Term
| What type of cells process protein antigens and present linear fragments of the protein to T cells? |
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Definition
| specialized or "professional" APC cells- dendritic cells, macrophages, and B cells |
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Term
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Definition
| at the entry sites of the airways, GI tract, and skin; and in lymhpoid organs and tissues throughout the body |
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Term
What type of cells found in the circulation and tissues are the principal APC's for initiating primary T cell repsonses? |
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Definition
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Term
What are the two types of dendritic cells? |
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Definition
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Term
What do Plasmacytoid dendritic cells do? |
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Definition
| they make interferons alpha and beta in early immune respnse and are major contributors to the innate phase of the response to pathogens |
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Term
| what do myeloid dendritic cells do? |
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Definition
| they have a major role in the induction of T cell responses |
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Term
| Where can dendritic cells be found? |
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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 |
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Term
| Dendritic cells found in tissues are called what and express what? |
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Definition
| they are also called immature dendritic cells and express pattern recognition receptors (PRR) that interact with components of mircoorganisms, particularly viruses and bacteria. |
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Term
| What are toll like receptors? (TLR) |
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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) |
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Term
Gram negative bacteria, which contains lipopolysaccharides interact with what on the dendritic cell surface? |
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Definition
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Term
Pathogen processing by a dendritic cell induces the expression of ....
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Definition
| MHC class II and costimulatory molecules |
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Term
Dendritic cells interaction with pathogen results in secretion of many...
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Definition
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Term
| Of the cytokines secreated by dendritic cells...which is most important? |
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Definition
| IL-12, which has to do with T cell response |
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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 |
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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 |
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Term
What is the first signal for activating the CD4+ T cell? |
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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 |
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Term
| What makes the T cell sensitive to a foriegn AG? |
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Definition
| because the TCR can detect as few as four peptides out of thousands expressed on a particular APC |
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Term
| The interaction of _______ regoin of an MHC II, with CD4 enhances the ability of the T cells to respond to AG |
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Definition
nonpolymorphic region ( the aread outside the peptide binding groove)
*makes a cell 100x more responsive to Ag |
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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. |
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Definition
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Term
What is the best known co-stimulatory pair? |
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Definition
| B7 expressed on APC's and CD28 on T cells |
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Term
|
Activation of the CD4+ T cell causes it to .....
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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 |
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Term
| The intial signal of T cell acitvation involves.... |
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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) |
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Term
| The formation of the immunologic synapse involves... |
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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 |
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Term
| Toward the end of expansion activated T cells differentiate into.... |
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Definition
effector T cells which can carry out the effector function
( making cytokines, killing cells)
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Term
| What are the 4 subset of CD4+ T cells based on cytokine production? |
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Definition
| TH1, TH2, TH17, Treg cells |
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Term
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Definition
| they make IFN-gamma macrophages; IL-2 and TNF-B which activaes CD8+ T cells and NK cells |
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Term
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Definition
They make IL-4 and IL-13 which influence B-cell class switching to IgE and IgG4
and IL-5 which activates eosinophils |
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Term
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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 |
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Term
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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
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Term
| Some of the cytokines produced byt CD4+ subsets can be produces by other types of cells such as.... |
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Definition
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Term
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Definition
when the immune system is unresponsive to an antigen |
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Term
What is central tolerance? |
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Definition
tolerance induced during the early stages of lymphocyte development (immature lymphs encountering AG)
occurs in the primary lymphoid organs (bonemarrow/thymus) |
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Term
What is peripheral tolerence? |
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Definition
| tolerance induced in mature lymphocytes |
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Term
| In central tolerance, what happens to T and B cells that recognize self antigens? |
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Definition
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Term
| In T cell clonal deletion, immature T cells are eliminated in the thymus by a process called... |
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Definition
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Term
T cell clonal deletion is most efficient if the mature cell expresses what? |
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Definition
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Term
| Failure to induce complete tolerance may result when,.... |
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Definition
| self peptides do not reach the thymus, are hidden, or not presentd on an MHC molecule |
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Term
| What is needed for tolerence via clonal deletion (Bcells) |
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Definition
| cross linking of surface AB(without T cell help) |
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Term
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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.
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Term
| Name some theories of Anergy |
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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]) |
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Term
What are the types of immunoregulation? |
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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
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Term
What are some factors that affet tolerence? |
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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
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Term
What is autoimmune disease? |
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Definition
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¡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
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Term
| Autoimmune disease results when tolerence is broken by what 4 mechanisms? |
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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 |
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Term
| What are the general mechanisms of harmful immunity? |
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Definition
---interactions of AB's with cell surface components
---formation of auto-Ag/autoAb complexes in fluid (and perhaps tissues)
---sensitization of T cells |
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Term
What are the 3 situations in which some autoimmunity is beneficial to the host? |
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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 |
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Term
What happens to the immune system in Myasthenia Gravis disease? |
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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)
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Term
What happens during Grave's disease? |
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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) |
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Term
Thyrotropin receptor antibody (TRab) is involved in Graves disease and also contributes to what? |
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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)
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Term
| What happens in Multiple Sclerosis? |
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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 |
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Term
What are the signs of MS? |
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Definition
muscle weakness
decreased coordination
blurred or hazy vision
eye pain
double vision |
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Term
| What happens during Diabetes Mellitus Type 1? |
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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.
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Term
| What are the genetic locations related to type 1 diabetes? |
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Definition
Genetic locations labeled IDDM1-IDDM18 |
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Term
| 'What are some conditions that may lead to diabetes mellitus as a secondary condition? |
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Definition
· Conditions that damage or destroy the pancreas can induce Type 1
o Pancreatitis
o Pancreatic surgery
o Chemical exposure
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Term
| What happens during rheumatoid Arthritis? |
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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.
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Term
| What tests are done to test for MS? |
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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 |
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Term
What is Hypersensitivity? |
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Definition
· The term hypersensitivity describes the exaggerated responses that cause tissue damage in a host
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Term
What are the 4 categories hypersensitivity mechanisms are classified into: |
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Definition
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o Type 1: allergic rxn, (anaphylactic?)
o Cytotoxic
o Immune complex disorders
o Delayed hypersensitivity.
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Term
| Type 1 hypersensitivity allergic rxn/anaphylactic is also known as... |
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Definition
| immediate hyersensitivity, this reaction occurs in minutes |
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Term
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Definition
| its a genetic predisposition to Type 1 hypersensitivity and is associated with IgE AB |
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