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Questions and Answers
What role do CD4 proteins play in immune response?
What percentage of peripheral lymphocytes do mast cells constitute?
What is the primary function of CD8 proteins?
What surface molecule confers NK cells the ability to lyse IgG coated targets?
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Which type of cell is responsible for producing antibodies within the immune system?
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Which cells do not express TCR or immunoglobulins (Igs)?
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How are lymphocytes expressed in response to antigens?
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What type of cells can NK cells kill without prior exposure to microbes or tumors?
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What is a characteristic of integrins in T-cell function?
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Which of the following is NOT a component of the complement system?
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What percentage of circulating lymphocytes typically express the CD8 protein?
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What is the composition of lymphocytes specific for any single antigen before exposure?
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Which receptor recognizes self MHC I molecules to inhibit NK cell activity?
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What cytokine do NK cells release to activate macrophages?
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What do the majority of CD4-expressing cells function as?
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Which pathways are involved in the activation of plasma proteins in the complement system?
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What distinguishes polyclonal lymphocyte proliferations from monoclonal lymphoid tumors?
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Which cell type is primarily responsible for initiating T-cell responses against protein antigens?
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What role do naive T cells play in the immune response?
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Where are follicular dendritic cells primarily located?
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What type of molecules do dendritic cells express to facilitate antigen presentation?
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What allows lymphocytes to migrate effectively during immune responses?
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Which function is associated with plasma cells in the lymphoid organs?
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What is the primary function of receptors expressed by dendritic cells, such as TLRs and Lectins?
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Which cytokines are involved in stimulating the proliferation of NK cells?
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Which function is NOT performed by T-lymphocytes in innate immunity?
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What is the role of danger signals in the context of innate immunity?
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Which of the following is true about the innate immunity system?
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Which T-lymphocyte type is primarily responsible for killing infected cells?
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What activates the killing and secretion of IFN-γ by NK cells?
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Which T-lymphocyte subtype inhibits immune responses to prevent reactions against self antigens?
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What type of immunity does not exhibit specificity for antigens?
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What is the primary role of MHC molecules in the adaptive immune response?
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Which cells are responsible for presenting antigens to T cells?
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Which class of MHC molecules is expressed on all nucleated cells?
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What characteristic of MHC genes accounts for the variability among individuals?
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Which is a function of macrophages in the adaptive immune response?
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What do the a1 and a2 domains of Class I MHC molecules form?
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What is a consequence of MHC's role in transplantation?
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Where are peptides derived from proteins presented by Class I MHC molecules primarily generated?
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Which type of immunity do macrophages participate in for the elimination of intracellular microbes?
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Which organs are known as primary lymphoid organs?
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Study Notes
Mast Cells
- Comprise approximately 5-10% of peripheral lymphocytes.
- Capable of producing inflammatory mediators.
- Do not express T-cell receptors (TCR) or immunoglobulins (Igs).
NK Cells (Natural Killer Cells)
- Larger cells containing abundant azurophilic granules.
- Can kill virus-infected and tumor cells without prior exposure.
- Identified by surface molecules, including CD16 (Fc receptor for IgG) which facilitates antibody-dependent cell-mediated cytotoxicity (ADCC).
- Activity regulated by a balance of activating and inhibiting receptor signals.
- Inhibitory receptors recognize self MHC I molecules, maintaining self-tolerance.
Plasma Proteins and Innate Immunity
- Plasma proteins like complement system components are activated by microbes.
- Activation pathways: alternative, lectin, and classical pathways.
- Mannose-binding lectin and C-reactive protein also play roles in innate immunity.
- Lung surfactants enhance phagocytosis of microbes.
Cytokines Influencing NK Cells
- Key cytokines include IL-2 and IL-15 for proliferation, IL-12 for activation and IFN-γ secretion.
T-Lymphocytes Overview
- Comprise three major populations:
- Helper T-lymphocytes: Activate B cells and other leukocytes.
- Cytotoxic T-lymphocytes: Kill infected cells.
- Regulatory T-lymphocytes: Limit immune responses and prevent autoimmunity.
T-Lymphocyte Activation
- Develop in the thymus from hematopoietic stem cells.
- Contain CD4 (60% of T-cells) that binds to MHC II and assists other immune cells.
- Contain CD8 (30% of T-cells) that binds to MHC I to kill infected cells.
- Integrins and CD28 play roles in adhesion and activation.
B-Lymphocytes
- Only cells capable of producing antibodies, mediators of humoral immunity.
- Mature in the bone marrow, constituting 10-20% of circulating lymphocytes.
- Unique DNA rearrangements allow differentiation between polyclonal and monoclonal lymphocyte proliferations.
Dendritic Cells
- Key antigen-presenting cells for T-cell activation.
- Found in epithelia and interstitium, capturing antigens.
- Express many receptors for antigen uptake and present antigens with MHC molecules.
Lymphocyte Recirculation
- Lymphocytes continuously move between tissues and lymphoid organs.
- Naive T cells must circulate to encounter antigens, while activated T-cells migrate to infection sites.
- Plasma cells remain in lymphoid organs, producing antibodies.
Major Histocompatibility Complex (MHC)
- MHC molecules display peptide fragments for T-cell recognition, essential for adaptive immunity.
- Class I MHC expressed on all nucleated cells and platelets, crucial for recognizing intracellular antigens by CD8+ T cells.
Macrophages
- Part of the mononuclear phagocyte system, crucial in the adaptive immune response.
- Process and present antigens to T-cells, playing a key role in both cell-mediated and humoral immunity.
- Act as effector cells in the elimination of intracellular pathogens.
Immune System Tissues
- Divided into primary (central) lymphoid organs for lymphocyte maturation and secondary (peripheral) lymphoid organs for immune response initiation.
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Description
This quiz explores various cell types involved in the immune response, focusing on mast cells, NK cells, and other peripheral lymphocytes. It covers their characteristics, functions, and contributions to inflammation and defense against infections. Test your knowledge on the fundamentals of immunology and cellular functions.