Chapter 17: Types of Immunity and Immunology Flashcards
Immunity
The ability of an organism to recognize and defend itself against an infectious agent
Susceptibility
The opposite of immunity. Being vulnerable to harm by infectious agent
Immunology
The study of adaptive immunity and how the immune system responds to the specific infectious agents and toxins
Adaptive/Acquired immunity
The ability of a host to mount a defense against a particular infectious agent by physiological responses specific to that infectious agent, not hereditary immunity
Naturally Acquired immunity
(1) Most often obtained by having a specific disease (2) Immune system responds to molecules called antigens and invading infectious agents (3) Activates T cells and produces molecules called antibodies
Example of Naturally acquired
Antibodies transferred from mother to fetus through placenta
Artificially acquired Immunity
Obtained by receiving an antigen by the injection of vaccine or immune serum that produces immunity
Active immunity
Created when the persons own immune system activates T cells or produces antibodies or other defenses against an infectious agent (antibodies can last a lifetime or just a few weeks/months)
Active Natural Immunity
Exposure to infectious agent; is produced when a person is exposed to an infectious agent
Active Artificial Immunity
Immunization; produced when a person is exposed to a vaccine containing, live, weakened or dead organisms or their toxins. Body’s immune system remembers the antigen to which it has responded from
Passive immunity
Created when ready-made antibodies are introduced into the body, passive because the host does not have to make antibodies
Passive Natural Immunity
Maternal antibodies; is produced when antibodies made b other hosts are introduced into a new host
Passive Artificial Immunity
Antibodies from other sources are injected (Being injected with antivenin injection after being bitten by poisonous snake)
Antigen
A substance the body identifies as foreign and toward which it mounts an immune response to or an “immunogen”
What are antigens made of?
(1) Large complex protein molecules (2) Some are polysaccharides, some are glycoproteins and some are nucleoproteins
Why are proteins used to make antigens?
Proteins have a greater antigenic strength because they are more complex
Epitopes or antigenic determinants
Area on the molecule to which antibodies can bind
Polyclonal antibodies
Different antibodies that all recognize different epitopes on a specific microorganism
What determines the chemical structure of a cells antigen?
Genetic info
Do microorganisms have one or more antigens on their surface?
Can have multiple on their surface
Importance in making a vaccine
Determining how the body is going to react to different antigenic determinants
Hapten
Small molecule that can act as an antigen if it binds to a larger protein molecule, can act as epitopes on surface of proteins
Antibody
(1) A protein produced in response to an antigen that is capable of binding specifically to the foreign antigen (2) Each antigen binds to a specific antigenic determinant and may inactivate an antigen
Titers
(1) The quantity of a substance present in a specific volume of body fluid (2) Increases during infection (3) Serves as an indication of an immune response by the body
Antibody titer
Quantity of antibody needed to bind to and neutralize a particular quantity of an antigen
Where do lymphocytes develop from?
Stem cells
Where are lymphocytes processed and matures in? What do they mature into?
Lymphoblasts are processed and matured in tissue and become lymphocytes both B and T, then the B matures in bone marrow, T matures in the Thymus and then they both go to the lymph once they are done
Where does B cell differentiation take place?
In the bone marrow
Where are B cells found?
Lymph Tissue and GALT (Lymphoid digestive tract), Peyers patches
What type of acquired immunity are B cells found in?
Humoral immunity
What do B cells secrete?
Antibodies that react with particular antigens
Where do T lymphocytes undergo differentiation?
Thymus
Where are T cells found
Same places as B cells, Thymus, Lymph tissue and GALT
What type of acquired immunity are T cells found in?
Cell mediated immunity
What are the 4 types of cells that T cells produce? And what do they do?
(1) Cytotoxic T cells: directly interact with bad cells (2) Delayed hypersensitivity T cells: help macrophages and stimulate the macrophage to destroy pathogen (3) Helper T cells: Help B cells make antibodies (4) Regulatory T cells: Regulate immune system
After differentiation where do T cells go?
Migrate along lymph tissue and blood
Natural Killer cells (NK)
Nonspecifically kill cancer cells and cells infected with viruses without utilizing specific immune responses
What do NK cells release and do?
(1) They release various cytotoxic molecules that perforate membranes leading to lysis (2) Other molecules enter through pores and fragments its DNA causing apoptosis (3) NK cells are then infected by interferons
Apoptosis
Programmed cell death
What are the 2 types of immunity lymphocytes give rise to?
Humoral immunity and Cell-mediated immunity
Humoral immunity
Is carries out by antibodies circulating in blood
What is the process of Humoral immunity?
(1) When stimulated by antigen, B cells initiate a process that leads to release of antibodies (2) Done before cells enter a cell
Cell mediated Immunity
Carried out by T cells within a cell (involve differentiation and activation of several kinds of T cells and the secretion of cytokines, NO B cells)
What is the process of Cell mediated immunity?
(1) Processed antigens on MHCII molecule bind to T receptor (2) IL-1 secreted from macrophages and IL-2 secreted from T cells activate T cells which differentiate into TH1 and TH2 (3) TH1 releases interferon, a cytokine that causes infected amcrophages to become resensitized to cytokines (4) Most effective in clearing the body of virus infected cells but also participates in defending against fungi and helminths, cancer and foreign tissue
Properties of Immune Response
(1) Recognition of Self vs Non-self (2) Specificity (3) Heterogeneity (4) Memory
Clonal selection hypothesis
(1) Explains that embryos containing many different lymphocytes, each genetically programmed to recognize a particular antigen, make antibodies to destroy it (2) Next, if lymphocyte recognizes that antigen after development is complete it divides to produce clones and then a group of identical progeny (3) However, if during development the lymphocyte encounters its programmed antigen (meaning its targeting itself) the lymphocyte is destroyed (When b cell recognizes specific epitope on antigen, it binds to antigen, engulfs, presents fragment as MHCII to TH2 cells and divides then B cells differentiate into memory or plasma cells)
Tolerance regarding clonal deletion theory
(1) Immune system destroys the lymphocyte that targets self before they can make more copies once development is over (2) Can be acquired through organ transplants with the help of an immunosuppressant
Cross reactions regarding immunity
Reactions of a particular antibody with very similar antigens, resulting in either an antigen for multiple strains of a similar infection of antibodies made that destroy both host cells and antigen cells (can be good or bad)
Importance of heterogeneity in immune response
(1) Ability to make a variety of different antigens if a bacterium or foreign agent has more than one kind of antigenic determinant (2) Producing different antibodies for different kinds of epitopes
Importance of Memory in immune response
Stand ready for years or decades to quickly initiate antibody production
Anamnestic response
Secondary quick response due to the ability to recall seeing the antigen before
Where do B cells carry their antibody?
On its membrane so it can bind immediately
What does binding of an antigen do?
It sensitizes or activates B cells causing it to divide
Plasma cells
Large lymphocytes that synthesize and release many antibodies like those on their membrane
Presenting the antigen
After B cells have antigens bound to their antibody it takes both into the cell where it processes the antigen and breaks it down into small fragments so that they can bind to MCHII
Major Histocompatibility complex
MHCII is a molecule on surface of B cells where small fragments of antigens bind to, it presents the antigen so T cells can come and help
How do T cells work with MHCII?
T cells recognize the antigen plus MHCII and become activated to produce interleukin 2 which helps B cells expand and multiply to become plasma cells
Between direct contact of which 2 cells do B cells form
Direct contact between B cells and T cells lead to B cells to proliferate and make B memory cells
Properties of Antibodies (immunoglobins)
(1) Y shaped protein molecules composed of 4 polypeptide chains (2) 2 identical “L light chains” (3) 2 “H heavy chains” (4) Y shaped part of antibody is called a monomer
What are the chains of the immunoglobin binded by?
Bind by Disulfide bonds
What two regions are there on the immunoglobin and which is which?
(1) Constant regions: determine class that immunoglobin belongs to, 3/4 of the antibody and is considered the “business end” (2) Variable regions: Have a particular shape and charge that enable the molecule to bind a particular antigen, 2 prong part of Y can identify the epitope, 1/4 of antibody, Light chain
Binding sites on Y protein are identical to what?
(1) Parent B cell; first B cell gets inserted into their membrane to form receptor (2) Fc fragments determine roles of each antibody (3) Fab fragments is responsible for the specificity of the antibody (light chain)
Involvement of introns and exons in Antibodies
(1) We have 5 classes of constant regions (2) Antibody regions are from spliced DNA fragments put together which is why we can make many types of antibodies (3) Coding regions spliced together make the constant “heavy region: and the variable “light chain”
IgG
(1) Main class of antibodies found in the blood (2) Produced in the largest quantity and small in size (3) Only immunoglobin that can cross the placenta and provide antibody protection (4) Found in milk and colostrum (5) Transports across the placenta, serum and extravascular (6) 1 unit
IgA
(1) In Blood, Tears, Saliva, Mucous membranes (2) Secreted into blood (3) Stays in secretions (4) Guards entrances of the body (5) Can have 1 or 2 units [binds 2-4 antigens] (6) In colostrum (7) Coats bacteria and viruses preventing them from adhering to mucosal surfaces
IgE
(1) Also called regain (2) Special affinity for receptors on the plasma membranes of basophils (3) Plays a damaging roles in the development of allergies (4) In body fluids and skin (5) 1 unit (6) In lymph
IgM
(1) Receptor on B cell that recognizes epitope (2) Found as a monomer on b cell and is secreted as a pentamer by plasma cells (3) First antibody secretes into blood during primary response (4) Causes organisms to clump because it activated complement (5) Antibody of the inherited ABO types (6) High levels of IgM means recent infection or exposure to antigen (7) “J” chain (8) Can bind to 10 antigens
IgD
(1) Found on B cell membranes and is rarely secreted (2) 1 unit
Which cells have MHCII?
B cells, T cells, Macrophages, Dendritic cells
Primary response takes place where?
Lymph nodes
T independent antigens
(1) B cells activated by binding antigen result in proliferating and forming plasma cells (2) No class switch (3) Blood cells are T independent (4) End product is IgM antibody’s and no B memory
T dependent antigens
(1) Need T cells (2) majority of our immune responses (3) B cells become an antigen presenting cell and make contact with T helper cells to activate (4) T cells provide chemicals for a class switch (5) T cells secrete lymphokines that cause b cells to produce B memory cells and plasma cells, leading to production of IgG antibodies
What makes B cells
T cells secrete lymphokines and other factors that cause B cells to produce B memory cells
When does primary response occur?
When the antigen is first recognized by the B cell
What happens after antigen is recognized by B cell during Primary response?
(1) B cells divide to form plasma cells which increase synthesize antibodies (2) The in a few days antibodies appear in blood plasma and increase concentration
What are the first antibodies during primary response
IgM which bind to foreign substances directly
Cytokines
(1) Small signaling proteins that trigger proliferating B cells to switch from making plasma cells that make IgM to plasma cells that make IgG (2) Chemical mediator
Class switch
Is the change in production of antibody type, from IgM to IgG
Secondary response
When antigen recognized by a memory cell enters the blood
Anamnestic response
Seeing infectious agent a second time
Memory cells during secondary response
(1) Make response fast and are present in greater numbers (2) Have the ability to divide rapidly into plasma cells and other memory cells
Production of IgM vs IgG during secondary response
IgM is only released for a short amount of time and then IgG is produced in greater quantities for a longer duration
Primary response vs Secondary response regarding Antibody and Lag period
(1) Primary: Long lag period, IgM is present longer, IgG then begins to be produced (2) Secondary: Barely any lag period, IgM is present for a short time and little amount, IgG is present earlier on and is present for a while, more antibodies present overall
Antigen-Antibody reactions of humoral immunity is best against what?
Best against bacterial infections and neutralizing toxins and viruses that have yet to invade cells
What happens to antigens that reach lymph tissue without being recognized by antigens?
Macrophages grab and present to B cells
What is the first step of getting rid of an antigen
(1) Forming an antibody-antigen complex
Inactivation of an antigen can happen in which 3 ways?
(1) Agglutination/Immune complex (2) Opsonization (3) Immune complexes
Agglutination
(1) sticking together of microbes (2) IgM produces strong agglutination whereas IgG produces weak agglutination (3) Can be seen with naked eye
Complement
(1) IgG and IgM take part (2) IgM can sometimes lyse cells (3) Viruses with envelope are lysed through complement
Neutralization
(1) Inactivates toxins that are very small and secretes it from the cell (2) Stops toxins from entering a cell (3) IgM, IgA, IgG are all effective neutralizers
Opsonization
(1) Antibodies ability to point out to macrophage that there is an antigen (2) Usually involves capsulated antigen
Monoclonal Antibodies
Are antibodies produced in a laboratory by a clone of culture cells that make one specific antibody
Method learned in class of making monoclonal antibodies
Mixing myeloma cells [because they divide rapidly]
(malignant cells of the immune system) with sensitized lymphocytes [used because they will make the particular antibody]
Hybridomas
When two cells mix together containing genetic info from each original cell, divide indefinitely and produce antibodies
How is the antibody a hybridoma produces determined?
It is determined by the antigen to which the lymphocytes were sensitized to before their progeny were mixed with myeloma cells
Therapeutic monoclonal antibodies
Target only malignant cells without harming host cells
Process of Cell mediation
(1a) Immature T cell recognizes antigen sitting on MHCII complex and becomes TH since it has MHCII protein and is activate (1b) If MHC1 then Immature T cells to activation of cytotoxic T cells instead of T helper (2) TH with Interleukin 2 then becomes either memory T cells, TH2 cells or TH1 cells
Cell mediated immunity is against what? and what cells are involved?
Against intracellular bacteria, macrophages and TH1 [delayed sensitivity cells]
Humoral immunity is against what? and what cells are involved?
Against foreign antigens, TH2 cells connects with B cells that become activated
Cell mediated immunity
(1) No B cells (2) Direct action of T cells (3) Clears body of viruses and other pathogens that already invaded host cells (3) Involves T cells
T cells involvement in cell mediated immunity
(1) They do not make antibodies (2) T cells do not have a cell membrane receptor protein (3) Cannot be activated directly by antigen (4) antigen presentation on the surface of cell and MHC must be present
Nucleated cells have which kind of MHC?
MHC1
Antigen presenting cells have which type of MHC?
MHCII
Cell mediated responses usually begin with what?
Processing of antigen
How are cytotoxic T cells activated?
Activated by antigen presented by MHCI
What are leukotrienes or cytokines?
Chemical substances released by T cells that trigger certain immunological reactions
What do IL-1, IL-2 and gamme interferons do?
cause undifferentiated cells from getting out of hand
TD cells (delayed sensitivity cells
(1) Release various lymphokines including (a) macrophages chemotactic factor (b) macrophage activating factor (c) migrating inhibiting factor (d) macrophage
TC cells (cytotoxic killer cells)
kill infected host cells with NK cells
AIDS targets what cell?
T cells
How do killer cells kill?
(1) TC cells and NK cells destroy target cells by releasing perforin (2) Usually kill cells without MHC complexes
Cytotoxic cells act on what cells?
Virally infected cells
NK cells at on mainly which kinds of cells?
Tumor cells, cells of transplanted tissue, cells infected with intracellular agents
How do NK cells bind?
They bind directly onto malignant cells or other target cells
NK cells contain which protein to help kill cells?
Perforin which is released when binding to a target cell
NK cells purpose
To kill cells before they have the opportunity to further infect
What does Lymphokine macrophage activating factor do?
Released by TD cells to combat infections of bacteria that continue to grow into macrophages. Macrophages then increase production of toxic hydrogen peroxide and other enzymes to speed up inflammatory response
Super antigens
are a class of antigens that cause non-specific activation of T-cells resulting in polyclonal T cell activation and massive cytokine release
Autoimmunity
When host tissues are attacked
Antigens that bind with different specificities
Polyclonal
Memory cells remain where until ready to respond?
Lymphoid tissue
What do granulomas do?
Granulomas wall of pathogens that macrophages fail to kill
Toxoids
Inactivated toxins
Vaccines
Live, attenuated organisms, dead organisms, part of organisms or a toxoid
Subunit vaccines
produce fewer side effects than hole cell killed vaccines and offer greater safety than attenuated vaccines
TH1 cells are also known as what kind of cells?
Delayed hypersensitivity cells, helps macrophages by releasing cytokines or interleukin to stimulate macrophages
How do T helper cells help macrophages
T helper releases chemical factors to speed up the reaction of macrophage destruction
What do cytotoxic T cells do?
Release perforin that cause cell to explode and die then it releases pathogen fragments and antibodies can be made from that
Where is IgE attached to on mast cells and basophils?
Attached to the mast cell on their constant region, antigen binds to hyper-variable region
One enough allergen is bound to IgE cells, what happens?
IgE cells cluster together on the mast cells/basophils forming degranulation (releasing factors)
Agglutination is due to what?
Due to recognition of an antigen as part of a cell, usually whole cells are involved (Viruses, Blood typing)
Precipitation is due to what?
Due to free floating antigens, only the antigen carbohydrate is present rather than a whole cell
Expectations from body when a familiar viral infection enters your body
IgA expected to be in the mucus (stimulate adaptive immunity)
How viruses and cancers persist in the body
Virus enters B cells and B cell keeps making antibodies with virus, Burkitts lymphoma
