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23 Cards in this Set
- Front
- Back
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1. Which cells are antigen-presenting?
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B, macrophage, dendrites
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Which cells have "Class I" MHC?
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Most nucleated cells - "target cells"
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What is the role of he T-cell receptor?
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TCR binds to antigen, CD4 binds to MCH2
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Describe how Th1 cells are able to interact with and activate macrophages
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Phagocytosis of foreign body --> oxidative burst using superoxide anionPresentation of parts on MHC2 receptors on cell surfaceTh-CD4 proteins recognize antigenTh cell releases interleukin (IL2) = act B, NKT, Th, Tc cellsand interferon gamma (IFgamma) = act macrophageBinds to macrophage receptor signaling an increase in enzyme building for pathogen destruction
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Describe how NK cells are able to recognize and destroy infected cells and cancer cells lacking MHC-I molecules
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Recognize: no MHCI receptors = cancerous or viral down regultionDual receptor systemBinds to common glycoproteinBut, does not have MHC1 = fails to bind it = release of toxins by NK = perforiins and granzymesIf both MHC1 and CGP were present, would not kill cell
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State how NKT cells can activate macrophages and NK cells
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Recognize antigen via CD1d and once activated, can act as Th cell releasing IFN-gamma to activate macrophages and NK cells
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what's the name of the receptor that NK cells have that is a second method of activation besides IFN-gamma via Th cells?
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CD1d
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What are Neutrophils and their function?
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Phagocytic, release toxic chemicals in "cytotoxic burst" that kill friendly as well as enemy cells.
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Describe Phagocytosis mechanism
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Bacteria are engulfed by a macrophage and placed in a phagosome
A lysosome fuses with the phagosome forming a phagolysosome An activated Th1 lymphocyte binds to a peptide/MHC-II complex on a macrophage by way of its TCR and CD4 molecule Co-stimulatory molecules such as CD40L on the Th1 cell then bind to CD40 on a macrophage The Th1 lymphocyte secretes the cytokine interferon-gamma (IFN-gamma) that binds to IFN-gamma receptors receptors on the macrophage The IFN-gamma activates the macrophage enabling it to produce more hydrolytic lysosomal enzymes, nitric oxide, and toxic oxygen radicals that destroy the microorganisms within the phagosomes and phagolysosomes |
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What is the function of MHC complex and where are they expressed?
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Presentation of antigen fragments, self-recognition = min autoimmune
MHCI = most nucleated cells, MHC2 = macrophage AND B-cell (anything that's a sentinal) |
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Describe the different types of T cells and their function
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Helper T cells (TH cells)
Once activated, they divide rapidly and secrete small proteins called cytokines that regulate or "help" the immune response Cytotoxic T cells (Tc cells) Destroy virally infected cells and tumor cells, and are also implicated in transplant rejection Memory T cells Antigen-specific T cells that persist long-term after an infection has resolved TCM and TEM (central/effector memory) May be either CD4 or CD8!!Regulatory T cells (Treg cells) Suppressor T cells crucial for the maintenance of immunological toleranceto shut down T cell mediated immunity towards the end of an immune reaction and to suppress auto-reactive T cells that escaped the process of negative selection in the thymus Natural Killer T cells (NKT cells) Special kind of lymphocyte that bridges the adaptive immune system with the innate immune system. Unlike conventional T cells that recognize peptide antigen presented by major histocompatability complex (MHC) molecules, NKT cells recognize glycolipid antigen presented by a molecule called CD1d Once activated, these cells can perform functions ascribed to both Th and Tc cells (i.e. cytokine production and release of cytolytic/cell killing molecules) |
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Describe T cell activation and maturation
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Activated by antigen presenting "sentinel cells" such as phagocytes and B-cells
Maturation – helps to develop cells that are correctly functioning “self” cells 1. T-progenitor cells enter cortex (dbl neg) 2. As TCR alpha is being made the T cell begins undergoing positive and negative selection 3. Positive Selection- In thymus, permits survival of only those T cells whose TCRs recognize self-MHC molecules (self-MHC restriction) 4. Negative Selection- eliminates T cells that react too strongly with self-MHC or with self-MHC plus self-peptides.cortex |
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Describe the different B cells
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Plasma B cells
Large B cells exposed to antigen secreting antibodies “antibody factories” An electron micrograph of these cells reveals large amounts of rough endoplasmic reticulum, responsible for synthesizing the antibody, in the cell's cytoplasm Memory B cells types of B cells and their function Formed from activated B cells that are specific to the antigen encountered during the primary immune response These cells are able to live for a long time, and can respond quickly following a second exposure to the same antigen |
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Describe B cell activation
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Activation
T-cell dependent first signal comes from antigen cross linking the B cell receptor (BCR) Second signal comes from co-stimulation provided by a T cell. B cell processes and presents the same antigen to the primed Th cell, the T cell secretes cytokines that activate the B cell. These cytokines trigger B cell proliferation and differentiation into plasma cells. Isotype switching to IgG, IgA, and IgE and memory cell generation occur in response to T-dependent antigens T-cell independent Many antigens are T-independent, meaning they can deliver both of the signals to the B cell Mice without a thymus (nude or athymic mice that do not produce any T cells) can respond to T-independent antigens Many bacteria have repeating carbohydrate epitopes that stimulate B cells, through so called pattern recognition receptors, to respond with IgM synthesis in the absence of T cell help |
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Describe B cell maturation
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Mature in Red bone marrow
Lymphocyte -> pro B cell -> pre B cell -> coexpression of IgM, IgD -> mature B cell Antibodies B cell development occurs through several stages, each stage representing a change in the genome content at the antibody loci An antibody is composed of two light (L) and two heavy (H) chains, and the genes specifying them are found in the 'H' chain locus and the 'L' chain locus In the H chain loci there are three regions, V, D and J, which recombine randomly, in a process called VDJ recombination, to produce a unique variable domain in the immunoglobulin of each individual B cell Indep act B cells = IgM Th dep B cells = IgE, IgG, IgA |
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What is the complement cascade and its role in immune response
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complement is not a cell but a group of proteins
these proteins circulate in the blood help to recruit phagocytes to site of inflammation and activate them bind to receptors on phagocytes, helping to remove agent of infection form pores in the invader or infected cell’s membrane (like the NKs do) activate mast cells to release histamine and other factors complement plays a role in inflammatory responses of both the innate and adaptive immune responses |
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Since the goal of the complement system is the production of C3/5 convetase, what do these enzymes do?
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Classical Pathway goal is to activate C3 convertase -> C3a/b mediating inflam/membr attack complex
Alternate pathway same goal; but initial activation of the cascade is direct activation of C3b and other prots by endotoxins, polysaccharids or cell wall components to form convertase C3 convertase binds to properdine -> C5 convertase -> C5a/b mediating inflam/membr attack complex C3A/5A = inflammatin C3B = opsonization C5B = membrane attack complex Receptors for C3a and C5a are present on the surface of endothelial cells, mast cells, and phagocytes -> inflammatory response -> releases histamine -> vasodilation/vasoconstriction |
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The significance of the major histocompatibility complex (MHC) in the immune response:
a Serves to minimize autoimmunity or “self reactivity” of the immune system b Serves to present fragments of antigens to T cells c Used by helper T cells to regulate the expansion of antibody producing B cells d All of the above |
all of the above
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What cells get activated FIRST in a immune response (the body is seeing the antigen for the FIRST time)?
a. T cells b. B cells |
T cells, usually
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Q6. What cells are involved in a immune response, when the body is seeing the same antigen for the SECOND time?
a. T cells b. B cells |
B cells
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Q7. ____________ are responsible for the production of antibody against free pathogens and soluble products from pathogens while ____________ destroy pathogen and virally infected cells and abnormal cells.
a. Cytotoxic T cells, B cells b. Macrophages, T cells c. B cells, helper T cells d. B cells, cytotoxic T cells |
B cells and Tc cells
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Diff betw NK cell and NKT cell?
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NK kill direclty, NKT facilitate the process like a normal T-lymphocyte
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Tlymph maturation
Single thymocyte has both CD4/8 = double positive selection - bind = ____ Negative selection - bind = ____ Naïve - 2% remaining - into circulation |
live, die
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