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59 Cards in this Set
- Front
- Back
- 3rd side (hint)
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What is the essential linker between the adaptive and innate immunity?
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Cytokines!
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What does lysozyme do?
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Breaks the cell walls of bacteria. Found in human saliva, tears, and sweat.
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What is opsonization
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augmented phagocytic activity
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What is the first cell to arrive at the site of infection?
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PMN -- polymorphonucleated neutrophils. These are the major phagocytic cells that migrate into tissues. They secrete cytokines that draw other cells to sites of infection (diapedesis). They are granulocytes.
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What are acute phase proteins?
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Proteins found in the serum that bind to microbes and augment phagocytosis. Example is CRP.
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Which molecule of the complement cascade works in inflammation to recruit cells to sites of injury?
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C5a
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What is the NK cell function in the immune system?
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NK cells are generally like the T cells of innate immunity. They can kill cells directly if they find they have lost their MHC I molecule (viral infection), or they can activate macrophages via IFN-g secretion.
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Which part of the thymus contains dividing thymocytes?
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The cortex
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Which organ is the major site of production of antibodies?
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Spleen
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Where is T lymphoctye regulation fine tuned?
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In the gut
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What happens to T helper cells that are activated in the paracortex?
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Some will stay and help B cells begin to differentiate, some will exit via the efferent vessels and enter the blood.
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Who presents to the T cells in the lymph node?
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Dendritic cells
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Antigens in the blood will activate B and T cells where?
Antigens in the tissues will activate T and B cells where? |
In the spleen.
In the lymph nodes. |
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The #1 APC is . . .
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macrophages
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Will low molecular weight agents cause an immunse response?
Will complex proteins? |
no. agents must be high molecular weight.
yes. complex proteins make the best Ag. |
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Do sugars, i.e. the LPS of a gram-neg cell, make good Ag?
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No, proteins are best Ag.
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What are haptens?
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A molecule that is not immunogenic itself, but becomes immunogenic when conjugated to a carrier prot. Can then stimulate a response by itself.
i.e. penicillin conjugated to self protein - sensitivity reaction |
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What is the charateristic feature of TI antigens?
What Ab is produced? |
They have repeating chemical units, i.e. the flagellin tail of bacteria.
IgM |
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Why are superantigens bad?
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They activate many T cells, causing major cytokine production and TSS.
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What is a Xenograft? Allograft?
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Graft from different species.
Graft from same species. |
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How does an adjuvant help an immune response?
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They evoke stronger B and T cell responses by slowing their passage in the blood, promoting inflammation, attracting macs and lymphoctyes to tissue site. Human adjuvants include aluminum.
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Which portion of the BCR does complement bind to?
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The constant region (Ch2)
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What amino acids make up the the hinge region of the antibody?
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Cystein -- disulfide bridges
Proline -- flexibility |
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Antibody classes are defined by the amino acid differences in which region?
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The constant region of the heavy chains.
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Which part of the Ab binds to PMNs, macs, NKs and other cells?
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The Fc portion binds to the Fc receptors on these cells.
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What do the terms isotypic, allotypic, and Idiotypic refer to?
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Iso: heavy chain differences
Allo: small allelic differences on constant regions bet 2 people Idio: HVR differences |
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What is another name for the HVR regions?
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complementarity-determining regions
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What are anti-Ids?
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Antibodies produced to our own Abs, they recognize the CDR regions as foreign.
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Does Ab digestion with papain yield a product capable of precipitating Ab?
Does pepsin? |
No, papain chews it into 2 useless arms.
Yes. the constant heavy chains are cut but the paratope remains intact. |
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What is the most common of the gammopathies?
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Multiple myeloma. Secretions of monoclonal Ab in urine.
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What is the only transplacental isotype?
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IgG (but not IgG2)
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An NK cell bound to an Fc region of an Ab is known as what?
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An ADCC: antibody dependent cell-mediated cytoctoxic cell.
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Which Ab are capable of activating complement?
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IgG and IgM. Definitely IgM.
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What is the difference in function of the monomeric and dimeric forms of IgA?
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IgA1 is found in the blood, IgA2, is found in the mucosal epithelial in contact with the external environment. Neither activate complement.
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Does IgA specialize in bacteria or viruses?
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Viruses
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Elevated levels of IgM in the fetus indicated what?
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Congenital or perinatal infections.
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Which Ab is susceptible to proteolytic degradation?
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IgD
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Which Ab is present in lowest serum concentration? Highest?
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IgE, IgG
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What does a high level of IgM in the blood indicate?
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A current or recent infection
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When is a B cell antigenically determined?
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When the cell has successfully rearranged 1 heavy chain locus and 1 light chain locus, each of a defined specificity. Can still undergo isotype switching.
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What precedes the V and J regions in the light chain?
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The leader sequence
What is it's function? Is it also in the heavy chain? |
The leader sequence helps pulls the translated protein product into the ER, where it is cleaved off.
yes in heavy chain |
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What is order of rearrangement of the variable regions of the heavy chain?
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DJ first, then VDJ
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Are the extra J segments still present in the primary transcript?
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Yes.
When are they removed? What else is removed in this process? |
During processing, the introns and also IgM or IgD chain.
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Explain the process of deleting DNA between variable regions (V region).
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Uses an RSS sequence. Complementarity allows H-bonding.
Rag prots stabilize the bonds. V(D)J recombinase cleaves. |
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What happens to B cells that do not form productive rearrangements?
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Apoptosis
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What is allelic exclusion/
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Only 1 of the possible alleles for the heavy and light chains are used in the final product. Keep each B cell specific for 1 antigen.
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Rag proteins are only expressed in 2 types of cells at 2 specific stages of development. Name them.
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pre-B and pre T
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Gene rearrangement, combinatorial joining, and segment diversity account for which type of variability (specifically)?
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CDR3
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After VDJ recombinase cleaves its target, what event occurs that creates more variability in the Ab?
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p and t nucleotides are added via TdT.
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Somatic Hypermutation accounts for which kind of diversity?
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CDR1 and CDR2
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What initiates somatic hypermut?
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Antigen exposure!
Where does it occur? |
In the germinal center
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Explain the role of AID in somatic hypermutation.
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AID deaminates cystidine in ssDNA and then replaces it with Uracil. Other repair enzymes then find the "mistake" and replace it with any of the 4 bases.
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What are S sequences? Where are then in the DNA?
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Switch region genes, flank (5') the constant region sequences.
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Explain the role of AID in class switching.
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AID again deaminates the cystidine to uracil. UNG removes the uracil portion of the base, leaving an abasic nucleotide. Other proteins then nick out the rest the abasic nt. If this happens on both sides of the DNA, two ends of teh DNA can find each other and DNA can be looped out.
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What effect does IFN-g have on the B cell?
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Will induce B cell isotype switching.
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Where does splicing occur in the cell?
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Within the nucleus
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How does the cell decide to make secreted or membrane-bound Ab?
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If the poly A site for one or the other is read. Secreted comes first, then membrane-bound.
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Which 2 constant region lack a switch region?
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IgM and IgD
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WHy is rearrangement significant in aiding expression of the BCR? WHy don't other cells rearrange their BCR genes?
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Because rearrangment brings the promoters and enhancers in close enough proximity that they can help each other out. Increased txn results.
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