1617689
Description
Flashcards by Marjorie P, updated more than 1 year ago
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Created by Marjorie P
over 9 years ago
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| Question | Answer |
| CD4 binds to which domain of which class of MHC on which cell(s)? | This TCR coreceptor binds to MHCII's beta 2 domain on pro APCs |
| CD8 binds to which domain of which class of MHC on which cell(s)? | This TCR coreceptor binds to the alpha 3 domain on MHC1 on target cells |
| Put the following 6 into the correct 3 pairs: CD11aCD18, CD28, CD58, CD2, B7, CD54, ICAM-1, CD80, LFA-2, LFA-3 | CD11aCD18 and CD54(ICAM-1) CD28 and B7 (CD80) CD2 (LFA-2) and CD58 (LFA-3) |
| What are the components of the TCR complex? | TCR, CD3 complex, and zeta proteins |
| What makes up signal 2 and why? | CD28 and B7 make up signal 2 for co-stimulatory signals to activate naive T cells. |
| Which region is the most diverse on the TCR? | CDR3 (complementarity-determining region or hypervariable region) |
| Describe CDRs interaction with the peptide and MHC | CDR1: peptide and MHC CDR2: MHC only CDR3: Antigenic peptide only |
| T/F the TCRs on one cell are clonotypic | True, all the TCRs on the same cell will recognize the same epitope |
| The CDRs are located on the: alpha chain, beta chain, both, neither | the CDRs are located on both the alpha and the beta chains |
| rearrangement of the TCR and BCR gene segments are regulated by which enzyme(s)? | RAG-1, RAG-2, DNA repair enzymes |
| What is SCID? (ex: in Arabian foals) | SCID is a lack of DNA repair enzymes resulting in no functional T or B lymphocytes |
| On the TCR which chain rearranges first? Alpha or Beta? | The beta chain rearranges first on this cell receptor |
| Describe the beta chain gene rearrangement | 1. Dn region binds to Jn 2. Vn binds to Dn Result: V-D-J |
| Describe the alpha chain rearrangement | Vn to Jn (No Dn region!) |
| What 3 things contribute to junctional diversity? | Base Deletions N-region nucleotide addition P-nucleotides |
| What is the most common way to create diversity to the TCR alpha and beta chains? | N-region nucleotide addition is the most common way to create ............... |
| What is N-region nucleotide addition? | This is when up to 10 nucleotides can be added to DNA at the coding regions for the alpha or beta chains (adds diversity) |
| What is TdT? | This enzyme assists in adding nucleotides to DNA at the alpha and beta chain coding regions |
| What are P-nucleotides? | If the V/J and V/D/J coding chains on the DNA are asymmetrical these nucleotides will add in to fill the gaps |
| T/F: TCRs have the ability to edit | False: Only B cells can edit their BCR, and they only have one chance |
| What two things does the TCR require for signal transduction? | CD3 Complex (2x) Zeta proteins (2x) |
| Name the 2 functions of the CD3 complex | 1. Signal Transduction (with Zeta proteins) 2. TCR stabilization on the surface |
| What is the result of a mutation in the CD3 complex? | The TCR cannot be expressed |
| T cells are selected for in the Red Pulp Medulla Bone Marrow Cortex | These cells undergo selection in the cortex |
| What is the approximate ratio of T Helper to T Killer cells? | Helper: Killer 2:1 |
| Do T helper cells help out adaptive immunity, innate immunity, or both? | Both |
| Which cells are responsible for thymocyte selection? | thymic stromal cells (ex: cortical epithelial cells, M0s, and dendritic cells) |
| Do thymic stromal cells possess MCHI, MCHII, both, or none? | Thymic stromal cells have both MCH I and MCH II |
| What cell is the most potent activator of Naive T cells and why? | Dendritic cells because they always express B7 and MHC molecules |
| What causes enhanced expression of B7? | APC stimulated by endotoxin [LPS] interferon-gamma CD40-CD40L binding |
| What does a signal by CD28 cause? | IL-2 production Differentiation of Naive T cell into Effector and Memory |
| In regards to T cells, what is the function of IL-6? | IL-6 promotes IL-2 and IL-2 receptor production and T cell proliferation |
| Which cytokine is the major co-stimulator of Th2 cells? | IL-1 is the major co-stimulator for this kind of cell |
| What are the first 2 steps after and antigen is recognized by a helper T cell? | Antigen recognition induces expression of CD40L on the T cell so it can bind to CD40 on the APC. This CD40-CD40L binding stimulates expression of B7 on the APC. |
| T/F: When T cells proliferate and differentiate, they mostly become antigen-specific memory cells | False: most T cell differentiate into effector cells (small numbers are memory) |
| Where can one find Effector T Helper cells? | Peripheral tissues |
| T/F: Effector T helper cells only need signal 1 for activation | TRUE! they are more sensitive to TCR/CD4 recognition |
| What happens to the effector T cells after an antigen has been eliminated and why is this significant? | There will be a major decline in the effector T cell population which will allow the immune system to return to homeostasis |
| For the most part, where will you find Naive T cells? | Peripheral lymphoid organs |
| Do Naive T Cells have effector functions? | No, they only become activate and differentiate. The Effector T cells actually have effects like cytokine secretion, CD40L presentation, etc |
| Which cells are responsible for the accelerated secondary responses on subsequent exposure to the same antigen? | Memory T helper cells |
| Memory T helper cells differentiate into which types of cells? | More memory and more effector T helper cells |
| How do effector T cells leave the vascular system to enter the infected peripheral tissue? | Since effector T cells down regulate L-selectin and CCR7, while up-regulating CCR10, LFA-1 and VLA-4, this allows LFA-1 to bind to ICAM-1 and VLA-4 to bind to VCAM-1. ICAM-1 and VCAM-1 are found on the peripheral vascular endothelium at the sight of inflammation |
| Where do the Th1 and Th2 subsets develop? | peripheral lymphoid organs |
| What is the function of IL-12 in relation to the T helper subsets? | promotes T-Bet production T-Bet is the Th1 promoting transcription factor |
| What is the function of IL-4 in relation to the T helper subsets? | promotes GATA-3 production GATA-3 is the transcription factor for Th2 |
| What is unique about the IL-12/IL-4 relation? | IL-12 and IL-4 promote their respective transcription factor, while cross regulating the other They keep each other in check basically "Neither can live while the other survives"? Harry Potter anyone? :P |
| What cells can produce IL-12 and why might they do so? | M0s and NKs can produce IL-12 or IFN-gamma in response to pathogens, specifically intracellular bacteria and viruses (Remember IL-12 promotes T-Bet, the Th1 transcription factor) |
| Which IL is produced in response to helminths? What does this cause CD4 cells to do? | IL-4 is produced in response to helminths and causes CD4 cells to differentiate into Th2. |
| Which cytokines does Th1 enhance and suppress? | Enhances: IL-2, IL-12, IFN-gamma Suppresses: IL-4, IL-10 |
| What cytokines does Th2 enhance and suppress? | Enhances: IL-4, IL-5, IL-6, IL-10 Suppresses: IFN-gamma, IL-12 |
| Draw a typical Antibody structure (Seriously, grab a piece of paper and do it labeling all possible parts that you can remember) | |
| Which antibodies do not have a hinge region and why? | Due to an extra constant region, IgM and IgE do not possess this region on the antibody structure |
| Antibodies act in 2 different phases. Which phases? | Recognition phase (BCRs) Effector phase (secreted Abs in humoral immunity) |
| What percentage of plasma proteins is made up by secreted antibodies? | ~20% |
| Alpha, beta, and gamma type globulins have been ID'd due to electrophoretic migration rate. What type of globulin are antibodies? | Antibodies are gamma globulins |
| Which Ig has the shortest percentage of carbohydrate content? | IgG at 3-4% (I know it is a stupidly specific question...but as anything is fair game, had to throw it in...Pg 106, 3rd bullet) |
| If papain is mixed with IgG, what will happen? | Papain cleaves IgG above the hinge region resulting in 2 Fab regions and one Fc region |
| What will happen if IgG is mixed with pepsin? | Pepsin will cut the Ab below the hinge region keeping it intact. The Fc portion will be degraded but the 2 Fab regions are still connected and will be called F(ab')2 |
| What did papain/pepsin experiment tell us about the Fab regions? | If the Ab is cut below or above the hinge region, the Fab can still bind to antigens but will not activate Fc-dependent effector functions |
| What did the papain/pepsin experiment tell us about the Fc region? | If the Fc is still intact (papain) then it can bind to Fc receptors, activate complement, etc |
| T/F: the light chain on an antibody determines the type | False: the heavy chain determines the type of antibody |
| T/F: An Ab has 2 light chains, 2 lambda, 2 kappa, or 1 of each | False: An Ab has either 2 of one, or 2 of the other. It cannot have a mix of both kappa and lambda light chains |
| In humans, which type of light chain is more common? | Kappa -60% Lambda -40% |
| What forms the antigen binding site on the antibody? | the 3 hypervariable regions of the heavy and light chains TOGETHER form the antigen binding site |
| T/F: Each hypervariable region is up to 10 amino acids long | False: Each hypervariable region is only 5-10 amino acids long (I know also a crappy question, but I had to throw it in there) |
| What is another name for the hypervariable regions? | Complimentarity-determining regions (CDRs) because they are complementary to the epitopes on the antigen |
| T/F: Antigen-Ab interaction is irreversible | False: Ag-Ab interaction is non-covalent and reversible |
| Name some noncovalent forces that contribute to Ag-Ab binding | Ionic bonds, van der Waals forces, hydrogen bonds, hydrophobic interactions |
| With regards to Abs, define affinity | This refers to the binding strength between 1 Fab and the epitope |
| With regards to Abs, define avidity. | The total of all the Fab and antigen bindings |
| T/F: IgM has a higher avidity than IgG | True because IgM has more Fab regions that can bind to epitopes |
| When can Abs act as antigens? | Abs can act as antigens if introduced into a foreign host. The host would then begin to make anti-antibodies. |
| Define isotype | The 'class' of Ig which is determined by the variations in the constant regions of the heavy and light chains |
| Define allotype | This refers to the differences in Ig between individuals of the same species *Differences can be used to establish paternity |
| Define idiotypes | This is most specific and refers to the aa combo in the variable regions of each chain. Each idiotype is specific for a particular antigen |
| What is the primary function of an antibody and the possible result(s)? | ***First: bind to the Ag Next it can have a direct effect like neutralization of microbial toxins or...more likely, it will engage other effector molecules like complement proteins or N0s |
| T/F: most effector functions of an Ab are mediated by the Fab region | False: most effector functions of an Ab are mediated by the Fc region of the heavy chain |
| What are Fc receptors? | They are signaling cell surface receptors that bind the Fc portion of an Ab. |
| Which antibodies do not have Fc receptors? | IgM, IgD |
| What is the major Ig in serum? | IgG |
| Where is IgG found? | blood, tissue spaces, extravascular spaces |
| Name the FcgammaR receptors | FcgammaRI FcgammaRII FcgammaRIII (AKA CD64, CD32, CD16) |
| Which Fc gamma receptor is found on B cells? What is it's significance? | Fc gamma RIIB is found on this cell When crosslinked to BCR it inhibits the cell and blocks activation |
| Which Fcgamma receptor has the highest affinity? | FcgammaRI AKA CD64 |
| Which cells have all 3 of the Fcgamma receptors? | Macrophages and Eosinophils |
| Fcgamma receptors on phagocytes interact more or less efficiently with IgG bound to an antigen? Why? | More efficiently because the IgGs basically form a multivalent array and bind with a much higher avidity than free circulating IgG...the IgG surrounding the antigen will trigger engulfment and microbicidal activities |
| Which antibody is most likely to cross the placenta in most species? | IgG |
| How does IgG function as an opsonin? | IgG can assist in agglutination of particulate antigens |
| Neutralizatoin of viruses and microbial toxins form IgG can result in what? | complement activation |
| Which Ig is most efficient in agglutination? | IgM due to its pentamer |
| Which Ig has the highest avidity? | IgM because it has 10 Fab regions |
| Which Ig is the predominant Ig produced by the fetus? | IgM |
| An elevated IgM level in the blood of a newborn is indicative of what? | transplacental infection |
| Where does synthesis of IgA mostly occur? | mucosal lymphoid tissue, especially respiratory and GI tracts |
| Which is the most abundant Ig in the body? | IgA |
| T/F: Secretory IgA is a dimer and serum IgA is generally a monomer | True! Don't forget that the secreted form has a joining chain and secretory component |
| What composes the secretory component of IgA to help transport IgA to the mucosal surface? What other function does the secretory component have? | It is synthesized by epithelial cells and helps protect IgA from proteolytic degradation |
| Which Ig is predominant in various secretions? | IgA |
| How does IgA protect mucosal surfaces? | it prevents attachment of microorganisms and microbial toxins |
| Which Ig(s) participate in agglutination? | IgA, IgG, IgM |
| Which Ig(s) are heat liable at 56 degrees? | IgE, IgD |
| Which Ig is referred to as an reaginic antibody and why? | IgE because it causes histamine release (Hypersensitivity 1) |
| Which three cells has Fcepsilon receptors? | Mast cells, basophils, eosinophils |
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