Immune System Flashcards
Characteristics of Innate Immunity
Eliminates all invading agents
Always works the same
Against any type of invading agent.
How fast was innate immunity in responding to a foreign agent?
Works very quickly, recognize foreign agent and try to slow it down/get rid of it while our specific responses take their time to map a better response.
Characteristics of Adaptive Immunity:
Protects against SPECIFIC pathogens.
Depends on activity of lymphocytes
Develops after exposure to environmental hazards.
How fast is adaptive immunity in responding to a foreign agent?
Takes a while- wants to take its time to map the best response possible.
What defenses does innate immunity have?
Physical barriers
Phagocytes
Immune surveillance (destruction of abnormal cells by NK cells in peripheral tissues)
Interferons (coordinate defenses against viral infections)
Steps by which NT cells kill targets:
- Recognition and Adhesion (attach to antigen of abnormal cell)
- Realignment of Golgi apparatus (move towards in front of antigen)
- Secretion of perforin (breaks plasma membrane)
- Lysis of abnormal cell
Interferon Alpha
produced by cells that have been virally affected
Interferon beta
secreted by fibroblasts
slows inflammation in a damaged area
Interferon Gamma
secreted by T cells and NK cells and stimulates macrophage activity.
In an innate defense response, are the cells complete?
NO
What mechanisms can Innate Defenses be activated?
- Complement
- Inflammation
- Fever
Complement:
bind to whatever pathogen we have and stay bound and act as a flag for other immune molecules to come deal with it.
know what it happens to do once it’s activated.
It also lyses cells, and enhances phagocytosis and inflammation.
Inflammation
- Mast cells will release their chemicals and start doing one of many things.
- Increase temp allows for a boost to other immune cells to do better.
Fever
- Pyrogens are crucial
- Some pathogens aren’t able to deal with the increased heat.- Is manageable until a certain point until body tissues don’t work correctly.
Why is it important to have numerous T,B cells?
T, B cells will be specific to one disease, one antigen, otherwise there will be no response. This is why it’s important to have numerous T,B cells.
Lympocyte distribution
- issues maintain different T cell and B cell populations
- Goes around our body
- Use blood vessels or lymphatics for transport
Antigenic determinant
- T and B’s could only recognize one part of the cell- a specific part of the antigen.
Cell-Mediated Immunity:
- Phagocytes activated > T cells activated > direct physical and chemical attack.
Antibody-Mediated Immunity:
- Humoral Immunity
- Activated B cells give rise to cells that produce antibodies
- Acts very indirectly.
If you are a passive response, that means that antibodies are produced:
Naturally: placenta
Artificially: conferred by administration of antibodies to combat infection.
If you are having an active response, that means that antibodies are produced:
- Naturally(someone sneezing on you)/Artificially Acquired active immunity (vaccine)
Specificity
Each T or B cell responds only to a specific antigen (ONLY ONE) and ignores all others
Versatility
-The body produces many types of lymphocytes (need a lot in order to fight off all antigens)
-Each fights a different type of antigen.
-An activated lymphocyte clones itself to fight a specific antigen.
Memory
– Some inactive lymphocytes (memory cells)
* Stay in circulation
* Very fast
* With production of T and B cells comes production of memory cells.
* Provide immunity against new exposure
Tolerance
Immune system ignores “normal” antigens (self- antigens) (OUR ANTIGENS)
- THEY KNOW WHAT OUR OWN ANTIGENS ARE AND DONT ACT UPON THEM- BECOMES AN ISSUE WHEN THEY DO!
T cells:
- Activated when exposed to some kind of antigen
- Comes out of the thymus as naive cells, but still have a lot to learn.
- Need to be exposed to these antigens to make your immune system grow.
- T cells can’t recognize an antigen on their own, so they need antigen-presenting cells (macrophages, phagocytes)
MHC proteins
- Membrane glycoproteins that bind antigens.
- Genetically coded by major hist compatibility complex (MHC) in chromosome 6.
- Protein on the surface of the cell that presents the antigen.
Class 1 MHC:
- Are with all nucleated cells: endogenous antigens (abnormal peptides, viruses), from inside the cell.
Class 2 MHC
- Are on APCs and some lymphocytes: exogenous antigens (from the outside of the cell)
Coming out of the Thymus, T cells could be either
- CD8 or CD4
Haven’t encountered their antigens yet, still in their naive state.
How does a cell become a Tc Cell?
- CD8 > MCH I > Cytotoxic T cell
How does a cell become a Th Cell?
- CD4 > MCH II > Helper T cell
Cytotoxic
- Recognizing something in that cell that is abnormal and kill that cell it’s recognized on.
Helper T cell
- Will start to release cytokines and stimulate other parts of the immune system- helps them become activated and help fight off whatever antigen they find is abnormal.
In recognizing the antigen for Cytotoxic T cells (think steps):
T cell receptor has to recognize Class I MHC and the antigen > It also needs co-stimulation > results in cell division and producing active Tc Cells and Memory Tc Cells.
How will Tc Cells kill cells?
- Perforin- makes a hole in the cell membrane
- Cytokine release- stimulation of apoptosis
- Lymphotoxin release- disruption of cell metabolism
Memory Tc Cells
- Produced with Tc cells
- Stay in circulation
- Immediately form cytotoxic T cells if same antigens appears again.
Regulatory T cells:
- Secrete suppression factors
- Will inhibit lymphocyte response- responses of T and B cells
- Act after initial immune response
- Limit immune reaction to single stimulus.
(IMPORTANT FOR ENSURING THAT WE DONT KILL OTHER CELLS- JUST THE ONE THAT WE WANT)
CD4
- Active helper T cells
- Secretes cytokines
- Important for cell mediated and antibody-mediated immunity responses.
- Bring in macrophages.
- Secretes cytokines
Functions of cytokines:
- Stimulate T cell divisions
- Produce memory T cells
- Accelerate cytotoxic T cell maturation
- Attract and stimulate macrophages
- Attract and stimulate activity of cytotoxic T cells
- Promote activation of B cells
B cells are involved with which immunity?
antibody-mediated immunity (humoral immunity)
B cells attack antigens by
producing specific antibodies
B cells will have what on their surface?
Class II MHC and antibodies
T/F: When an antibody binds to an antigen it activates the B cell by presenting it to the Class II MHC?
FALSEEEE
it becomes sensitized meaning encountered, but not activated.
How does a B cell become activated?
Needs to meet with a Th cell to release cytokines to fully activate the B cell (costimulation)
Steps for B cell to become activated:
Sensitization by binding of antibody to antigen > Activation by Helper T cell to release cytokines to activate B cell
Activated B cells become
plasma cells and have antibody production
Structure of the antibody
tips of the Y structure will bind to the antigens
IgM
First class of antibodies
Class switching- can go from one body to another
Binding effectiveness and immune response is not as good as IgG
Start with IgM and then IgG
Pentameter
IgG
Most diverse and largest group
Will use this antibody the majority of the time
responsible for binding to a multitude of pathogens
pretty small- can cross the placenta
Monomer
IgA
- acterial and viral adhesion (look at B cells and immunity slide and apply an Ig with a response)
- Can provide an adaptive immune response at the physical barrier.
- Circulates around the blood.
- dimer
IgE
- important in allergic responses.
- Can find this in our innate defense mechanism
- monomer
IgD
Found on surface of B lymphocytes membranes and involved in antigen recognition (antigen determinants) Monomer
T/F: Can T cells recognize antigens on their own?
NO! They need the MHC II and I receptors to present the antigen to them
