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78 Cards in this Set
- Front
- Back
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When do B cells become activated?
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When their receptors are crossed linked by antigens
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B cell co-receptor
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works with B cell receptor in binding to antigens and helps activate B cells
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Where does the stimulatory molecule B7 bind to?
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The CD28 receptor of a T cell
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T1-1 vs. T1-2
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T1-1 = single antigen at a time
T1-2 = multivalent antigen |
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Thymus independent antigens
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Capable of directly activating a B cell without a helper T Cell
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Examples of TI-1 antigens
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LPS or Bacteria DNA
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Why are babies unresponsive to TI-2 antigens?
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B cells in babies are immature and undergo apoptosis due to the binding with a multivalent antigen (such as TI-2 antigens)
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Where is IgA mostly secreted?
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In the mucosal tissues
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How do the four classes of IgG differ?
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They have different hinge structures
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Waldeyer's Ring
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ring of tissues in the mouth containing the tonsils and adenoids located around the entrance to the gut and airway
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M cells
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specialized cells that transport microorganisms to gut-associated lymphoid tissue
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B cell co receptor
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Consists of 3 proteins: CD21, CD19, CD81
Simultaneous ligation of B cell receptor and co-receptor increases signal 1000-10000 fold |
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How do toll-like receptors play a role in thymus independent antigens?
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TLRs in combinations with B cell receptors and co-receptors can initiate the B cell to differentiate without the help of a T cell
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Example of TI-1 antigen
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LPS
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Example of TI-2 antigen
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cell wall of S. pneumoniae
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TI-2 antigen
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These antigens only stimulate B cells that are specific to the antigen. The are believed to cross-link B cell receptors and co receptors extensively so there is no need for additional signals such as TLRs.
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Why is a co-receptor important?
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Delivers an additional and necessary signal to the B cell to being differentiation
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What does the co receptor CR2 bind to?
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The C3d
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mitogen
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chemical substance that encourages cell division or mitosis
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Where does the co-stimulatory molecule B7 bind to?
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CD28 of a naive T cell
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Why are babies unresponsive to TI-2 antigens?
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All of their B cells are immature and immature B cells that bind with multivalent antigens (such as TI-2) go through apoptosis
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Bcl-xl
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prevents cells from going through apoptosis
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Intrinsic v. Inducible properties of resting B cells
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Intrinsic:
1. Have surface Ig 2. Surface MHC class II Inducible: 1. growth 2. somatic hypermutation isotype switching |
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Intrinsic vs. Inducible properties of plasma cells
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Intrinsic:
High Ig secretion No inducibility possible |
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neutralizing antibody
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binds to antigen and prevents disease
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non-neutralizing antibody
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does not prevent disease
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How do toxins work?
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They bind to a receptor on cell surface and are endocytized which they are released from the receptor and wreak havoc.
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4 ways which make antibodies flexible
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1. rotate Fab arm
2. waving the Fab arm 3. wag the Fc tail 4. bending of Fab "elbow" |
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How much mucus can one produce in a day?
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1 L
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How much mucus can one produce per day while sick?
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2-4 L
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Where are IgA2 most concentrated?
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In the colon
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5 ways a virus can evade the immune system
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1. inhibition of adhesion molecules which prevent adhesion of lymphocytes to infected cells
2. inhibition of MHC class I upregulation by IFN-gamma and impairs recognition of APC by CD4 T cells 3. inhibition of peptide transport by TAP so the antigen is not presented properly or at all 4. encodes complement control protein to inhibit complement activation of infected cell 5. encodes Fc receptor that blocks effector functions of antibodies bound to infected cells |
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superantigen
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these antigens bind to sites shared by many T cells and the consequence can be massive production of cytokines and systemic shock
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ADA deficiency
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ADA is involved with purine degradation and lack of ADA causes buildup of nucleotide metabolites which can be toxic to developing T cells
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Problems with bone marrow transplants
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The donor must share HLA alleles
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What T cell quota causes AIDS
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<200 T cells/ml
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Type I hypersensitivity
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This immune reaction involves IgE which activates mast cells
Example: hayfever |
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Type II hypersensitivity
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cause by small molecules that bond covalently to cell surface components which can be perceived as foreign material
Example: penicillin |
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Type III hypersensitivity
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small soluble immune complexes formed by soluble protein antigens binding to the IgG
These complexes can bind to walls of small blood vessels or alveoli of the lungs |
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Type IV hypersensitivity
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caused by products of antigen-specific effector T cells which can stimulate cytotoxic T cell responses
Example: responses to bug bites or venom |
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Why are people allergic to penicillin?
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The penicillin binds to RBC and some individuals are capable of producing antibodies against which results in lysis of the RBC
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How do blood types work?
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Blood typing works by assigning a type to an individual who may make an antibody against another blood type
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Why is type O the universal donor?
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Because the recipients do not make antibodies to type O because O has no antigen markers (i.e. A or B)
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Who is the universal recipient? Why?
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AB because these individuals do not make antibodies to any receptor because they carry them themselves
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TB skin test
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test injects M. tuberculosis protein antigens intradermally or intracutaneously to test for whether an individual has been exposed or has received the vaccine
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chemokines secreted by Th1 cells
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macrophage recruitment to site of antigen
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IFN-gamma secreted by Th1 cells
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activates macrophages increasing release of inflammatory factors
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TNF-alpha & LT secreted by Th1 cells
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local tissue destruction and increased expression of adhesion molecules in local blood vessels
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IL-3/GM-CSF secreted by Th1 cells
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stimulate the production of macrophages
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What effects to mast cells have on the GI tract?
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increased fluid secretion (diarrhea & vomiting)
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What effects to mast cells have on the airway?
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decreased diameter and increased mucus secretion (phlegm & coughing)
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What effects to mast cells have on the blood vessels?
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Increased blood flow & permeability (inflammation, increased lymph flow)
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Why do allergic responses exist?
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To fight parasites
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Which hypersensitivity is cell mediated?
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Type IV
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Which immunoglobulin is responsible for activation of complement?
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IgM
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Where is IgA2 most concentrated?
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It the gut tissue
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Mechanisms that contribute to immunological self-tolerance
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1. negative selection in the bone marrow and thymus
2. Expression of tissue-specific proteins in the thymus 3. No lymphocyte access to some tissues 4. Suppression of autoimmune responses by regulatory T cells 5. Induction of anergy in autoreactive B and T cells |
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Graves disease
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individuals produce antibodies that bind to TSH receptor. This causes overproduction of thyroid hormones
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systemic lupus erythematosus
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autoimmunity directed at self antigens present in almost every cell of the body
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rheumatoid arthritis
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individuals have stimulated B cells that make IgM, IgG, and IgA antibodies specific for the Fc region of IgG
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Privileged sites
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The immune system does not see antigens from these sites
Example: eyes |
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molecular mimicry
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where antigens are similar to self peptides and the individual produce antibodies against the antigen and also reacts with self
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Types of vaccines
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killed/inactivated viruses
live-attenuated viruses subunit viruses |
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killed/inactivated virus vaccines
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these viruses have been treated so that they can no longer replicate but still resemble the same structure
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live-attenuated virus vaccines
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these viruses have been conditioned to not grow well in humans and thus do not cause little or no disease
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subunit virus vaccine
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the antigenic component of a virus
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ISCOMs
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lipid coating around an antigen that can be injected and fuse with the cell membrane
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chronic vs temporary Hepatitis C infection
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30% of individuals will eliminate the virus but 70% will have chronic infection causing liver damage
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National Vaccine Injury Compensation Program
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Compensates individuals who get sick from a childhood disease that they were vaccinated for
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mixed lymphocyte reaction
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recipient blood cells are mixed with killed donor cells to see if the donor T cells proliferate
The more the proliferation, the more mismatched the HLA are |
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indirect allorecognition
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Molecules that are derived from dead donor cells are presented by recipient dendritic cells. The body then makes alloantibodies against the donor
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direct allorecognition
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Recipient T cells recognize donor dendritic cells
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corticosteroids
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anti-inflammatory properties, used as immunosuppressive drugs
they work by fusing into the cell and binding to intracellular receptors and changes gene expression |
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Why do retinal transplants not need to be HLA matched?
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The eyes are privileged site and so the immune system does not see the eye antigens
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As the grade of GVHD increases, what are the consequences?
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1. Increased erythroderma
2. Increased serum bilirubin 3. Increaed diarrhea |
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Graft Versus Host Disease
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Where donor T cells attack recipient tissue
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p53
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tumor suppressor gene
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Characteristics of tumor cells
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1. stimulate own growth
2. ignore growth inhibiting signals 3. immortal 4. avoid death from apoptosis 5. develop own blood supply 6. leave site to invade others 7. replicate continuously 8. evade/outrun immune system |
