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Immunology Exam 2
Chapt 10 Activation and Function of T and B cell, Chapt 12 inflammation, tolerance and autoimmunity
62
Immunology
Undergraduate 3
11/04/2012

Additional Immunology Flashcards

 


 

Cards

Term
What type of cells process protein antigens and present linear fragments of the protein to T cells?
Definition
specialized or "professional" APC cells- dendritic cells, macrophages, and B cells
Term
Where are APC's found?
Definition
at the entry sites of the airways, GI tract, and skin; and in lymhpoid organs and tissues throughout the body
Term

 

What type of cells found in the circulation and tissues are the principal APC's for initiating primary T cell repsonses?

Definition

 

Dendritic Cells

Term

 

What are the two types of dendritic cells?

Definition
Plasmacytoid and Myloid
Term

 

What do Plasmacytoid dendritic cells do?

Definition
they make interferons alpha and beta in early immune respnse and are major contributors to the innate phase of the response to pathogens
Term
what do myeloid dendritic cells do?
Definition
they have a major role in the induction of T cell responses
Term
Where can dendritic cells be found?
Definition
they are found in many tissues in addition to the thymus; also found in tissues close to the entry sites for antigens as well as secondary lymphoid organs such as lymph nodes and spleen
Term
Dendritic cells found in tissues are called what and express what?
Definition
they are also called immature dendritic cells and express pattern recognition receptors (PRR) that interact with components of mircoorganisms, particularly viruses and bacteria.
Term
What are toll like receptors? (TLR)
Definition

they are a type of PRR, 

they are a cell surface molecule that interacts with many molecules. ( ex. bacterial DNA, lipoprotien, and lipopolysaccharides, as well as viral RNA and DNA)

Term

 

Gram negative bacteria, which contains lipopolysaccharides interact with what on the dendritic cell surface?

Definition
TLR 4
Term

   Pathogen processing by a dendritic cell induces the expression of ....

Definition
MHC class II and costimulatory molecules 
Term

   Dendritic cells interaction with pathogen results in secretion of many...

Definition

 

cytokines

Term
Of the cytokines secreated by dendritic cells...which is most important?
Definition
IL-12, which has to do with T cell response
Term
The mature dendritic cell reacts with a _____ cell, the dendritic cell presents the ______ and its peptide on the cell wall surface to a _________ with the correct TCR
Definition

The mature DC cell reacts with a CD4+ cell,

presents the MHC class II and its peptide of the cell wall surface to a CD4+ cells with the correc TCR

Term

 

What is the first signal for activating the CD4+ T cell?

Definition
The interaction between peptide/MHC class II on the APC and the V alpha and beta on the T cells TCR is the first signal for activating the CD4+ T cell
Term
What makes the T cell sensitive to a foriegn AG?
Definition
because the TCR can detect as few as four peptides out of thousands expressed on a particular APC
Term
The interaction of _______ regoin of an MHC II, with CD4 enhances the ability of the T cells to respond to AG
Definition

nonpolymorphic region ( the aread outside the peptide binding groove)

*makes a cell 100x more responsive to Ag

Term

______   ______on the surface of dendritic cells, and the CD4+ T cell deliver second signals that enhance and sustain signals delivered by the first signal, the MHC-peptide-TCR interaction. 

Definition

 

Co-stimulatory pairs

Term

 

What is the best known co-stimulatory pair?

Definition
B7 expressed on APC's and CD28 on T cells
Term


Activation of the CD4+ T cell causes it to .....

Definition

reorganize the structure of its internal cytoskeleton and cell membrane 


..and also changes its pattern of gene expression from a resting to an active state

Term
The intial signal of T cell acitvation involves....
Definition
binding of peptide-MHC to the variable alpha and beta regions of the TCR, transmits a signal. (tightly associated with CD3 and the zeta chains)
Term
The formation of the immunologic synapse involves...
Definition
the interaction of APC and peptide with the CD4+ T cells forms an area of contact between the cells (known as the immunlogic synapse). It lasts until the APC and T cell split after 8 hours contact
Term
Toward the end of expansion activated T cells differentiate into....
Definition

effector T cells which can carry out the effector function

( making cytokines, killing cells)

Term
What are the 4 subset of CD4+ T cells based on cytokine production?
Definition
TH1, TH2, TH17, Treg cells
Term
What do TH1 cells do?
Definition
they make IFN-gamma macrophages; IL-2 and TNF-B which activaes CD8+ T cells and NK cells
Term

 

What do TH2 cells do?

Definition

They make IL-4 and IL-13 which influence B-cell class switching to IgE and IgG4 

and IL-5 which activates eosinophils

Term
what does TH17 do?
Definition

make the IL 17 cytokines, of which IL 17 and 22 promote inflammatory responses.

They have been described in RA, MS inflammatory bowel disease and psoriasis

Term
What do Treg cells do?
Definition

 

inhibit the function of the other subsets. They also suppress the activation of the dendritic and B cells. They suppress immune responses directed at self molecules and foreign antigens

Term
Some of the cytokines produced byt CD4+ subsets can be produces by other types of cells such as....
Definition
mast cells and NK cells
Term

 

What is tolerance?

Definition

when the immune system is unresponsive to an antigen

Term

 

What is central tolerance?

Definition

tolerance induced during the early stages of lymphocyte development (immature lymphs encountering AG)

 

occurs in the primary lymphoid organs (bonemarrow/thymus)

Term

 

What is peripheral tolerence?

Definition
tolerance induced in mature lymphocytes
Term
In central tolerance, what happens to T and B cells that recognize self antigens?
Definition
they get deleted
Term
In T cell clonal deletion, immature T cells are eliminated in the thymus by a process called...
Definition
negative selection
Term

 

T cell clonal deletion is most efficient if the mature cell expresses what?

Definition
both CD4 and CD8
Term
Failure to induce complete tolerance may result when,....
Definition
self peptides do not reach the thymus, are hidden, or not presentd on an MHC molecule
Term
What is needed  for tolerence via clonal deletion (Bcells)
Definition
cross linking of surface AB(without T cell help)
Term

 

What is Anergy?

Definition

The functional inactivation of a lymphocyte· 

 a state of Ag-specific non-responsiveness where a T or B cell is present but functionally unable to respond. 

Term
Name some theories of Anergy
Definition

1. B cell receptors are overwhelemd with AGs(prevents cross linking)

2. T cells exposed to high doses of AG by APC (cell loses responsiveness)

3. lack of secondary stimulatory molecule (second signal, prevent T cell activation) 

**B7 on APC CD28 on T CELL***

4.Ag presentation the absence of IL 4,5,6, & 10 (B cell will be anergic [lack immunity to AG])

Term

 

What are the types of immunoregulation?

Definition

·      Ab mediated tolerance:  ·      Ab is passively injected prior to Ag exposure. (maternal anti D problems)

 

   Immune complexes are formed and removed by macrophages preventing activation of the immune system

 

·      Idiotype regulation·      Idiotype regulation: anti-idiotype Ab’s react with variable regions of Ab or T cell receptors so Ag cannot bind or surface Ig cannot cross ling (makes the cell tolerant)


·    Suppressor T cell activity :poorly understood

 
Term

 

What are some factors that affet tolerence?

Definition

1. Dosage and administration

Low doseof AG induces T cell tolerance

high does of AG induces B cel tolerance


2. ·      For tolerance to be sustained when new cells emerge from primary tissue, Ag exposure must be persistent.

   Sub Q favors immunity:   Oral favors tolerance 


3.Fetal-maternal tolerence

·      Cells of the placenta do not express MHC I or II which prevents immune activation


Term

 

What is autoimmune disease?

Definition

¡Immune response generated by the body against its own cells or tissues
¡Key events (tolerance is “broken”)
lRecognition of self antigens by autoreactive lymphocytes
lActivation of these cells to proliferate and differentiate into effector cells
lEffector cells and their products promote tissue injury

Term
Autoimmune disease results when tolerence is broken by what 4 mechanisms?
Definition

1. Genetic mutation

2. loss of tolerance to an organ- specid antigen

3. Ag specific B cell response 

4. persistent organ specific autoimmune disease

Term
What are the general mechanisms of harmful immunity?
Definition

---interactions of AB's with cell surface components

---formation of auto-Ag/autoAb complexes in fluid (and perhaps tissues)

---sensitization of T cells

Term

 

What are the 3 situations in which some autoimmunity is beneficial to the host?

Definition

1. to initiat an immune response to MHC class II molecules and Ags must be presented to activate T helper cells 

2.B cells can recognize the idiotype of AB and produce AB against it. this is anti idiotype AB

3.can regulate the activity of T and B cells

Term

 

What happens to the immune system in Myasthenia Gravis disease?

Definition

the immune system produces ab's that block or destroy many of the muscles' receptor sites for a neurotransmitter called acetylcholine

--with fewer receptor sites avaiable, muscles recieve fewer nerve signals resulting in weakness

(thymus gland may trigger productions of these Ab's thymus is abnormally large in patients)

 

Term

 

What happens during Grave's disease?

Definition

-the body produces an ab to a particular protein on the surface of cells in the thyroid.

the ab associated withi graves disease-thryotropin receptor antibody (TRab)- can mimic the action of the pituitary hormone and override normal regulaion of the thyroid and result in overproduction of thryoid hormones (hyperthyroidism)

Term

 

Thyrotropin receptor antibody (TRab) is involved in Graves disease and also contributes to what?

Definition

o   The same antibody has an “attraction” to tissues surrounding the eyes. It triggers inflammation and other immune system events that result in the signs and symptoms of Grave’s ophthalmopathy. (bulging of the eyeballs) 

Term
What happens in Multiple Sclerosis?
Definition

The immune system attacks the brain and spinal cord

-it demyelinates the protective sheath around white matter neurons and causes lesions on them

(electrical signals are disrupted/halted)

-the brain becomes unable to send and recieve messages--its the breakdown of communtication that causes the symptomes of MS

 

It is a T cell mediated disease

Term

 

What are the signs of MS?

Definition

muscle weakness

decreased coordination

blurred or hazy vision

eye pain

double vision

Term
What happens during Diabetes Mellitus Type 1?
Definition

beta cells that produce insulin are slowly destroyed by the bodys own immune system

·      It is unknown what first starts this, but evidence suggests that both a genetic predispostition and factors, such as a viral infection are involved. 

Term
What are the genetic locations related to type 1 diabetes?
Definition

Genetic locations labeled IDDM1-IDDM18

Term
'What are some conditions that may lead to diabetes mellitus as a secondary condition?
Definition

·      Conditions that damage or destroy the pancreas can induce Type 1

o   Pancreatitis

o   Pancreatic surgery

o   Chemical exposure

 

Term
What happens during rheumatoid Arthritis?
Definition

·      involves abnormal B cell – T cell interaction, with presentation of Ag’s by B cells to T cells eliciting T cell help and consequent production of RF.

·      Certain infections could be triggers for this disease. A theory suggests that an infection triggers an immune response, leaving behind antibodies that should be specific to that organism

·      The antibodies are not sufficiently specific, though and set off an immune attack against part of the host. 

Term
What tests are done to test for MS?
Definition
Rule out MS by blood test for: lyme disease, collagen vaculr disease, and AIDs (they al have similar symptoms)

Visual evoked test (measures electrical signals to the brain)

and spinal tap to indicate MS linked abnormalities suchs as unusual number of WBC or proteins
Term

 

What is Hypersensitivity?

Definition

·      The term hypersensitivity describes the exaggerated responses that cause tissue damage in a host

Term

 

What are the 4 categories hypersensitivity mechanisms are classified into:

Definition

o   Type 1: allergic rxn, (anaphylactic?)

o   Cytotoxic

o   Immune complex disorders

o   Delayed hypersensitivity. 

Term
Type 1 hypersensitivity allergic rxn/anaphylactic is also known as...
Definition
immediate hyersensitivity, this reaction occurs in minutes
Term

 

What is Atopy?

Definition
its a genetic predisposition to Type 1 hypersensitivity and is associated with IgE AB
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