Ch 15 Specific Immunity Flashcards
Specific immunity has two subcategories, what are they?
Humoral immunity and cell mediated immunity
What is specific immunity
Ability to resist particular disease or foreign bodies. Recognition of foreign antigens and act to eliminate them in 2 ways.
Define humoral immunity
Formation of antibodies in response to antigens
Define cell mediated immunity
Direct destruction of an infected cell; “cell wars”
Define immunocompetence
Time period In fetal development when lymphocytes specialized to be reactive against 1 million or more foreign antigens. “Genetic programming”
What is acquired immunity
Immunity develops after exposure to foreign antigen; is individualized
Three characteristics of acquired immunity
Highly specific; develop memory for the future so second response is faster; tolerance (ability to distinguish self vs nonself)
What are Immunogens
Substances that induce the immune response: either antibody formation or activation of the cell mediated immunity or both. Must meet requirements of foreignness, size, shape and accessibility
What is an antigen
Large complex macromolecules; ex: proteins (strong), polysaccharides (weak). Could be capsules, viral capsids/envelopes, outer membrane molecules (LPS, flagella, etc); surface cells of fungi and helminths
What is an allergen
An antigen that stimulates an allergic response
What is a superantigen and give an example
Provokes an overwhelming response, can lead to sell shock, organ damage: toxic shock.
Ex: S. aureus
What is an epitope
Antigenic determining site; stimulate antibody formation and combine with them. “Sweet spot”
Antigenic receptors on B & T cells will recognize this and bind to them
What are haptens? Give an example
Not antigenic alone, become antigenic when bonded to a larger carrier molecule. (The combination of the two together is what becomes recognizable) Ex: penicillin
What are immunoglobulins
Group of glycoproteins present on the surface of B cell, they can be released as antibodies in blood serum and tissue fluid of mammals
_____ are found on the surface of B cells.
they become _____ when secreted.
Immunoglobulins on the surface of cells.
become antibodies when secreted.
Name the five classes of immunoglobulins
IgG, IgA, IgM, IgD, IgE
IgG
80%; Gamma globulins; circulating, cross placenta, help phagocytes activate complements, long-term memory, neutralize toxins and viruses. most important
IgA
Help with passive immunity; Second most important immunoglobulin
Describe the structure of IgG
Quaternary protein bound to a carbohydrate- glycoprotein; consists of four separate polypeptide chains
IgG consists of four chains. Describe them and their bond
2 heavy and 2 light; held together by disulfide cross bridges
Describe the constant region of the IgG structure
Does not vary between antibodies of the same class
Describe the variable region of the IgG structure
Antigenic combining sites, specific for the antigen
Humans can make antibodies against 100 million different antigens but they do not have that many genes to code for them. How do they have the genetic ability?
They are able to rearrange genetic components to create an infinite variety
Specific immunity involves which two types of lymphocytes
T cells and B cells
T cells mature where
In the thymus
Describe the helper T cell function
Stimulate or activate B cell and cytotoxic T cells; CD4 coreceptor
Describe the cytotoxic T cells function
Killer T cell; secrete toxic substances that cause infected cells to commit suicide; apoptosis; cell programmed death; CD8 coreceptor
Describe the memory T cells function
To remember the antigen
Describe the suppressor T cell function
Regulate response, shut it down
Where do B cells mature
In the bone marrow
B cells differentiate into what to cells
Plasma cells and memory cells
What is the function of a plasma cell
Make antibodies during primary response
What is the function of a memory cell
Make antibodies during the secondary response
What cells are involved in cell mediated immunity
T cells
What cells are involved in humoral immunity
B cells
What are MHC’s
Major histocompatibility complex; class of proteins determined by polygenic inheritance and multiple alleles; “proteins that are displayed that are genetically coded for”
Where are MHC I’s found
Present on the surface of all nucleated cells
** NOT RBC OR PLATELETS**
Where are MHC II’s located
Present on the surface of some white blood cells, dendritic and macrophage (APC’s)
Explain the macrophage or dendritic cell antigen presentation
Macrophage or dendritic cell will phagocytosis a pathogen, will process it and display the antigen on it’s MHC II
What is the function of a T cell receptor on a helper T cell
Antigen specific (epitope) will bind to displayed epitope on the MHC II of APC
What is the function of a CD4 glycoprotein coreceptor on a helper T cell
Will bind to the MHC II of the APC
What binds to the helper T cell receptor
The MHC II presented antigen epitope on the APC binds to the helper T cell receptor
Simultaneous recognition of self versus nonself is achieved how?
What do these events stimulate?
The MHC II will bind to the CD4 coreceptor on the helper T cell;
These events stimulate the helper T cell to become an activated helper T cell
Activated helper T cells will release ___?
Cytokines; interleukins
What are cytokines
Modulators of the immune response
General function of interleukins
Activate other cytotoxic T cells; activate B cells and antibody production
Activated helper T cell will activate _____
B cells
activated B cells will divide into
Plasma cell and memory cell
What does a plasma cell do
Produce and secrete antibodies in the primary response; first exposure
What do memory cells do
Produce and secrete antibodies in the secondary response/future exposures
What is clonal expansion
Activated B cell will divide by mitosis numerous times
Where are antibodies formed
Made in the spleen and lymph nodes
Describe the primary response
First exposure, short-lived, excrete antibodies in large numbers, about five days or eight cell generations are needed
What is the latent period of the primary response
Lack of antibodies for the antigen, but activities are elevated
What is a titer
Concentration of antibodies
What is the secondary response
Future exposure, anamnestic response
Explain neutralization
Antibodies fill the surface receptors/block the virus, enzyme or toxin to prevent it from attaching normally to its target cell/molecule. Deactivates toxins both endotoxin and exotoxin
What is an antitoxin
Special type of antibody that neutralizes bacterial toxins
Explain precipitation
Antigen is in solution and binds to antibody and forms insoluble complex that precipitates out. Can be filtered
Explain a agglutination
If antigen on surface of bacteria,The antibodies can bind a group together by forming cross linkages, the clump can be filtered out by RES or consumed by phagocyte
Explain opsonization
Antibodies cover bacteria and makes them more readily recognized by phagocytes. Ex: opsons can alter the capsule, protozoan and worms can be found this way when coated with IgE antibodies
Explain the activation of complement
Series of enzymes found in the bloodstream that attack bacterial cells, cause their lysis. Especially true of gram-negative
What are 3 sneaky tricks of pathogens
Antigen switching, cover their antigen up, hide their antigen or make it on accessible
Explain antigen switching
They switch or alter the antigen so the immune system is always behind in the response
Define cell mediated immunity
Antigenic dependent immune response in which cells of the immune system attack infected target cells
Cell mediated immunity cannot be transferred through passive means unless ______
The actual lymphocytes are transferred
Describe the first step of cell mediated immunity
And APC can present the antigen epitope as before in B cell activation
A virgin cytotoxic T cell with a T cell receptor will bind to
Bind to the antigen epitope displayed in the MHC I of the APC and the CD8 coreceptor binding to the MHC I of the APC
The 3rd step of cell mediated immunity involves activated ____ that release ____
Activated helper T cells will release cytokines: interleukins to costimulate the cytotoxic T cell
What happens to the cytotoxic T cell in the fourth step of cell mediated immunity
The cytotoxic T cell becomes activated
And activated cytotoxic T cell will differentiate into ____
Memory T cell, more cytotoxic T cells (“killers”)
Cytotoxic T cell will cause ____ of infected target host cells
Lysis
Cytotoxic T cell will go ____
On surveillance. By touch/kill, it finds an infected host cell and will release perforins and granzymes
What are perforins?
Proteins that punch holes in the membranes of infected target cells
What are granzymes
Proteins that activate enzymes to lead to apoptosis – cell programmed death – suicide
What do cytotoxic T cells specifically target
Viral, bacterial or protozoan infected cells. As well as cancer cells and foreign tissues that have been implanted in the body
What is the function of a regulatory T cell
“Calling off the forces” suppression of response, release cytokines to turn the response off
What are natural killers
Related to T cells, lack specificity for antigens, Must bind to a cell
What do Natural killers kill
Kill without stimulation of specific antigens, destroy malignant in virus-infected cells without previous exposure.
Natural killer cells are always ____
On surveillance for cancer and viral infected cells
What type of T cell is most involved in tissue/organ transplant rejection
Natural killers
How is natural immunity acquired
During normal biological experience
Explain passive natural immunity
Receiving antibodies from mother through colostrum or the placenta
How is artificial immunity acquired
Protection obtained through medical procedures
What is passive artificial immunity
Receiving antibodies produced by another animal. Example: shot for botulism
What is active artificial immunity
Antibodies or lymphocytes produced as a result of immunization. Example vaccinations
When getting vaccinations you cannot receive ____ cells, only ____ responses
Can’t receive killer cells, only humoral responses (antibodies)
What are vaccines – immunizations
The exposure of a person to a material that is antigenic but not pathogenic
Historically vaccines were called what? Exposure was to ____
Variolation. Exposure was to the pathogen directly
Why did people vaccinated with cowpox not get smallpox
The epitopes are similar enough that you recognize them
What does Vacca mean? Who was responsible for the smallpox cowpox study?
Cow. Edward Jenner
What is the purpose of vaccines
To stimulate a primary and secondary anamnestic (memory) response that primes immune system for future exposure of a virulent pathogen
what are the five types of vaccines
Inactivated viruses or killed pathogens, attenuated strains, toxoids, antigenic molecules, genetically engineered
What is in attenuated strain vaccine
Live strains that have lost their ability to be virulent
What are toxoid vaccines
Consist of a purified bacterial exotoxin that has been chemically denatured. Ex: DTP vaccine
What is an anti-genic molecule vaccine
Bits or pieces from pathogens; subunits, capsules, surface proteins
Explain herd immunity
Individuals immune to communicable disease will not harbor it, thus reducing the occurrence of that pathogen. Can provide indirect protection for the non-vaccinated
