Specific immune review Flashcards
what is the specificity of the adaptive defence
it recognizes & destroys specific foreign (non-self) substances
explain specific immune memory
initial response to pathogen is slow, but subsequent responses are rapid
what is an antigen
substance that can be recognized by immune system as foreign. These trigger antibody production.
(could be proteins, lipids, polysaccharides on surface or bacteria, fungi, viruses or other non- self things)
causes reactivity & immunogenicity.
what is immunogenicity
stimulates lymphocyte proliferation & antibody production
what is the antigen deteminent (epitope)
Part of antigen that specifically recognize & react w/ antibody
What are the major histocompatibility complex proteins
special proteins on the surface of all body cells, genetically unique to each person. Coded by MHC genome, an inherited combination from mom and dad
- Important in determining tissue compatibility for organ transplant
- *synthesized & exported, they pick u small peptides from the inside of the cell & display them. It shows that it’s health & normal
do all cells have MHC 2 & MHC 1?
all cells express class 1, only some have class 2.
What are peptide fragments
they are what is presented by MHC & allow the immune system to differentiate normal from bad
What are antibodies/immunoglobulins
Gamma globulin proteins in blood that bind to specific antigens to from antigen-antibody complexes
explain the antibody structure
4 Peptide chains (2 light, 2 heavy)
- Each chain has a constant region & a variable region.
- Variable region differes - recognizes & binds to a specific antigen (there are 100’s of different ones)
- Immune system can make an antibody that’ll specifically recognize ANY foreign antigen
What are the 5 major classes of antibodies
1) IgG
2) IgM
3) IgA
4) IgD
5) IgE
Explain IgG antibody class
1) it is the most common one in blood
2) it protects against VIRUSES
3) it activates complement
4) Monomer = small, can cross placenta
Explain IgM antibody class
1) First antibodies to appear following antigen exposure
2) Activates complement
3) Pentamer = large
explain IgA antibody class
1) Found in saliva, sweat, tears, mucus, semen, and breast milk
2) Prevents attachment of viruses/bacteria to epithelial surface
3) dimer = 2
Explain IgD antibody class
1) Found on the surface of B cells
2) it’s a B cell receptor
3) Binding to antigens can activate B cells
4) monomer= small
explain IgE antibody class
1) Attaches to receptors on mast cells/basophils
2) interaction w/ antigen causes histamine release - inflammation/allergic reaction
3) monomer
What do cytotoxic T Cells do
T cells that secrete performs and granzymes to destroy abnormal, virus infected or transplanted cells
what do Helper T cells do
Secrete cytokines that mobilize other immune cells
what do memory cells do
long lived T & B cells that are produced following exposure to an antigen & provide immunity for years
what do APCS do ( antigen presenting cells)
Both specific & non specific
Display non-self antigen on MHC-2 to helper T cells
what do B cells do
antigen presenting cells, differentiate into plasma cells
what do plasma cells do
B lymphocytes that secrete antibodies
what do antibodies do
proteins secreted by plasma cells that circulate in the blood where they recognize & bind to foreign antigens
What are the 5 functions of antibodies
1) Neutralization
2) Opsinization
3) percipitation
4) Agglutination
5) Complement activation
Explain Antibody neutralization
-Antibody binds to antigen. Blocks activity & prevents virus from entering a cell/ prevents a bacteria cell from attaching
explain antibody opsination
antibodies coat foreign cells/molecules & allow macrophages attachment so they can be easily phagocytized
Explain antibody precipitation
soluble antigens (toxins) rendered insoluble when antibodies bind. This causes they to precipitate out of solution.
explain antibody agglutination
clumping cells together due to antigen/antibdoy cross linking
explain antibody complement activation
antigen-antibody complexes activate complement. Which triggers the production of inflammatory chemicals & cell lysis (membrane attack complex)
bigger picture of how an antigen-antibody complex effects immune
1) it inactivates antigens by
-neutralization
-opsinization
-agglutination
-Precipitation
which enhances phagocytosis
2) It activates complement which
-enhances phagocytosis, enhances inflammation
-leads to cell lysis
what are lymphocytes
special defence cells with unique receptors that can recognizant & respond to specific antigens
Main characteristics of B ells
- Mature in bone marrow
- Involved in antibody production
- Humoral immunity (immune response based on antibody production)
- immture B lymphocytes migrate to secondary lymphoid tissue to encounter antigens
- Each cell has a unique B cell receptor
Main characteristics of T cells
- mature in thymus
- Differentiate into several subtypes (Helper-T, Regulatory T, Cytotoxic T)
- cell mediated immunity
What is humeral immunity
B cells & production of antibodies.
Involves CLONAL SELECTION: proliferation by mitosis of those cells that recognize/bind to a specific antigen. Army of clones that target specific antigen
What is a B cell receptor
an IgD antibody expressed to the surface to interact with a specific antigen
B cells can differentiate into..
1) Plasma cells - secrete antibodies (each b cell has a unique antibody on its surface)
2) Memory B cells - long lived cells (provide long term specific immunity to particular antigen)
what do plasma cells do
secrete antibodies
What needs to happen for differentiation to be able to occur
Usually require activation of helper T cells which secrete cytokines
Explain Humoral immunity - Primary response (1st encounter with pathogen in lymphoid tissue)
1) Antigen recognition
- By b cells with a complementary antibody receptor (IgD)
2) Sensitizes B cell
- Costimulation from helper T cell
3) Activates B cell
- Clonal selection: The activated population of B cells divide & produces genetically identical cells
- Somatic Hypermutation: Creates super B cells w/ high antigen affinity
4) Differentiation occurs:
- some become plasma cells
- some become memory b cells
5) The plasma cells secrete lots of low affinity IgM antibodies, specific to antigen
why is somatic hypermutation
activated B cells create super B cells with high antigen affinity
Explain Humoral immunity - Secondary response ( secondary encounter with pathogen)
1) Memory T cells
- rapidly produce hi affinity IgG antibodies
2) Illness is prevented
what is antibody titer
measure of antibody concentration in blood, an indication of immunity
what 2 cells does cell mediated immunity involve
1) Involves T cells
2) Antigen presenting cells
what is T-cell self tolerance
won’t attack own cells
What is positive & negative selection of T cells
- Positive selection: T cell must recognize your MHC proteins
- Negative selection: T cells must not react/attack your self-antigens (MHC)
What are the 3 main types of T cells
1) Helper T cells / CD4+ Cells
2) Cytotoxic T cells / CD8+ cells
3) Regulatory T cells (suppressor cells)
What do helper T cells do
Secrete Cytokines (eg. Interluekins)
what do cytokines from helper T cells do
activate phagocytes
Trigger inflammation
Stimulate division/activate other T & B cells
What do cytotoxic T cells do
Secretion lymphotoxin (eg. Granzymes, perforins)
what lymphotoxin do
Direct killing of virus infected cells, cancer cells, diseased cells by the same mechanisms of NK cells
what do regulatory T cells do
Secrete inhibitory cytokines
what do inhibitory cytokines do
Suppress T & B cell activity
stops lymphocyte activity
What do antigen presenting cells do (eg. Dendritic)
1) Phagocytize/ ingest pathogens
2) Process pathogens & present foreign antigens in MHC II to T cells
3) Activates T cells
why do we need antigen presenting cells
because T cells can only see antigen if its presented in MHC
where does antigen presentation usually occur
in lymphoid tissue
What do virus infected cells do
present foreign antigens - attach MHC protein on cell surface
this will activate T cells
what do sensitized B cells do
Endoytosis of antigen - present foreign antigen attached to MHC protein on cell surface.
This activates T cells
who can activate T cells
1) APC (Dendritic)
2) Virus infected cells
3) Sensitized B cells
What is dendritic cells role
- Professional APCS
- phagocytes
- reside in tissues that are in contact w/ external environment.
- Often the first leukocyte to encounter a pathogen
- constantly sample environment for viruses/ bacteria
- migrate to lymph nodes where they’re presenting antigens to activate specific T & B cells
Explain class 1 MHC
all cells present normal self peptide fragments in MHC 1. If they start presenting abnormal on MHC 1 = kill me.
what would displaying abnormal cell fragments one MHC1 do?
activates cytotoxic T cells to destroy abnormal cells
Explain class 2 MHC
- only APC’s have it
- means “find this & destroy it”
what does class 2 MHC activate
HELPER T cells /CD4+ cells
What do they helper T cells do when they are activated
release cytokines that cause cell division
Explain step by step: Antigen presentation in MHC-1 By virus infected cell
1) Virus infected cell
2) infected cell makes viral proteins
3) Infected cell presents viral proteins/antigens in MHC-1
4) specific cytotoxic T cell secretes chemicals (perforins & granzymes) that destroy infected cell
6) Apoptosis (cell death)
Explain step by step: Antigen presentation in MHC-2 by a phagocyte (Dendritic cell or macrophage)
1) Phagocytosis of pathogen
2) Procession of bacterial antigens in phagolysosome
3) bacterial antigen fragments displayed in MHC-2
4) Specific T helper cell activated by interaction with antigen/MHC2 couples
5) Helper T cell releases Cytokines that attract & activate other leukocytes (B cells)
and the helper T Divdes to produce ore helper T cells and long lived memory helper T cells
Explain step by step: Antigen presentation in MHC-2 by a B cell
1) B cell receptor interacts w/ a specific bacterial or viral antigen - this sensitizes it
2) B cell endocytosis of antigen & presents Antigen in MHC-2
3) Specific helper T cell interacts w/ antigen/MHC complex. This activate the T cell division
4) Helper T cell releases Cytokines that activate B cell. This is called co-stimulation
5) Activated B cells Divide pricing clones, plasma cells & memory B cells
What is active naturally acquired immunity
being infected with a pathogen & forming memory T & B cells & antibodies
what is passive, naturally acquired immunity
Receiving antibodies from mother @ birth via breastmilk, placenta
what is active artificial acquired immunity
vacine -> form memory T & B cells & antibodies
what is passive artificially acquired immunity
gamma globulin injection that just gives u antibodies
What is immunodeficiency
decreased production of normal T & B cells, complement phagocytes or antibodies
ex. Hdgekins lymph node cancer, AIDS (destruction of Helper T
what is autoimmune disease
Failure to distinguish self from non-self
ex. MS (myeline sheath attacked), Hashimoto (thyroid attacked), rheumatoid arthritis (joint) type 1 diabetes (beta cells) lupus (everything)
Immunoglobulines are composed of …
peptide chains
