonal expansion after antigen encounter causes B cells and T cells to proliferate
receptor similarities and differences between B and T cells
T is similar to B in that
- its receptor is formed from genetic modification
- it has variable and constant regions
- it is inserted into the membrane
- it has an antigen binding site formed from parallel polypeptide chains
however, unlike the B cell receptor, T-cell receptor is relatively small and is NEVER secreted
a conceptual explanation for the development of lymphocyte specificity and variety during immune maturation
clonal selection
after activation, the B or T cell multiplies rapidly in a process called _______ _______
clonal expansion
what are the two important features of clonal selection?
- Lymphocyte specificity is preprogrammed, existing in the genetic makeup before an antigen has ever entered the tissues
- Each genetically distinct lymphocyte expresses only a single specificity and can react to that chemical epitope
the lymphocytes that develop a specificity for self molecules are eliminated in a process called _______ _______, and leads to ________ _________.
clonal deletion
immune tolerance
mitotic division of a specific lymphocyte expand into a larger population of lymphocytes all bearing the same specificity, with the goal to fight the specific epitope they recognized
clonal expansion
13.3 Stage II: Presentation of Antigens
an antigen must be perceived as ________
foreign
materials that serve as good immunogens
proteins and polypeptides (enzymes, cell surface structures, exotoxins)
lipoproteins (cell membranes)
glycoproteins (blood cell markers)
nucleoproteins (DNA complexed to proteins but not pure DNA)
polysaccharides (certain bacterial capsules) and lipopolysaccharides
characteristics of “good” immunogens (provoking a strong response)
a. their chemical composition
b. their context–meaning what type of cytokines are present
c. their size
we can generalize that ____ antigens are better than ____ antigens. however a large size alone is not sufficient for immunogenicity
- large
2. small
poor immunogens
trisaccharide
polypeptide
->small molecules and linear molecules are less likely to be good immunogens
an incomplete or partial antigen, cannot stimulate a full immune response
hepten
True or False
A hapten can link to a larger carrier molecule and the two combined can develop immunogenicity; the hepten serves as the epitope
true
List some examples of haptens
drugs, metals, and ordinarily innocuous household, industrial, and environmental chemicals
many haptens __________ develop antigenicity in the body by combining with larger molecules such as serum proteins
inappropriately
cell surface molecules and markers that occur in some members of the same species but not others
-> are the basis for an individual’s blood group and major histocompatibility profile = responsible for incompatibilities that can occur in blood transfusion or organ grafting
Alloantigens
bacterial toxins that are potent stimuli for T cells and can be a factor in diseases such as toxic shock
->their presence can activate T cells at a rate 100 times greater than ordinary antigens = the result can be an overwhelming release of cytokines and cell death
superantigens
antigens that evoke allergic reactions
allergens
cells that grab the antigen-carrying microbe and ingest it, degrade it, and pass it’s antigens back out onto their membranes complexed with MHC-I or MHC-II markers, and then presented to T lymphocytes
antigen-presenting cells (APCs)
what three cells are APCs?
B cells, macrophages, and dendritic cells
-> dendritic being the most potent
most antigens must first be presented to T cells, even though they will eventually activate T and B cell systems.
However, a few antigens can trigger a response directly from B lymphocytes without APCs or T helper cells, what are these called?
T-cell-independent antigens
usually simple molecules such as carbs with many repeating and invariable determinant groups
ie. lipopolysaccharide from the cell wall of E. coli or polysaccharide from the capsule of Streptococcus pneumoniae, and molecules from rabies and Epstein-Barr virus
T-cell-independent antigens
list characteristics of antigens that optimize their immunogenicity
- Chemical composition
- Size
- what types of cytokines are present
list the types of cells that can act as antigen presenting cells
- Dendritic cells
- Macrophages
- B cells
describe how the immune system responds to alloantigens and superantigens
superantigens: activates an on overwhelming response from T cells causing cell death and too much release of cytokines ie. toxic shock
alloantigens: can cause incompatibilities during organ grafting and blood transfusions, can cause self-attack
13.4 Stages III and IV: T-Cell Response
why are T cells referred to as “restricted”
they require some type of MHC (self) recognition before they can be activated
what is the result of T cell stimulation?
mobilization of other T cells, B cells, and phagocytes
Memory T cells are some of the ______-_____ blood cells known
longest-lived
T Helper Cell 1
Co-receptor(s): CD4
Function:
- activates the cell-mediated immunity pathway
- secretes tumor necrosis factor and interferon gamma
- responsible for delayed hypersensitivity (allergy occurring several hours or days after contact)
- secretes IL-2
T Helper Cell 2
Co-receptor(s): CD4
Function:
- can activate macrophages to expel helminths or protozoans, phagocytose extracellular antigens
- contributes to type 1 (allergic) hypersensitivity
- can encourage tumor development
T Helper Cell 17
Co-receptor(s): CD4
Function:
-promotes inflammation
T Follicular Helper Cell
Co-receptor(s): CD4, CD40L
Function:
- drives B-cell proliferation
- aids B cells in antibody switching class
T Regulatory Cell
Co-receptor(s): CD4, CD25
Function:
- controls adaptive immunity response
- prevents autoimmunity
- can contribute to cancer progression
T Cytotoxic Cell
Co-receptor(s): CD8
Function:
- destroys a target foreign cell by lysis
- important in destruction of complex microbes, cancer cells, virus-infected cells
- graft rejection
- requires MHC-I for function
Gamma-delta T cells
Function:
- react in the innate and adaptive systems
- responsive to lipid antigens
general overview of Helper T cells
- they all bear the CD4 marker
- critical in regulating immune reactions to antigens (B and T cells)
- activate macrophages both directly (receptor contact) and indirectly (by releasing cytokines like interferon gamma)
- some T helper cells secrete IL-2 and some secrete IL-4, 5, 6
**most prevalent type of T cell in the blood and lymphoid organs, making up about 65% of the T cell population
->the severe depression of T helper cells by HIV is what largely accounts for the pathology of AIDS
proteins released by cytotoxic T cells that produce pores in target cells
perforin
enzymes secreted by cytotoxic T cells that damage proteins of target cells
granzymes
a T lymphocyte programmed to directly affix cells and kill them
-for this cell to be activated it must recognize a foreign peptide complexed with self MHC-I and mount a direct attack upon the target cell; involves the secretion of perforins (punch holes in target cell membranes) and granzymes (enter said pores and attack proteins)
Killer T cells
cytotoxic T cells have one job: to destroy other cells such as what
virally infected cells - recognize telltale virus peptides expressed on virus surface (also target cells carrying intracellular bacteria)
cancer cells - attack any abnormal cells they encounter in the tissues (this fx is clearly seen in the susceptibility of T-cell-deficient people to cancer)
cells from other animals and humans - most important factor in graft rejection (attack foreign tissues that have been implanted into a recipient’s body)
what two types of T cells are always present in any given immune response?
T Helper cells and T Cytotoxic cells
T cells that are considered a bridge between the innate and adaptive immune responses due to the fact that they respond to certain kinds of PAMPs on microorganisms the way WBCs in the innate system do
-> particularly responsive to certain types of phospholipids and can recognize and react against tumor cells
Gamma-delta T Cells
type of lymphocyte related to T cells that lack specificity for antigens; they circulate the spleen, blood, and lungs, and are probably the first killer cells to attack cancer cells and virus-infected cells
-> destroy cells by similar mechanisms as T cells, but are not considered a part of the adaptive system
Natural Killer (NK) cells
hybrid kind of cells that is part killer cell and part T Cell, with T cell receptors for antigen and the ability to release large amounts of cytokine very quickly -> leading to cell death
= are considered to be a another important link between innate and adaptive immunity
Natural Killer T Cells (NKT Cells)
T cell system overview
T cells differentiate into five different types of cells (and also memory cells), each of which contributes to the orchestrated immune response, under the influence of a multitude of cytokines
13.4 Outcome
describe the main differences between T helper cells and C cytotoxic cells
The key difference between T helper cells and cytotoxic cells is that helper T cells are involved in coordination of the immune response against the pathogen with B cells and other T cells…..
while cytotoxic cells directly kill or destroy cancer cells and infected cells.
note the similarities and differences between gamma-delta T cells an other T cells
- gamma-delts t cells are much faster because they respond to certain kinds of PAMPs
- they both have t cell receptors, memory cells
13.5 Stages III and IV: B-Cell Response
the two arms that bind antigen are termed what
antigen binding fragments (Fabs)
composite of four polypeptide chains, a pair of identical heavy (H) chains and a pair of identical light (L) chains, and the two heavy chains are bonded to one another with disulfide bonds
“Y” shaped arrangement
immunoglobulin
what is at the end of each Fab fragment?
epitope
T or F
Fab fragments can change their angle to accommodate nearby antigen sites that vary slightly in distance and position
TRUE
the site on the antibody where the epitope binds is composed of a ________________, whose amino acid content can be extremely VARIED
hypervariable region
principal activity of an antibody
to immobilize, call attention to, or neutralize the antigen for which it was formed
= job of antibody is to ruin antigen
a process that makes microbes more readily recognized by phagocytes so that they can dispose of them
opsonization
performed by antibodies called opsonins
in _______ reactions, antibodies fill the surface receptors on a virus or the active site on a microbial enzyme to prevent it from attaching normally
neutralization
an ________ is a special type of antibody that neutralizes bacterial exotoxins
antitoxin
________ is the result of antibodies cross-linking cells or particles into large clumps, and rendering the microbes immobile and enhances phagocytosis
agglutination of antigens
the interaction of an antibody with complement can result in what?
the specific rupturing of cells and some viruses
Fc
the portion of the antibody below the Fabs
crystallized fragment the bottom portion of the “Y”
structural and functional classes of immunoglobulins
isotypes
The Fc end of an antigen can bind to receptors on the membranes of cells, such as macrophages, neutrophils, eosinophils, mast cells, basophils, and lymphocytes.
-> the effect of an antibody’s Fc end binding to a cells depends on _______
that cell’s role
The Fc end of the antibody of allergy (IgE) binds to basophils and mast cells, which causes the release of allergic mediators such as _____
histamine
IgG
- Monomer
- 2 binding sites
- % of total antibody in serum: 80%
- average half life in serum (days): 23
- crosses placenta
- Fc binds to phagocytes
- most prevalent antibody
-produced in primary response, neutralizes toxins, opsonizes, fixes complement
IgA
- number of antigen binding sites: 4,2
- % of total antibody in serum: 13%
- average half life in days: 6
- the dimer, secretory IgA, is formed by two monomers held together by a J chain
- dimer is secretory antibody on mucous membranes
- monomer is in small quantities in blood
- high amount of IgA in colostrum
- provides the most important adaptive local immunity to enteric, resp, and genitourinary pathogens
IgM
- 10 antigen binding sites
- % of total antibody in serum: 6%
- average half life in serum in days: 5
- fixes complement
-produced at first response to antigen, it can serve as a B-cell receptor
complement-fixing antibody
antibody that combines with antigen leading to the binding and activation of complement, which may result in opsonization or cell lysis
IgD
- 2 antigen binding sites
- % of total antibody in serum: 1%
- average half life in serum in days: 3
- pentamer
-is the receptor on B-cells and a triggering molecule for B cell activation
IgE
- 2 antigen binding sites
- % of total antibody in serum: 0.002%
- average half life in serum in days: 2.5
- Fc binds to mast cells and basophils
- antibody of allergy and of worm infections
- it also mediates anaphylaxis, asthma, etc.
a blood protein produced in response to and counteracting a specific antigen
antibody
concentration of antibodies; determined by agglutination methods
titer
the first response of the immune system when exposed to an antigen
primary response
the rapid rise in antibody titer following a repeat exposure to an antigen that has been recognized from a previous exposure; this response is brought on by memory cells produced as a result of the primary exposure
secondary response
another name for secondary response; an augmented response or memory r/t a prior stimulation of the immune system by antigen, it boosts the level of immune substances
anamnestic response
latent phase of primary response
lack of antibodies for antigen, but the antigen is being processed by the correct clones of B lymphocytes
what antibody is most prevalent early in the primary response?
IgM (first class to be secreted by the plasma cells)
later in the primary phase, IgM changes over to mostly what antibody?
IgG or some other class (IgA or IgE)
-> remember, IgG is produced in a primary response and by memory cells (table 13.8)
what is now known about memory cells r/t the previous thought that memory B and T cells are only created from clones activated by a specific antigen?
it seems that exposure to a particular antigen can result in memory cells that will recognize antigens that are chemically related to it, even if those antigens have not been seen by the host
- > this makes sense: adaptive immunity occurs via recognition of epitopes, so if other microbes share those same chemical signatures (epitopes), memory cells will react against them as well
ie. in Africa, vaccinating against measles also cuts death rates from pneumonia, sepsis, and diarrhea by one third
B cell activation
- antigen binds to reg. B cell
- antigen is endocytosed by the B cell and degraded into smaller peptide determinants -> the antigen is then bound to the MHC-II receptors on the surface of B cell
- most B cell must interact with already activated T Helper cell, they engage in linked recognition
- the combination of these stimuli on the membrane receptors causes a signal to be transmitted internally to the B cell nucleus -> B cell activation
- differentiation -> regulatory cells, plasma cells, and memory B cells are produced
- clonal expansion -> each type of cell expands its population by mitosis (memory cells seed the lymphatic circulation, reg cells proliferate and secrete IL-10 to regulate T cell response, plasma cells)
only antibody that crosses the placental barrier, and Fc binds to phagocytes; most prevalent antibody
IgG
IgG, IgE, IgM, IgA, IgD
isotypes of antibodies
immunity can be natural or __________, and it can be either active or _______.
artificial
passive
any immunity that is acquired during the normal biological experiences of an individual rather than through medical intervention
natural immunity
protection from infection obtained through medical procedures; induced by immunization with vaccines and immune serums
artificial immunity
occurs when an individual receives an immune stimulus (antigen) that activates the B and T cells, causing the body to produce immune substances such as antibodies
active immunity
characteristics of active immunity
- creates a memory that renders the person ready for quick action upon re-exposure to the same antigen
- it requires several days to develop
- it lasts for a relatively long time, sometimes for life
* can be stimulated by natural or artificial means
occurs when an individual receives immune substances (usually anti-bodies) that were produced actively in the body of another animal or human donor; recipient is protected for a short time, even though he or she has not had prior exposure to the antigen
passive immunity
characteristics of passive immunity
- lack of memory for the original antigen
- lack of production of new antibodies against the disease
- immediate onset of production (individual receives immune substances immediately, ie. antibodies)
- short-term effectiveness because antibodies have limited time period of function, and ultimately, the recipient’s body disposes of them
*can be natural or artificial in origin
immunity that is for a short period of time, but offers immediate immunity
passive
give an example of natural passive immunity
prenatal/postnatal mother-child relationship
- > IgG antibodies circulating in the maternal bloodstream can pass through the placenta
- > IgA in Mother’s milk, provide special type of intestinal immunity
example of natural active immunity
after recovering from an infectious disease like the seasonal flu, and building immunity for it
give an example of artificial active immunity
vaccination
give an example of artificial passive immunity
involves a preparation that contains a particular infectious agent;
- pooled human serum from donor blood (gamma globulin)
- immune serum globulins containing high quantities of of antibodies
convalescent serum and SARS-CoV-2
serum containing antibodies from people who were ill with SARS-CoV-2 and had recovered
-> this approach is useful when there is no vaccine yet available
a hazardous, outmoded process deliberately introducing smallpox material scraped from a victim into the nonimmune subject in hope of inducing resistance (10th century attempt at immunization)
variolation
term originally used in reference to inoculation with the cowpox or vaccinia virus to protect against small pox; in general the term now pertains to injection of whole microbes (killed or attenuated), toxoids, or parts of microbes as a prevention or cure for disease
vaccine
phase I of vaccine clinical trials
20-100 healthy volunteers
- is this vaccine safe
- does it seem to work
- are there any serious side effects
- how is the size of the dose related to side effects
phase II of clinical trials
several hundreds of volunteers
- what are the common short-term side effects
- how are the volunteer’s immune systems responding to the vaccine
phase III of clinical trials
hundreds or thousands of volunteers
- how do people who get the vaccine and people who do not get the vaccine compare
- is the vaccine safe
- is the vaccine effective
- what are the most common side effects
the FDA licenses a vaccine only if:
- it’s safe and effective
- its benefits outweigh its risks
vaccines are made in batches called ____.
lots
what are the only two natural forms of passive immunity
- through placenta
2. through breastmilk (IgA)
Intravenous immunoglobulin (IVIG)
sometimes called gamma globulin
-contains immunoglobulin extracted from the pooled blood of human donors
method of processing IVIG
concentrates the antibodies to increase potency and eliminates potential pathogens such as HIV and Hep B
What patients is IVIG most useful in?
patients who have a diminished ability to mount their own immune response, or if the disease is so fast acting that it could be fatal before the victim develops their own antibodies (tetanus, rabies)
specific immune globulin (SIG)
derived from a more defined group of donors; derived from patients who are convalescing and in a hyperimmune state after infections such as Hep B, pertussis, tetanus, chicken pox
why is SIG preferable over IVIG?
because SIG contains higher titers of specific antibodies obtained from a smaller pool of patients
basic principle behind vaccination
to stimulate a primary response and a memory response that primes the immune system for future exposure to a virulent pathogen
qualities of an ideal vaccine
- it should protect against exposure to natural, wild forms of the pathogen
- it should have a low level of adverse side effects or toxicity and not cause harm
- it should stimulate both antibody (B-cell) response and cell-mediated (T-Cell) response
- it should have long-term, lasting effects (produce memory)
- it should not require numerous doses or boosters
- it should be inexpensive, have a relatively long shelf life, and be easy to administer
vaccines can be broadly categorized as either whole-organism or
part-of-organism
subcategories of vaccine preparations
- Whole cells or viruses
a. live, attenuated microbial cells or viruses
b. killed cells or inactivated cells - Part-of-organism preparations: antigen molecules derived from bacterial cells or viruses (subunits)
a. subunits derived from cultures of cells or viruses
b. subunits chemically synthesized to mimic natural molecules found on pathogens
c. subunits manufactured via genetic engineering
d. subunits conjugated with carrier proteins (often from other microbes) to make them more immunogenic -> these are called conjugated viruses
Whole Cell Vaccines
a. live, attenuated microbial cells or viruses
virulence is eliminated or reduced -> alive, with same antigenicity -> administer -> vaccine microbes can multiply and boost immune system
ie. measles, mumps, rubella, polio, contain live nonvirulent viruses
Whole Cell Vaccines
b. killed or inactivated virus
antigens -> heat or chemicals -> dead, but antigenicity is retained -> vaccine stimulates immunity but pathogen cannot multiply
ie. Hep A vaccine, three forms of the influenza vaccine contain inactivated viruses
because the microbes does not multiply inside the host, ______ vaccines often require a larger dose and more boosters to be effective
killed vaccines
attenuated meaning
lessened or eliminated
disadvantage of using live microbes in vaccines
they require special storage facilities and could conceivably mutate back to become virulent again
advantages of live preparation vaccines
- viable microorganisms can multiply and produce infection (but not disease) like the natural organism
- they confer long-lasting protection
- they usually require fewer doses and boosters than other types of vaccines
- they are particularly effective at cell-mediated immunity
subunit vaccines (parts of organisms)
if the exact epitopes that stimulate immunity are known, it is possible to produce a vaccine based on a selected component of a microorganism
- > the antigens used in these vaccines may be taken from cultures of the microbes, produced by genetic engineering, or chemically synthesized
ie. examples of components used are the capsules of pneumococcus and meningococcus, the surface protein of anthrax, and the surface proteins of Hep B virus.
toxoid vaccine
a toxin that has been rendered nontoxic but is still capable of eliciting the formation of protective antitoxin antibodies; used in vaccines
- > purified bacterial exotoxin that has been chemically denatured
ie. vaccines for diphtheria, tetanus, and pertussis
DNA vaccines
DNA from a pathogen is inserted into a plasmid vector and inoculated into a recipient with the expectation that the human cells will take up some of the plasmids and express the foreign DNA in the form of proteins
- > b/c the proteins are foreign, they will be recognized during immune surveillance and cause B and T cells to be sensitized and form memory cells.
- currently there are more than 500 DNA vaccines in trial
immunotherapy for cancer
T cells or dendritic cells are removed from the patient
- > in a lab the cells are sensitized to known cancer antigens
- > the now activated cells are injected back into the patients in the hopes that the actual tumor antigens match the ones used for activation in the lab and the patients own immune system will attack the tumor
this vaccine route can stimulate protection (IgA) on the mucous membrane of the portal of entry, and are also easier to give than injections and are more readily accepted
oral or nasal route administration
any compound that enhances immunogenicity and prolongs antigen retention at the injection site
-> precipitates the antigen and holds it in the tissues so that it will be released gradually
adjuvant
some vaccines require the addition of a special binding substance, or __________.
adjuvant
a chemical vehicle that enhances antigenicity, presumably by prolonging antigen retention at the injection site
adjuvant
more serious reactions in vaccines are extremely rare: fewer than 1 case in ______
220,000
thimerosal
phased out preservative used in vaccines that is thought to cause allergies and other potentially harmful side effects
some patients experience allergic reactions to the _____ used to grow the vaccine organism ie. eggs or tissue culture
medium
a phenomenon in which a certain amount of the population is vaccinated, preventing the microbes from circulating through the population
herd immunity
outcome 13.6
qualities of an ideal vaccine
- protects against exposure to natural and wild forms of the pathogen
- low level of adverse effects or toxicity and not cause harm
- should stimulate antibody B cell response and cell-mediated T cell response
- should not require numerous doses or boosters
- should be inexpensive, long shelf-life, easy to admin
- should have long-term lasting effects
outcome 13.6
four types of immunity
natural passive - placenta, breast milk (short term/immediate)
natural active - getting the seasonal flu and building immunity (long term)
artificial passive - immunotherapy (short term/immediate)
artificial active - vaccination (long term/in time)
outcome 13.6
name the two major categories of vaccines + their subcats
whole cell/virus vaccines
a. live, attenuated vaccines ie. measles
b. killed, inactivated ie. Hep A
subunit vaccines
a. derived from cultures of cells or viruses
b. subunits chemically synthesized to mimic natural molecules found on pathos
c. subunits manufactured via genetic eng
d. subunits conjugated with proteins to make them more immunogenic (conjugated vaccines)
ie. capsules of pneumococcus and meningococcus
a single bacterium has _______ epitope(s)
a. a single
b. multiple
c. MHC
d. clonal
b. multiple
the primary B cell receptor is
a. IgD
b. IgA
c. IgE
d. IgG
a. IgD
some microbial products can activate B cells without the assistance of T cells. Which of the following can do this?
a. Capsule of S. pneumoniae
b. lipopolysaccharide
c. some viral capsids
d. all of these
d. all of these
if you draw a blood sample from a patient to determine whether he or she has herpes simplex infection, and the patient displays a large amount of IgG against the virus but low levels of IgM, what do you conclude?
the patient has had the infection for a while
IgM
produced at first response to antigen
