Innate to Adaptive Immunity Flashcards
What cell produces defensin and cathelicidin?
Epithelial and white cells
By what mechanism do defensin and cathelicidin neutralize bacteria?
They are positively charged so they bind to negatively-charged pathogen membranes, into which they insert themselves to form lethal pores.
True or false: Most of the bacterial organisms are beneficial.
True
What is the function of innate immune system?
To detect intruders that have ventured too deep into the body’s structures, and then arrange for their inactivation, destruction, and removal.
Name three structures that are recognized by the innate immune system.
- PAMPs- Foreign molecular structures called pathogen-associated molecular patterns
- DAMPs- Stress or damage indicator molecules expressed by body cells, called damage-associated molecular patterns
- The absence of certain normal cell surface molecules, which would certainly indicated a problem- this recognition is done by NK cells
What is PRR?
Pattern-recognition receptors.
Where are PRRs found?
One the surface or on the inner membranes of MOST CELLS IN THE BODY
What are “Toll-like receptors”?
They are a type of PRR that recognizes a foreign molecular structure humans DO NOT have.
What cells are Toll-like receptors found?
Most cells of the body
A pathogen binds to a TLR found on a endothelial blood vessel cell.. What happens next?
Signaling cascades are activated within the cell that lead to the expression of cytokines and chemokines that cause or increase inflammation.
What is it called when there is an increase in blood vessel diameter, stickiness, and leakiness with an efflux of fluid and phagocytic white blood cells into the tissues?
Inflammation.
Identify the final transcription factor that is most commonly activated in inflammation.
All TLR except TLR3 use the IRAK pathway. The net effect is to activate the mother of all inflammatory transcription factors, NF-kappa B
Can TLRs bind DAMPs?
Yeah. Took me a long time to get this but Yea!
What is one disadvantage and one advantage of innate immunity?
Advantage- Fast
Disadvantage- cannot adapt to totally new challenges- it only sees a few established patterns
What cell is responsible for the connection between the innate and the adaptive immune response?
Dendritic cells
What and where are dendritic cells activated?
Dendritic cells are activated at the wound site by cytokines and chemokines released by local cells
Are dendritic cells marcophages?
Yes
So a dendritic cell is activated, now what?
Dendritic cells are activated by chemokines and cytokines. Then they begin phagocytizing any and everything including foreign molecules derived from the invaders. It then travels to the nearest draining lymph node to show what it has eaten to the lymphocytes
What is the role of lymphocytes?
Recognition of foreignness
What is the role of phagocytes?
Eating and Digestion
True or False:Lymphocytes have a hundred thousand cell surface receptors that are all different so each cell can recognize a hundred thousand different antigens.
False. A lymphocyte may have a hundred thousand receptors on its surface, but all are identical; so each cell can recognize only one foreign shape
Define: Antigenic determinant or epitope
Only a small part of a large antigenic molecule. perhaps 10-20 amino acids that fits into the lymphocyte’s receptor
Does lymphocyte diversity exist before or after the antigen comes in?
Before
Generally what happens after the lymphocyte binds its antigen?
The naive lymphocyte is activated and begins to proliferate so that a clone of identical cells is produced. Some of its cells differentiate and begin to secrete proteins which get the immune response rolling.
What is immunologic memory?
Occurs when lymphocytes are long lived, so that the factory remains expanded and the next time we encounter that organism we can usually overwhelm the invader before it can establish an infection. Accomplished through memory cells
What is the role of B cells?
They protect the extracellular spaces of the body with by releasing antibodies into the fluids.
What is the role of T cells?
They themseles survey the surfaces of the body’s cells, looking for ones that have ingested antigens, have parasites within them, or are dangerously changed or mutated
What short-range mediators do activated T-cells release after restimulated by local antigen-presenting cells?
Lymphokines
What is the role of lymphokines?
Induce a much-augmented inflammatory response by attracting and activating monocytes and macrophages
Where are T cell develope?
Where do they mature?
Bone Marrow
Thymus
What are the two main classes of T cells?
Helpers and Killers
What are the five specialized subtypes of T helper cells?
- Th1
- Th17
- Th2
- Tfh
- Treg
What is the role of Type 1 Helper T cells or Th1 cells?
Recognize antigens and produce lymphokines to attract macrophages.
What is the role of Type 17 Helper T cells or Th17 cells?
Causes focused inflammation that is more powerful than Th1. There are some implications in many serious forms of autoimmunity
What is the role of Type 2 Helper T cells or Th2 cells?
They stimulate macrophages to become ‘alternatively activated’ then function in walling-off pathogens and promoting healing, a process that usually takes place after the pathogen-killing Th1 response. IMPORTANT in parasite immunity
What is the role of Follicular Helper T cells or Tfh cells?
After stimulation by antigen, migrate from I cell areas of lymph nodes into the B cell follicles, where they help B cells get activated to make the IgM, IgG, IgE and IgA antibody subclasses
What is the role of Regulatory T cells or Treg cells?
Make lymphokines that suppress the activation and function of their sibling T helper cells.
What is the role of cytotoxic or killer T cells, CTL?
Destroy any body cell they identify as bearing a foreign or abnormal antigen on its surface
What is the role of CD4 and CD8?
They are surface molecular markers that increase the affinity for an antigen and help activate them
What cells contain CD4 on their surface?
Th1, Th2, Th17, Tfh, Treg
What cell(s) contain CD8 on the surface?
Killer T cells, CTL
On what cell is MHC Class II found?
Dendritic Cells
What Helper T cells are designed to recognize antigens that are loaded onto what antigen-presenting molecule?
MHC Class II
On what cell(s) are MHC Class I molecules found?
ALL CELLS
What occurs when a CTL binds a cell with displaying the appropriate antigen?
It delivers a ‘lethal hit’ signaling the target cell to commit suicide by activating an internal self-destruction process (apoptosis)
Do B cells require the simultaneous recognition of an associated MHC molecule?
No
What is the name of a fully differentiated B cell?
Plasma cell- a protein production factory (antibodies)
What are the five classes of antibodies?
- IgG
- IgM
- IgD
- IgA
.5. IgE
Describe IgG
Most abundant antibody in the blood. There are two adjacent IgG molecules that bind antigen
Can IgG activate complement?
Yes
What antibody is critical in protecting the newborn until it can get its own antibodies?
IgG. It is able to protect the fetus because it is able to pass the placenta
What is the first antibody to appear in the blood after an exposure to a new antigen?
IgM
What antibody is better at activating complement than IgG?
IgM
What is the role of IgD?
This antibody is inserted into B cell membranes as their antigen receptor
Where is IgA primarily found?
In the secretions like saliva, tears, genitourinary and intestinal fluids, and milk
What is the role of the secretory component and what antibody is it associated with?
The secretory component is acquired from epithelial cells during the process of being secreted. It allows IgA (the antibody it is associated with) to be resistant to digestive enzyme
What antibody is associated with mast cells?
IgE
What happens to a mast cell when IgE is bound by an antigen?
It will cause the mast cell to make prostaglandins, leukotrienes and cytokines and release its granules which contain powerful inducers of inflammation like histamine
What is the true role of IgE?
Resistance to parasites, such as worms.
Describe Type I Immunopathology.
Immediate hypersensitivity. Too much IgE to an environmental antigen. Can cause allergies (partly genetic) and anaphylactic shock
What occurs during anaphylactic shock?
mast cells throughout the body are suddenly degranulated and release their histamine
Describe Type II Immunopathology.
Autoimmunity due to antibodies that react with self. Stick and destroy cells as innocent bystanders
Describe Type III Immunopathology.
An antibody is made to a soluble antigen. Antigen-antibody complex is too small to be eaten by macrophages and is trapped in the basement membrane of capillaries. There it activates complement and destroys adjacent tissue.
What are the general symptoms of type III immunopathology?
arthritis, glomerulonephritis, pleurisy, and rash
What drugs commonly can cause Type III Immunopathology?
Penecillin at large doses
Foreign serum (antiserum for rattlesnake venom) this is called serum sickness
Patients with systemic lupus erythmatosus, SLE, make antibodies to their own DNA. What immunopathology would this fall under?
Immunopathology III because some soluble DNA can always be found when the antibody reacts to that it is too small and will get trapped in basement membranes causing inflammation in different tissues
Describe Type IV Immunopathology.
T cell mediated. Can be either autoimmue or more commonly innocent bystander injury
Give two examples of Type IV immunopathology
Tuberculosis- most of the cavity formation in lungs is T cell-mediated not bacterium-mediated
Acute viral hepatitis- most of the liver destruction is by killer T cells
What is Chronic frustrated immune responses?
Antigen is not “self” but is something you can’t get rid of: like you won gut bacteria (inflammatory bowl disease) or (celiac disease)
What cells does the AIDS virus infect?
Th cells
What protein allows AIDS to gain access to Th Cells?
Envelope glycoprotein, gp 120, binds to the CD4 molecules on their surface
What enzyme allows AIDS to incorporate its genome into the DNA of the host cell?
Reverse transcriptase- copies RNA into DNA and inserts into the cells DNA becomes latent and then becomes activated with the cells becomes activated.
